[PATCH 00 of 67] Transparent Hugepage Support #18

[PATCH 00 of 67] Transparent Hugepage Support #18

[Andrea Arcangeli]

Hello,

I merged memory compaction v7 from Mel, plus his latest incremental updates
into my tree.

Large order allocations without __GFP_WAIT were grinding the system to an
unusable state if run frequently and the VM was invoked frequently, but I
deferred looking into the VM until I combined it with memory compaction.
Memory compaction didn't solve the problem in fact (that would have been too
easy), so this time I tracked it down to lumpy reclaim which I nuked and now
direct reclaim with memory compaction in the page faults works fine and system
remains responsive and doesn't start swapping despite tons of cache freeable.

You can trace the memory compaction working with your workload with something
like this:

stap -ve 'probe kernel.function("try_to_compact_pages") { printf("x") } probe kernel.function("try_to_free_pages") { printf("y") }'
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5: run completed in 0usr/30sys/29754real ms.

I also merged set_recommended_min_free_kbytes in kernel so nobody risks to
forget to run hugeadm. It won't be run if you boot with
transparent_hugepage=0. But it will be run later if you enable transparent
hugepage with "echo always >/sys/kernel/mm/transparent_hugepage/enabled".
(however running it later if there's already unmovable stuff fragmenting the
memory will be too late)

If there's any sluglishness and (I don't see it anymore after nuking lumpy
reclaim) you should try this:

	echo never >/sys/kernel/mm/transparent_hugepage/defrag

That way only khugepaged runs memory compaction (see
/sys/kernel/mm/transparent_hugepage/khugepaged/defrag).

Full list of changes:

1) set HUGETLB_PAGE when TRANSPARENT_HUGEPAGE is set
2) select COMPACTION when TRANSPARENT_HUGEPAGE is set
3) have TRANSPARENT_HUGEPAGE depend on MMU
4) fix a bug in migrate that didn't split the hugepages when invoked by kernel
   (through compaction for example) instead of moves_pages syscall
5) Add set_recommended_min_free_kbytes in kernel
6) Add GFP_IO_FS back to GFP_TRANSHUGE so when defrag sysfs control is enabled 
   compaction runs (removing it was a minor attempt to decrease the
   unusability created by lumpy reclaim, they never intended to be not set)
7) set defrag to always by default (previous default setting was "never")
8) Fix oops in memcg when migration is invoked on a signalled task
9) Fix lockdep error in memory compaction when trying to drain lru lists
   (migrate_prep is not mandatory so I commented it out for now)
10) removed lumpy reclaim
11) memory compaction
12) fix to memory compaction to remove an unnecessary optimization reading the
    page_order if page_buddy is set but outside of zone->lock which is
    racy and crashes.

It's not as well tested as #17 but after the last couple of fixes everything
seems fine.

This is the tree I recommend to use for benchmarking (note: I recommend to try
both with "echo never >/sys/kernel/mm/transparent_hugepage/defrag" and the
default "echo always >/sys/kernel/mm/transparent_hugepage/defrag"). The only
other tuning I suggest is to decrease the khugepaged/scan_sleep_millisecs.

To take full advantage of it in all apps, we also need to sort out how to make
glibc extend vma->vm_end of anonymous vmas in 2M aligned chunks to see the
exact speedup gcc gets from transparent hugepages on host without
virtualization on certain files that requires >200M of ram to build. A kernel
workaround is possible too but personally I like the current simpler kernel
code and to address it in userland which should be more efficient and much
simpler, but we'll see...

quilt:

	http://www.kernel.org/pub/linux/kernel/people/andrea/patches/v2.6/2.6.34-rc3/transparent_hugepage-18/
	http://www.kernel.org/pub/linux/kernel/people/andrea/patches/v2.6/2.6.34-rc3/transparent_hugepage-18.gz

git: (note after the clone you've to run
"git fetch; git checkout origin/master" because it'll be rebased, and you
should check that "git diff a56565c0eb27da00bfdd46f54ad738cabdc05996" shows zero
difference to be sure)

	git clone git://git.kernel.org/pub/scm/linux/kernel/git/andrea/aa.git

(apparently right now I still get a slightly older tree for both quilt and git
that I've overwritten in quilt case and that I changed origin/master branch on
git, I assume it takes a bit to be available on git.kernel.org, which is why I
specified to check with git diff a56565c0eb27da00bfdd46f54ad738cabdc05996)

Thanks,
Andrea

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[PATCH 01 of 67] define MADV_HUGEPAGE

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Define MADV_HUGEPAGE.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---

diff --git a/arch/alpha/include/asm/mman.h b/arch/alpha/include/asm/mman.h
--- a/arch/alpha/include/asm/mman.h
+++ b/arch/alpha/include/asm/mman.h
@@ -53,6 +53,8 @@
 #define MADV_MERGEABLE   12		/* KSM may merge identical pages */
 #define MADV_UNMERGEABLE 13		/* KSM may not merge identical pages */
 
+#define MADV_HUGEPAGE	14		/* Worth backing with hugepages */
+
 /* compatibility flags */
 #define MAP_FILE	0
 
diff --git a/arch/mips/include/asm/mman.h b/arch/mips/include/asm/mman.h
--- a/arch/mips/include/asm/mman.h
+++ b/arch/mips/include/asm/mman.h
@@ -77,6 +77,8 @@
 #define MADV_UNMERGEABLE 13		/* KSM may not merge identical pages */
 #define MADV_HWPOISON    100		/* poison a page for testing */
 
+#define MADV_HUGEPAGE	14		/* Worth backing with hugepages */
+
 /* compatibility flags */
 #define MAP_FILE	0
 
diff --git a/arch/parisc/include/asm/mman.h b/arch/parisc/include/asm/mman.h
--- a/arch/parisc/include/asm/mman.h
+++ b/arch/parisc/include/asm/mman.h
@@ -59,6 +59,8 @@
 #define MADV_MERGEABLE   65		/* KSM may merge identical pages */
 #define MADV_UNMERGEABLE 66		/* KSM may not merge identical pages */
 
+#define MADV_HUGEPAGE	67		/* Worth backing with hugepages */
+
 /* compatibility flags */
 #define MAP_FILE	0
 #define MAP_VARIABLE	0
diff --git a/arch/xtensa/include/asm/mman.h b/arch/xtensa/include/asm/mman.h
--- a/arch/xtensa/include/asm/mman.h
+++ b/arch/xtensa/include/asm/mman.h
@@ -83,6 +83,8 @@
 #define MADV_MERGEABLE   12		/* KSM may merge identical pages */
 #define MADV_UNMERGEABLE 13		/* KSM may not merge identical pages */
 
+#define MADV_HUGEPAGE	14		/* Worth backing with hugepages */
+
 /* compatibility flags */
 #define MAP_FILE	0
 
diff --git a/include/asm-generic/mman-common.h b/include/asm-generic/mman-common.h
--- a/include/asm-generic/mman-common.h
+++ b/include/asm-generic/mman-common.h
@@ -45,6 +45,8 @@
 #define MADV_MERGEABLE   12		/* KSM may merge identical pages */
 #define MADV_UNMERGEABLE 13		/* KSM may not merge identical pages */
 
+#define MADV_HUGEPAGE	14		/* Worth backing with hugepages */
+
 /* compatibility flags */
 #define MAP_FILE	0
 

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[PATCH 02 of 67] compound_lock

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Add a new compound_lock() needed to serialize put_page against
__split_huge_page_refcount().

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/include/linux/mm.h b/include/linux/mm.h
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -13,6 +13,7 @@
 #include <linux/debug_locks.h>
 #include <linux/mm_types.h>
 #include <linux/range.h>
+#include <linux/bit_spinlock.h>
 
 struct mempolicy;
 struct anon_vma;
@@ -297,6 +298,20 @@ static inline int is_vmalloc_or_module_a
 }
 #endif
 
+static inline void compound_lock(struct page *page)
+{
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	bit_spin_lock(PG_compound_lock, &page->flags);
+#endif
+}
+
+static inline void compound_unlock(struct page *page)
+{
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	bit_spin_unlock(PG_compound_lock, &page->flags);
+#endif
+}
+
 static inline struct page *compound_head(struct page *page)
 {
 	if (unlikely(PageTail(page)))
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -108,6 +108,9 @@ enum pageflags {
 #ifdef CONFIG_MEMORY_FAILURE
 	PG_hwpoison,		/* hardware poisoned page. Don't touch */
 #endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	PG_compound_lock,
+#endif
 	__NR_PAGEFLAGS,
 
 	/* Filesystems */
@@ -399,6 +402,12 @@ static inline void __ClearPageTail(struc
 #define __PG_MLOCKED		0
 #endif
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define __PG_COMPOUND_LOCK		(1 << PG_compound_lock)
+#else
+#define __PG_COMPOUND_LOCK		0
+#endif
+
 /*
  * Flags checked when a page is freed.  Pages being freed should not have
  * these flags set.  It they are, there is a problem.
@@ -408,7 +417,8 @@ static inline void __ClearPageTail(struc
 	 1 << PG_private | 1 << PG_private_2 | \
 	 1 << PG_buddy	 | 1 << PG_writeback | 1 << PG_reserved | \
 	 1 << PG_slab	 | 1 << PG_swapcache | 1 << PG_active | \
-	 1 << PG_unevictable | __PG_MLOCKED | __PG_HWPOISON)
+	 1 << PG_unevictable | __PG_MLOCKED | __PG_HWPOISON | \
+	 __PG_COMPOUND_LOCK)
 
 /*
  * Flags checked when a page is prepped for return by the page allocator.

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[PATCH 03 of 67] alter compound get_page/put_page

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Alter compound get_page/put_page to keep references on subpages too, in order
to allow __split_huge_page_refcount to split an hugepage even while subpages
have been pinned by one of the get_user_pages() variants.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/arch/powerpc/mm/gup.c b/arch/powerpc/mm/gup.c
--- a/arch/powerpc/mm/gup.c
+++ b/arch/powerpc/mm/gup.c
@@ -16,6 +16,16 @@
 
 #ifdef __HAVE_ARCH_PTE_SPECIAL
 
+static inline void pin_huge_page_tail(struct page *page)
+{
+	/*
+	 * __split_huge_page_refcount() cannot run
+	 * from under us.
+	 */
+	VM_BUG_ON(atomic_read(&page->_count) < 0);
+	atomic_inc(&page->_count);
+}
+
 /*
  * The performance critical leaf functions are made noinline otherwise gcc
  * inlines everything into a single function which results in too much
@@ -47,6 +57,8 @@ static noinline int gup_pte_range(pmd_t 
 			put_page(page);
 			return 0;
 		}
+		if (PageTail(page))
+			pin_huge_page_tail(page);
 		pages[*nr] = page;
 		(*nr)++;
 
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -105,6 +105,16 @@ static inline void get_head_page_multipl
 	atomic_add(nr, &page->_count);
 }
 
+static inline void pin_huge_page_tail(struct page *page)
+{
+	/*
+	 * __split_huge_page_refcount() cannot run
+	 * from under us.
+	 */
+	VM_BUG_ON(atomic_read(&page->_count) < 0);
+	atomic_inc(&page->_count);
+}
+
 static noinline int gup_huge_pmd(pmd_t pmd, unsigned long addr,
 		unsigned long end, int write, struct page **pages, int *nr)
 {
@@ -128,6 +138,8 @@ static noinline int gup_huge_pmd(pmd_t p
 	do {
 		VM_BUG_ON(compound_head(page) != head);
 		pages[*nr] = page;
+		if (PageTail(page))
+			pin_huge_page_tail(page);
 		(*nr)++;
 		page++;
 		refs++;
diff --git a/include/linux/mm.h b/include/linux/mm.h
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -326,9 +326,17 @@ static inline int page_count(struct page
 
 static inline void get_page(struct page *page)
 {
-	page = compound_head(page);
-	VM_BUG_ON(atomic_read(&page->_count) == 0);
+	VM_BUG_ON(atomic_read(&page->_count) < !PageTail(page));
 	atomic_inc(&page->_count);
+	if (unlikely(PageTail(page))) {
+		/*
+		 * This is safe only because
+		 * __split_huge_page_refcount can't run under
+		 * get_page().
+		 */
+		VM_BUG_ON(atomic_read(&page->first_page->_count) <= 0);
+		atomic_inc(&page->first_page->_count);
+	}
 }
 
 static inline struct page *virt_to_head_page(const void *x)
diff --git a/mm/swap.c b/mm/swap.c
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -56,17 +56,82 @@ static void __page_cache_release(struct 
 		del_page_from_lru(zone, page);
 		spin_unlock_irqrestore(&zone->lru_lock, flags);
 	}
+}
+
+static void __put_single_page(struct page *page)
+{
+	__page_cache_release(page);
 	free_hot_cold_page(page, 0);
 }
 
+static void __put_compound_page(struct page *page)
+{
+	compound_page_dtor *dtor;
+
+	__page_cache_release(page);
+	dtor = get_compound_page_dtor(page);
+	(*dtor)(page);
+}
+
 static void put_compound_page(struct page *page)
 {
-	page = compound_head(page);
-	if (put_page_testzero(page)) {
-		compound_page_dtor *dtor;
-
-		dtor = get_compound_page_dtor(page);
-		(*dtor)(page);
+	if (unlikely(PageTail(page))) {
+		/* __split_huge_page_refcount can run under us */
+		struct page *page_head = page->first_page;
+		smp_rmb();
+		if (likely(PageTail(page) && get_page_unless_zero(page_head))) {
+			if (unlikely(!PageHead(page_head))) {
+				/* PageHead is cleared after PageTail */
+				smp_rmb();
+				VM_BUG_ON(PageTail(page));
+				goto out_put_head;
+			}
+			/*
+			 * Only run compound_lock on a valid PageHead,
+			 * after having it pinned with
+			 * get_page_unless_zero() above.
+			 */
+			smp_mb();
+			/* page_head wasn't a dangling pointer */
+			compound_lock(page_head);
+			if (unlikely(!PageTail(page))) {
+				/* __split_huge_page_refcount run before us */
+				compound_unlock(page_head);
+				VM_BUG_ON(PageHead(page_head));
+			out_put_head:
+				if (put_page_testzero(page_head))
+					__put_single_page(page_head);
+			out_put_single:
+				if (put_page_testzero(page))
+					__put_single_page(page);
+				return;
+			}
+			VM_BUG_ON(page_head != page->first_page);
+			/*
+			 * We can release the refcount taken by
+			 * get_page_unless_zero now that
+			 * split_huge_page_refcount is blocked on the
+			 * compound_lock.
+			 */
+			if (put_page_testzero(page_head))
+				VM_BUG_ON(1);
+			/* __split_huge_page_refcount will wait now */
+			VM_BUG_ON(atomic_read(&page->_count) <= 0);
+			atomic_dec(&page->_count);
+			VM_BUG_ON(atomic_read(&page_head->_count) <= 0);
+			compound_unlock(page_head);
+			if (put_page_testzero(page_head))
+				__put_compound_page(page_head);
+		} else {
+			/* page_head is a dangling pointer */
+			VM_BUG_ON(PageTail(page));
+			goto out_put_single;
+		}
+	} else if (put_page_testzero(page)) {
+		if (PageHead(page))
+			__put_compound_page(page);
+		else
+			__put_single_page(page);
 	}
 }
 
@@ -75,7 +140,7 @@ void put_page(struct page *page)
 	if (unlikely(PageCompound(page)))
 		put_compound_page(page);
 	else if (put_page_testzero(page))
-		__page_cache_release(page);
+		__put_single_page(page);
 }
 EXPORT_SYMBOL(put_page);
 

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[PATCH 04 of 67] update futex compound knowledge

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Futex code is smarter than most other gup_fast O_DIRECT code and knows about
the compound internals. However now doing a put_page(head_page) will not
release the pin on the tail page taken by gup-fast, leading to all sort of
refcounting bugchecks. Getting a stable head_page is a little tricky.

page_head = page is there because if this is not a tail page it's also the
page_head. Only in case this is a tail page, compound_head is called, otherwise
it's guaranteed unnecessary. And if it's a tail page compound_head has to run
atomically inside irq disabled section __get_user_pages_fast before returning.
Otherwise ->first_page won't be a stable pointer.

Disableing irq before __get_user_page_fast and releasing irq after running
compound_head is needed because if __get_user_page_fast returns == 1, it means
the huge pmd is established and cannot go away from under us.
pmdp_splitting_flush_notify in __split_huge_page_splitting will have to wait
for local_irq_enable before the IPI delivery can return. This means
__split_huge_page_refcount can't be running from under us, and in turn when we
run compound_head(page) we're not reading a dangling pointer from
tailpage->first_page. Then after we get to stable head page, we are always safe
to call compound_lock and after taking the compound lock on head page we can
finally re-check if the page returned by gup-fast is still a tail page. in
which case we're set and we didn't need to split the hugepage in order to take
a futex on it.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/kernel/futex.c b/kernel/futex.c
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -218,7 +218,7 @@ get_futex_key(u32 __user *uaddr, int fsh
 {
 	unsigned long address = (unsigned long)uaddr;
 	struct mm_struct *mm = current->mm;
-	struct page *page;
+	struct page *page, *page_head;
 	int err;
 
 	/*
@@ -250,10 +250,53 @@ again:
 	if (err < 0)
 		return err;
 
-	page = compound_head(page);
-	lock_page(page);
-	if (!page->mapping) {
-		unlock_page(page);
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	page_head = page;
+	if (unlikely(PageTail(page))) {
+		put_page(page);
+		/* serialize against __split_huge_page_splitting() */
+		local_irq_disable();
+		if (likely(__get_user_pages_fast(address, 1, 1, &page) == 1)) {
+			page_head = compound_head(page);
+			/*
+			 * page_head is valid pointer but we must pin
+			 * it before taking the PG_lock and/or
+			 * PG_compound_lock. The moment we re-enable
+			 * irqs __split_huge_page_splitting() can
+			 * return and the head page can be freed from
+			 * under us. We can't take the PG_lock and/or
+			 * PG_compound_lock on a page that could be
+			 * freed from under us.
+			 */
+			if (page != page_head)
+				get_page(page_head);
+			local_irq_enable();
+		} else {
+			local_irq_enable();
+			goto again;
+		}
+	}
+#else
+	page_head = compound_head(page);
+	if (page != page_head)
+		get_page(page_head);
+#endif
+
+	lock_page(page_head);
+	if (unlikely(page_head != page)) {
+		compound_lock(page_head);
+		if (unlikely(!PageTail(page))) {
+			compound_unlock(page_head);
+			unlock_page(page_head);
+			put_page(page_head);
+			put_page(page);
+			goto again;
+		}
+	}
+	if (!page_head->mapping) {
+		unlock_page(page_head);
+		if (page_head != page)
+			put_page(page_head);
 		put_page(page);
 		goto again;
 	}
@@ -265,19 +308,25 @@ again:
 	 * it's a read-only handle, it's expected that futexes attach to
 	 * the object not the particular process.
 	 */
-	if (PageAnon(page)) {
+	if (PageAnon(page_head)) {
 		key->both.offset |= FUT_OFF_MMSHARED; /* ref taken on mm */
 		key->private.mm = mm;
 		key->private.address = address;
 	} else {
 		key->both.offset |= FUT_OFF_INODE; /* inode-based key */
-		key->shared.inode = page->mapping->host;
-		key->shared.pgoff = page->index;
+		key->shared.inode = page_head->mapping->host;
+		key->shared.pgoff = page_head->index;
 	}
 
 	get_futex_key_refs(key);
 
-	unlock_page(page);
+	unlock_page(page_head);
+	if (page != page_head) {
+		VM_BUG_ON(!PageTail(page));
+		/* releasing compound_lock after page_lock won't matter */
+		compound_unlock(page_head);
+		put_page(page_head);
+	}
 	put_page(page);
 	return 0;
 }

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[PATCH 05 of 67] fix bad_page to show the real reason the page is bad

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

page_count shows the count of the head page, but the actual check is done on
the tail page, so show what is really being checked.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
---

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5254,7 +5254,7 @@ void dump_page(struct page *page)
 {
 	printk(KERN_ALERT
 	       "page:%p count:%d mapcount:%d mapping:%p index:%#lx\n",
-		page, page_count(page), page_mapcount(page),
+		page, atomic_read(&page->_count), page_mapcount(page),
 		page->mapping, page->index);
 	dump_page_flags(page->flags);
 }

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[PATCH 06 of 67] clear compound mapping

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Clear compound mapping for anonymous compound pages like it already happens for
regular anonymous pages.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
---

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -609,6 +609,8 @@ static void __free_pages_ok(struct page 
 	trace_mm_page_free_direct(page, order);
 	kmemcheck_free_shadow(page, order);
 
+	if (PageAnon(page))
+		page->mapping = NULL;
 	for (i = 0 ; i < (1 << order) ; ++i)
 		bad += free_pages_check(page + i);
 	if (bad)

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[PATCH 07 of 67] add native_set_pmd_at

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Used by paravirt and not paravirt set_pmd_at.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
---

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -528,6 +528,12 @@ static inline void native_set_pte_at(str
 	native_set_pte(ptep, pte);
 }
 
+static inline void native_set_pmd_at(struct mm_struct *mm, unsigned long addr,
+				     pmd_t *pmdp , pmd_t pmd)
+{
+	native_set_pmd(pmdp, pmd);
+}
+
 #ifndef CONFIG_PARAVIRT
 /*
  * Rules for using pte_update - it must be called after any PTE update which

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[PATCH 08 of 67] add pmd paravirt ops

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Paravirt ops pmd_update/pmd_update_defer/pmd_set_at. Not all might be necessary
(vmware needs pmd_update, Xen needs set_pmd_at, nobody needs pmd_update_defer),
but this is to keep full simmetry with pte paravirt ops, which looks cleaner
and simpler from a common code POV.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
---

diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -440,6 +440,11 @@ static inline void pte_update(struct mm_
 {
 	PVOP_VCALL3(pv_mmu_ops.pte_update, mm, addr, ptep);
 }
+static inline void pmd_update(struct mm_struct *mm, unsigned long addr,
+			      pmd_t *pmdp)
+{
+	PVOP_VCALL3(pv_mmu_ops.pmd_update, mm, addr, pmdp);
+}
 
 static inline void pte_update_defer(struct mm_struct *mm, unsigned long addr,
 				    pte_t *ptep)
@@ -447,6 +452,12 @@ static inline void pte_update_defer(stru
 	PVOP_VCALL3(pv_mmu_ops.pte_update_defer, mm, addr, ptep);
 }
 
+static inline void pmd_update_defer(struct mm_struct *mm, unsigned long addr,
+				    pmd_t *pmdp)
+{
+	PVOP_VCALL3(pv_mmu_ops.pmd_update_defer, mm, addr, pmdp);
+}
+
 static inline pte_t __pte(pteval_t val)
 {
 	pteval_t ret;
@@ -548,6 +559,18 @@ static inline void set_pte_at(struct mm_
 		PVOP_VCALL4(pv_mmu_ops.set_pte_at, mm, addr, ptep, pte.pte);
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
+			      pmd_t *pmdp, pmd_t pmd)
+{
+	if (sizeof(pmdval_t) > sizeof(long))
+		/* 5 arg words */
+		pv_mmu_ops.set_pmd_at(mm, addr, pmdp, pmd);
+	else
+		PVOP_VCALL4(pv_mmu_ops.set_pmd_at, mm, addr, pmdp, pmd.pmd);
+}
+#endif
+
 static inline void set_pmd(pmd_t *pmdp, pmd_t pmd)
 {
 	pmdval_t val = native_pmd_val(pmd);
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -266,10 +266,16 @@ struct pv_mmu_ops {
 	void (*set_pte_at)(struct mm_struct *mm, unsigned long addr,
 			   pte_t *ptep, pte_t pteval);
 	void (*set_pmd)(pmd_t *pmdp, pmd_t pmdval);
+	void (*set_pmd_at)(struct mm_struct *mm, unsigned long addr,
+			   pmd_t *pmdp, pmd_t pmdval);
 	void (*pte_update)(struct mm_struct *mm, unsigned long addr,
 			   pte_t *ptep);
 	void (*pte_update_defer)(struct mm_struct *mm,
 				 unsigned long addr, pte_t *ptep);
+	void (*pmd_update)(struct mm_struct *mm, unsigned long addr,
+			   pmd_t *pmdp);
+	void (*pmd_update_defer)(struct mm_struct *mm,
+				 unsigned long addr, pmd_t *pmdp);
 
 	pte_t (*ptep_modify_prot_start)(struct mm_struct *mm, unsigned long addr,
 					pte_t *ptep);
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -422,8 +422,11 @@ struct pv_mmu_ops pv_mmu_ops = {
 	.set_pte = native_set_pte,
 	.set_pte_at = native_set_pte_at,
 	.set_pmd = native_set_pmd,
+	.set_pmd_at = native_set_pmd_at,
 	.pte_update = paravirt_nop,
 	.pte_update_defer = paravirt_nop,
+	.pmd_update = paravirt_nop,
+	.pmd_update_defer = paravirt_nop,
 
 	.ptep_modify_prot_start = __ptep_modify_prot_start,
 	.ptep_modify_prot_commit = __ptep_modify_prot_commit,

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[PATCH 09 of 67] no paravirt version of pmd ops

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

No paravirt version of set_pmd_at/pmd_update/pmd_update_defer.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
---

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -33,6 +33,7 @@ extern struct list_head pgd_list;
 #else  /* !CONFIG_PARAVIRT */
 #define set_pte(ptep, pte)		native_set_pte(ptep, pte)
 #define set_pte_at(mm, addr, ptep, pte)	native_set_pte_at(mm, addr, ptep, pte)
+#define set_pmd_at(mm, addr, pmdp, pmd)	native_set_pmd_at(mm, addr, pmdp, pmd)
 
 #define set_pte_atomic(ptep, pte)					\
 	native_set_pte_atomic(ptep, pte)
@@ -57,6 +58,8 @@ extern struct list_head pgd_list;
 
 #define pte_update(mm, addr, ptep)              do { } while (0)
 #define pte_update_defer(mm, addr, ptep)        do { } while (0)
+#define pmd_update(mm, addr, ptep)              do { } while (0)
+#define pmd_update_defer(mm, addr, ptep)        do { } while (0)
 
 #define pgd_val(x)	native_pgd_val(x)
 #define __pgd(x)	native_make_pgd(x)

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[PATCH 10 of 67] export maybe_mkwrite

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

huge_memory.c needs it too when it fallbacks in copying hugepages into regular
fragmented pages if hugepage allocation fails during COW.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
---

diff --git a/include/linux/mm.h b/include/linux/mm.h
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -390,6 +390,19 @@ static inline void set_compound_order(st
 }
 
 /*
+ * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
+ * servicing faults for write access.  In the normal case, do always want
+ * pte_mkwrite.  But get_user_pages can cause write faults for mappings
+ * that do not have writing enabled, when used by access_process_vm.
+ */
+static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
+{
+	if (likely(vma->vm_flags & VM_WRITE))
+		pte = pte_mkwrite(pte);
+	return pte;
+}
+
+/*
  * Multiple processes may "see" the same page. E.g. for untouched
  * mappings of /dev/null, all processes see the same page full of
  * zeroes, and text pages of executables and shared libraries have
diff --git a/mm/memory.c b/mm/memory.c
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2031,19 +2031,6 @@ static inline int pte_unmap_same(struct 
 	return same;
 }
 
-/*
- * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
- * servicing faults for write access.  In the normal case, do always want
- * pte_mkwrite.  But get_user_pages can cause write faults for mappings
- * that do not have writing enabled, when used by access_process_vm.
- */
-static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)
-{
-	if (likely(vma->vm_flags & VM_WRITE))
-		pte = pte_mkwrite(pte);
-	return pte;
-}
-
 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
 {
 	/*

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[PATCH 11 of 67] comment reminder in destroy_compound_page

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Warn destroy_compound_page that __split_huge_page_refcount is heavily dependent
on its internal behavior.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
---

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -334,6 +334,7 @@ void prep_compound_page(struct page *pag
 	}
 }
 
+/* update __split_huge_page_refcount if you change this function */
 static int destroy_compound_page(struct page *page, unsigned long order)
 {
 	int i;

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[PATCH 12 of 67] config_transparent_hugepage

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Add config option.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
---

diff --git a/fs/Kconfig b/fs/Kconfig
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -145,7 +145,7 @@ config HUGETLBFS
 	  If unsure, say N.
 
 config HUGETLB_PAGE
-	def_bool HUGETLBFS
+	def_bool HUGETLBFS || TRANSPARENT_HUGEPAGE
 
 source "fs/configfs/Kconfig"
 
diff --git a/mm/Kconfig b/mm/Kconfig
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -287,3 +287,17 @@ config NOMMU_INITIAL_TRIM_EXCESS
 	  of 1 says that all excess pages should be trimmed.
 
 	  See Documentation/nommu-mmap.txt for more information.
+
+config TRANSPARENT_HUGEPAGE
+	bool "Transparent Hugepage support" if EMBEDDED
+	depends on X86_64 && MMU
+	default y
+	help
+	  Transparent Hugepages allows the kernel to use huge pages and
+	  huge tlb transparently to the applications whenever possible.
+	  This feature can improve computing performance to certain
+	  applications by speeding up page faults during memory
+	  allocation, by reducing the number of tlb misses and by speeding
+	  up the pagetable walking.
+
+	  If memory constrained on embedded, you may want to say N.

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[PATCH 13 of 67] special pmd_trans_* functions

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

These returns 0 at compile time when the config option is disabled, to allow
gcc to eliminate the transparent hugepage function calls at compile time
without additional #ifdefs (only the export of those functions have to be
visible to gcc but they won't be required at link time and huge_memory.o can be
not built at all).

_PAGE_BIT_UNUSED1 is never used for pmd, only on pte.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -168,6 +168,19 @@ extern void cleanup_highmap(void);
 #define	kc_offset_to_vaddr(o) ((o) | ~__VIRTUAL_MASK)
 
 #define __HAVE_ARCH_PTE_SAME
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline int pmd_trans_splitting(pmd_t pmd)
+{
+	return pmd_val(pmd) & _PAGE_SPLITTING;
+}
+
+static inline int pmd_trans_huge(pmd_t pmd)
+{
+	return pmd_val(pmd) & _PAGE_PSE;
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* _ASM_X86_PGTABLE_64_H */
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -22,6 +22,7 @@
 #define _PAGE_BIT_PAT_LARGE	12	/* On 2MB or 1GB pages */
 #define _PAGE_BIT_SPECIAL	_PAGE_BIT_UNUSED1
 #define _PAGE_BIT_CPA_TEST	_PAGE_BIT_UNUSED1
+#define _PAGE_BIT_SPLITTING	_PAGE_BIT_UNUSED1 /* only valid on a PSE pmd */
 #define _PAGE_BIT_NX           63       /* No execute: only valid after cpuid check */
 
 /* If _PAGE_BIT_PRESENT is clear, we use these: */
@@ -45,6 +46,7 @@
 #define _PAGE_PAT_LARGE (_AT(pteval_t, 1) << _PAGE_BIT_PAT_LARGE)
 #define _PAGE_SPECIAL	(_AT(pteval_t, 1) << _PAGE_BIT_SPECIAL)
 #define _PAGE_CPA_TEST	(_AT(pteval_t, 1) << _PAGE_BIT_CPA_TEST)
+#define _PAGE_SPLITTING	(_AT(pteval_t, 1) << _PAGE_BIT_SPLITTING)
 #define __HAVE_ARCH_PTE_SPECIAL
 
 #ifdef CONFIG_KMEMCHECK
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -344,6 +344,11 @@ extern void untrack_pfn_vma(struct vm_ar
 				unsigned long size);
 #endif
 
+#ifndef CONFIG_TRANSPARENT_HUGEPAGE
+#define pmd_trans_huge(pmd) 0
+#define pmd_trans_splitting(pmd) 0
+#endif
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* _ASM_GENERIC_PGTABLE_H */

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[PATCH 14 of 67] add pmd mangling generic functions

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Some are needed to build but not actually used on archs not supporting
transparent hugepages. Others like pmdp_clear_flush are used by x86 too.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -25,6 +25,26 @@
 })
 #endif
 
+#ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define pmdp_set_access_flags(__vma, __address, __pmdp, __entry, __dirty) \
+	({								\
+		int __changed = !pmd_same(*(__pmdp), __entry);		\
+		VM_BUG_ON((__address) & ~HPAGE_PMD_MASK);		\
+		if (__changed) {					\
+			set_pmd_at((__vma)->vm_mm, __address, __pmdp,	\
+				   __entry);				\
+			flush_tlb_range(__vma, __address,		\
+					(__address) + HPAGE_PMD_SIZE);	\
+		}							\
+		__changed;						\
+	})
+#else /* CONFIG_TRANSPARENT_HUGEPAGE */
+#define pmdp_set_access_flags(__vma, __address, __pmdp, __entry, __dirty) \
+	({ BUG(); 0; })
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif
+
 #ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
 #define ptep_test_and_clear_young(__vma, __address, __ptep)		\
 ({									\
@@ -39,6 +59,25 @@
 })
 #endif
 
+#ifndef __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define pmdp_test_and_clear_young(__vma, __address, __pmdp)		\
+({									\
+	pmd_t __pmd = *(__pmdp);					\
+	int r = 1;							\
+	if (!pmd_young(__pmd))						\
+		r = 0;							\
+	else								\
+		set_pmd_at((__vma)->vm_mm, (__address),			\
+			   (__pmdp), pmd_mkold(__pmd));			\
+	r;								\
+})
+#else /* CONFIG_TRANSPARENT_HUGEPAGE */
+#define pmdp_test_and_clear_young(__vma, __address, __pmdp)	\
+	({ BUG(); 0; })
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif
+
 #ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
 #define ptep_clear_flush_young(__vma, __address, __ptep)		\
 ({									\
@@ -50,6 +89,24 @@
 })
 #endif
 
+#ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define pmdp_clear_flush_young(__vma, __address, __pmdp)		\
+({									\
+	int __young;							\
+	VM_BUG_ON((__address) & ~HPAGE_PMD_MASK);			\
+	__young = pmdp_test_and_clear_young(__vma, __address, __pmdp);	\
+	if (__young)							\
+		flush_tlb_range(__vma, __address,			\
+				(__address) + HPAGE_PMD_SIZE);		\
+	__young;							\
+})
+#else /* CONFIG_TRANSPARENT_HUGEPAGE */
+#define pmdp_clear_flush_young(__vma, __address, __pmdp)	\
+	({ BUG(); 0; })
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif
+
 #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR
 #define ptep_get_and_clear(__mm, __address, __ptep)			\
 ({									\
@@ -59,6 +116,20 @@
 })
 #endif
 
+#ifndef __HAVE_ARCH_PMDP_GET_AND_CLEAR
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define pmdp_get_and_clear(__mm, __address, __pmdp)			\
+({									\
+	pmd_t __pmd = *(__pmdp);					\
+	pmd_clear((__mm), (__address), (__pmdp));			\
+	__pmd;								\
+})
+#else /* CONFIG_TRANSPARENT_HUGEPAGE */
+#define pmdp_get_and_clear(__mm, __address, __pmdp)	\
+	({ BUG(); 0; })
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif
+
 #ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL
 #define ptep_get_and_clear_full(__mm, __address, __ptep, __full)	\
 ({									\
@@ -90,6 +161,22 @@ do {									\
 })
 #endif
 
+#ifndef __HAVE_ARCH_PMDP_CLEAR_FLUSH
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define pmdp_clear_flush(__vma, __address, __pmdp)			\
+({									\
+	pmd_t __pmd;							\
+	VM_BUG_ON((__address) & ~HPAGE_PMD_MASK);			\
+	__pmd = pmdp_get_and_clear((__vma)->vm_mm, __address, __pmdp);	\
+	flush_tlb_range(__vma, __address, (__address) + HPAGE_PMD_SIZE);\
+	__pmd;								\
+})
+#else /* CONFIG_TRANSPARENT_HUGEPAGE */
+#define pmdp_clear_flush(__vma, __address, __pmdp)	\
+	({ BUG(); 0; })
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif
+
 #ifndef __HAVE_ARCH_PTEP_SET_WRPROTECT
 struct mm_struct;
 static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long address, pte_t *ptep)
@@ -99,10 +186,45 @@ static inline void ptep_set_wrprotect(st
 }
 #endif
 
+#ifndef __HAVE_ARCH_PMDP_SET_WRPROTECT
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline void pmdp_set_wrprotect(struct mm_struct *mm, unsigned long address, pmd_t *pmdp)
+{
+	pmd_t old_pmd = *pmdp;
+	set_pmd_at(mm, address, pmdp, pmd_wrprotect(old_pmd));
+}
+#else /* CONFIG_TRANSPARENT_HUGEPAGE */
+#define pmdp_set_wrprotect(mm, address, pmdp) BUG()
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif
+
+#ifndef __HAVE_ARCH_PMDP_SPLITTING_FLUSH
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define pmdp_splitting_flush(__vma, __address, __pmdp)			\
+({									\
+	pmd_t __pmd = pmd_mksplitting(*(__pmdp));			\
+	VM_BUG_ON((__address) & ~HPAGE_PMD_MASK);			\
+	set_pmd_at((__vma)->vm_mm, __address, __pmdp, __pmd);		\
+	/* tlb flush only to serialize against gup-fast */		\
+	flush_tlb_range(__vma, __address, (__address) + HPAGE_PMD_SIZE);\
+})
+#else /* CONFIG_TRANSPARENT_HUGEPAGE */
+#define pmdp_splitting_flush(__vma, __address, __pmdp) BUG()
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif
+
 #ifndef __HAVE_ARCH_PTE_SAME
 #define pte_same(A,B)	(pte_val(A) == pte_val(B))
 #endif
 
+#ifndef __HAVE_ARCH_PMD_SAME
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define pmd_same(A,B)	(pmd_val(A) == pmd_val(B))
+#else /* CONFIG_TRANSPARENT_HUGEPAGE */
+#define pmd_same(A,B)	({ BUG(); 0; })
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+#endif
+
 #ifndef __HAVE_ARCH_PAGE_TEST_DIRTY
 #define page_test_dirty(page)		(0)
 #endif
@@ -347,6 +469,9 @@ extern void untrack_pfn_vma(struct vm_ar
 #ifndef CONFIG_TRANSPARENT_HUGEPAGE
 #define pmd_trans_huge(pmd) 0
 #define pmd_trans_splitting(pmd) 0
+#ifndef __HAVE_ARCH_PMD_WRITE
+#define pmd_write(pmd)	({ BUG(); 0; })
+#endif /* __HAVE_ARCH_PMD_WRITE */
 #endif
 
 #endif /* !__ASSEMBLY__ */

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[PATCH 15 of 67] add pmd mangling functions to x86

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Add needed pmd mangling functions with simmetry with their pte counterparts.
pmdp_freeze_flush is the only exception only present on the pmd side and it's
needed to serialize the VM against split_huge_page, it simply atomically clears
the present bit in the same way pmdp_clear_flush_young atomically clears the
accessed bit (and both need to flush the tlb to make it effective, which is
mandatory to happen synchronously for pmdp_freeze_flush).

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -300,15 +300,15 @@ pmd_t *populate_extra_pmd(unsigned long 
 pte_t *populate_extra_pte(unsigned long vaddr);
 #endif	/* __ASSEMBLY__ */
 
+#ifndef __ASSEMBLY__
+#include <linux/mm_types.h>
+
 #ifdef CONFIG_X86_32
 # include "pgtable_32.h"
 #else
 # include "pgtable_64.h"
 #endif
 
-#ifndef __ASSEMBLY__
-#include <linux/mm_types.h>
-
 static inline int pte_none(pte_t pte)
 {
 	return !pte.pte;
@@ -351,7 +351,7 @@ static inline unsigned long pmd_page_vad
  * Currently stuck as a macro due to indirect forward reference to
  * linux/mmzone.h's __section_mem_map_addr() definition:
  */
-#define pmd_page(pmd)	pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)
+#define pmd_page(pmd)	pfn_to_page((pmd_val(pmd) & PTE_PFN_MASK) >> PAGE_SHIFT)
 
 /*
  * the pmd page can be thought of an array like this: pmd_t[PTRS_PER_PMD]
diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -72,6 +72,19 @@ static inline pte_t native_ptep_get_and_
 #endif
 }
 
+static inline pmd_t native_pmdp_get_and_clear(pmd_t *xp)
+{
+#ifdef CONFIG_SMP
+	return native_make_pmd(xchg(&xp->pmd, 0));
+#else
+	/* native_local_pmdp_get_and_clear,
+	   but duplicated because of cyclic dependency */
+	pmd_t ret = *xp;
+	native_pmd_clear(NULL, 0, xp);
+	return ret;
+#endif
+}
+
 static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)
 {
 	*pmdp = pmd;
@@ -181,6 +194,98 @@ static inline int pmd_trans_huge(pmd_t p
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
+#define mk_pmd(page, pgprot)   pfn_pmd(page_to_pfn(page), (pgprot))
+
+#define  __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
+extern int pmdp_set_access_flags(struct vm_area_struct *vma,
+				 unsigned long address, pmd_t *pmdp,
+				 pmd_t entry, int dirty);
+
+#define __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG
+extern int pmdp_test_and_clear_young(struct vm_area_struct *vma,
+				     unsigned long addr, pmd_t *pmdp);
+
+#define __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
+extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
+				  unsigned long address, pmd_t *pmdp);
+
+
+#define __HAVE_ARCH_PMDP_SPLITTING_FLUSH
+extern void pmdp_splitting_flush(struct vm_area_struct *vma,
+				 unsigned long addr, pmd_t *pmdp);
+
+#define __HAVE_ARCH_PMD_WRITE
+static inline int pmd_write(pmd_t pmd)
+{
+	return pmd_flags(pmd) & _PAGE_RW;
+}
+
+#define __HAVE_ARCH_PMDP_GET_AND_CLEAR
+static inline pmd_t pmdp_get_and_clear(struct mm_struct *mm, unsigned long addr,
+				       pmd_t *pmdp)
+{
+	pmd_t pmd = native_pmdp_get_and_clear(pmdp);
+	pmd_update(mm, addr, pmdp);
+	return pmd;
+}
+
+#define __HAVE_ARCH_PMDP_SET_WRPROTECT
+static inline void pmdp_set_wrprotect(struct mm_struct *mm,
+				      unsigned long addr, pmd_t *pmdp)
+{
+	clear_bit(_PAGE_BIT_RW, (unsigned long *)&pmdp->pmd);
+	pmd_update(mm, addr, pmdp);
+}
+
+static inline int pmd_young(pmd_t pmd)
+{
+	return pmd_flags(pmd) & _PAGE_ACCESSED;
+}
+
+static inline pmd_t pmd_set_flags(pmd_t pmd, pmdval_t set)
+{
+	pmdval_t v = native_pmd_val(pmd);
+
+	return native_make_pmd(v | set);
+}
+
+static inline pmd_t pmd_clear_flags(pmd_t pmd, pmdval_t clear)
+{
+	pmdval_t v = native_pmd_val(pmd);
+
+	return native_make_pmd(v & ~clear);
+}
+
+static inline pmd_t pmd_mkold(pmd_t pmd)
+{
+	return pmd_clear_flags(pmd, _PAGE_ACCESSED);
+}
+
+static inline pmd_t pmd_wrprotect(pmd_t pmd)
+{
+	return pmd_clear_flags(pmd, _PAGE_RW);
+}
+
+static inline pmd_t pmd_mkdirty(pmd_t pmd)
+{
+	return pmd_set_flags(pmd, _PAGE_DIRTY);
+}
+
+static inline pmd_t pmd_mkhuge(pmd_t pmd)
+{
+	return pmd_set_flags(pmd, _PAGE_PSE);
+}
+
+static inline pmd_t pmd_mkyoung(pmd_t pmd)
+{
+	return pmd_set_flags(pmd, _PAGE_ACCESSED);
+}
+
+static inline pmd_t pmd_mkwrite(pmd_t pmd)
+{
+	return pmd_set_flags(pmd, _PAGE_RW);
+}
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* _ASM_X86_PGTABLE_64_H */
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -310,6 +310,25 @@ int ptep_set_access_flags(struct vm_area
 	return changed;
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+int pmdp_set_access_flags(struct vm_area_struct *vma,
+			  unsigned long address, pmd_t *pmdp,
+			  pmd_t entry, int dirty)
+{
+	int changed = !pmd_same(*pmdp, entry);
+
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+
+	if (changed && dirty) {
+		*pmdp = entry;
+		pmd_update_defer(vma->vm_mm, address, pmdp);
+		flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+	}
+
+	return changed;
+}
+#endif
+
 int ptep_test_and_clear_young(struct vm_area_struct *vma,
 			      unsigned long addr, pte_t *ptep)
 {
@@ -325,6 +344,23 @@ int ptep_test_and_clear_young(struct vm_
 	return ret;
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+int pmdp_test_and_clear_young(struct vm_area_struct *vma,
+			      unsigned long addr, pmd_t *pmdp)
+{
+	int ret = 0;
+
+	if (pmd_young(*pmdp))
+		ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
+					 (unsigned long *) &pmdp->pmd);
+
+	if (ret)
+		pmd_update(vma->vm_mm, addr, pmdp);
+
+	return ret;
+}
+#endif
+
 int ptep_clear_flush_young(struct vm_area_struct *vma,
 			   unsigned long address, pte_t *ptep)
 {
@@ -337,6 +373,36 @@ int ptep_clear_flush_young(struct vm_are
 	return young;
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+int pmdp_clear_flush_young(struct vm_area_struct *vma,
+			   unsigned long address, pmd_t *pmdp)
+{
+	int young;
+
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+
+	young = pmdp_test_and_clear_young(vma, address, pmdp);
+	if (young)
+		flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+
+	return young;
+}
+
+void pmdp_splitting_flush(struct vm_area_struct *vma,
+			  unsigned long address, pmd_t *pmdp)
+{
+	int set;
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+	set = !test_and_set_bit(_PAGE_BIT_SPLITTING,
+				(unsigned long *)&pmdp->pmd);
+	if (set) {
+		pmd_update(vma->vm_mm, address, pmdp);
+		/* need tlb flush only to serialize against gup-fast */
+		flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+	}
+}
+#endif
+
 /**
  * reserve_top_address - reserves a hole in the top of kernel address space
  * @reserve - size of hole to reserve

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[PATCH 16 of 67] bail out gup_fast on splitting pmd

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Force gup_fast to take the slow path and block if the pmd is splitting, not
only if it's none.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
---

diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -160,7 +160,18 @@ static int gup_pmd_range(pud_t pud, unsi
 		pmd_t pmd = *pmdp;
 
 		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
+		/*
+		 * The pmd_trans_splitting() check below explains why
+		 * pmdp_splitting_flush has to flush the tlb, to stop
+		 * this gup-fast code from running while we set the
+		 * splitting bit in the pmd. Returning zero will take
+		 * the slow path that will call wait_split_huge_page()
+		 * if the pmd is still in splitting state. gup-fast
+		 * can't because it has irq disabled and
+		 * wait_split_huge_page() would never return as the
+		 * tlb flush IPI wouldn't run.
+		 */
+		if (pmd_none(pmd) || pmd_trans_splitting(pmd))
 			return 0;
 		if (unlikely(pmd_large(pmd))) {
 			if (!gup_huge_pmd(pmd, addr, next, write, pages, nr))

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[PATCH 17 of 67] pte alloc trans splitting

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

pte alloc routines must wait for split_huge_page if the pmd is not
present and not null (i.e. pmd_trans_splitting). The additional
branches are optimized away at compile time by pmd_trans_splitting if
the config option is off. However we must pass the vma down in order
to know the anon_vma lock to wait for.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
---

diff --git a/include/linux/mm.h b/include/linux/mm.h
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1066,7 +1066,8 @@ static inline int __pmd_alloc(struct mm_
 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address);
 #endif
 
-int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address);
+int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
+		pmd_t *pmd, unsigned long address);
 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address);
 
 /*
@@ -1135,12 +1136,14 @@ static inline void pgtable_page_dtor(str
 	pte_unmap(pte);					\
 } while (0)
 
-#define pte_alloc_map(mm, pmd, address)			\
-	((unlikely(!pmd_present(*(pmd))) && __pte_alloc(mm, pmd, address))? \
-		NULL: pte_offset_map(pmd, address))
+#define pte_alloc_map(mm, vma, pmd, address)				\
+	((unlikely(!pmd_present(*(pmd))) && __pte_alloc(mm, vma,	\
+							pmd, address))?	\
+	 NULL: pte_offset_map(pmd, address))
 
 #define pte_alloc_map_lock(mm, pmd, address, ptlp)	\
-	((unlikely(!pmd_present(*(pmd))) && __pte_alloc(mm, pmd, address))? \
+	((unlikely(!pmd_present(*(pmd))) && __pte_alloc(mm, NULL,	\
+							pmd, address))?	\
 		NULL: pte_offset_map_lock(mm, pmd, address, ptlp))
 
 #define pte_alloc_kernel(pmd, address)			\
diff --git a/mm/memory.c b/mm/memory.c
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -396,9 +396,11 @@ void free_pgtables(struct mmu_gather *tl
 	}
 }
 
-int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
+int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
+		pmd_t *pmd, unsigned long address)
 {
 	pgtable_t new = pte_alloc_one(mm, address);
+	int wait_split_huge_page;
 	if (!new)
 		return -ENOMEM;
 
@@ -418,14 +420,18 @@ int __pte_alloc(struct mm_struct *mm, pm
 	smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
 
 	spin_lock(&mm->page_table_lock);
-	if (!pmd_present(*pmd)) {	/* Has another populated it ? */
+	wait_split_huge_page = 0;
+	if (likely(pmd_none(*pmd))) {	/* Has another populated it ? */
 		mm->nr_ptes++;
 		pmd_populate(mm, pmd, new);
 		new = NULL;
-	}
+	} else if (unlikely(pmd_trans_splitting(*pmd)))
+		wait_split_huge_page = 1;
 	spin_unlock(&mm->page_table_lock);
 	if (new)
 		pte_free(mm, new);
+	if (wait_split_huge_page)
+		wait_split_huge_page(vma->anon_vma, pmd);
 	return 0;
 }
 
@@ -438,10 +444,11 @@ int __pte_alloc_kernel(pmd_t *pmd, unsig
 	smp_wmb(); /* See comment in __pte_alloc */
 
 	spin_lock(&init_mm.page_table_lock);
-	if (!pmd_present(*pmd)) {	/* Has another populated it ? */
+	if (likely(pmd_none(*pmd))) {	/* Has another populated it ? */
 		pmd_populate_kernel(&init_mm, pmd, new);
 		new = NULL;
-	}
+	} else
+		VM_BUG_ON(pmd_trans_splitting(*pmd));
 	spin_unlock(&init_mm.page_table_lock);
 	if (new)
 		pte_free_kernel(&init_mm, new);
@@ -3119,7 +3126,7 @@ int handle_mm_fault(struct mm_struct *mm
 	pmd = pmd_alloc(mm, pud, address);
 	if (!pmd)
 		return VM_FAULT_OOM;
-	pte = pte_alloc_map(mm, pmd, address);
+	pte = pte_alloc_map(mm, vma, pmd, address);
 	if (!pte)
 		return VM_FAULT_OOM;
 
diff --git a/mm/mremap.c b/mm/mremap.c
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -47,7 +47,8 @@ static pmd_t *get_old_pmd(struct mm_stru
 	return pmd;
 }
 
-static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr)
+static pmd_t *alloc_new_pmd(struct mm_struct *mm, struct vm_area_struct *vma,
+			    unsigned long addr)
 {
 	pgd_t *pgd;
 	pud_t *pud;
@@ -62,7 +63,7 @@ static pmd_t *alloc_new_pmd(struct mm_st
 	if (!pmd)
 		return NULL;
 
-	if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr))
+	if (!pmd_present(*pmd) && __pte_alloc(mm, vma, pmd, addr))
 		return NULL;
 
 	return pmd;
@@ -147,7 +148,7 @@ unsigned long move_page_tables(struct vm
 		old_pmd = get_old_pmd(vma->vm_mm, old_addr);
 		if (!old_pmd)
 			continue;
-		new_pmd = alloc_new_pmd(vma->vm_mm, new_addr);
+		new_pmd = alloc_new_pmd(vma->vm_mm, vma, new_addr);
 		if (!new_pmd)
 			break;
 		next = (new_addr + PMD_SIZE) & PMD_MASK;

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[PATCH 18 of 67] add pmd mmu_notifier helpers

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Add mmu notifier helpers to handle pmd huge operations.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -243,6 +243,32 @@ static inline void mmu_notifier_mm_destr
 	__pte;								\
 })
 
+#define pmdp_clear_flush_notify(__vma, __address, __pmdp)		\
+({									\
+	pmd_t __pmd;							\
+	struct vm_area_struct *___vma = __vma;				\
+	unsigned long ___address = __address;				\
+	VM_BUG_ON(__address & ~HPAGE_PMD_MASK);				\
+	mmu_notifier_invalidate_range_start(___vma->vm_mm, ___address,	\
+					    (__address)+HPAGE_PMD_SIZE);\
+	__pmd = pmdp_clear_flush(___vma, ___address, __pmdp);		\
+	mmu_notifier_invalidate_range_end(___vma->vm_mm, ___address,	\
+					  (__address)+HPAGE_PMD_SIZE);	\
+	__pmd;								\
+})
+
+#define pmdp_splitting_flush_notify(__vma, __address, __pmdp)		\
+({									\
+	struct vm_area_struct *___vma = __vma;				\
+	unsigned long ___address = __address;				\
+	VM_BUG_ON(__address & ~HPAGE_PMD_MASK);				\
+	mmu_notifier_invalidate_range_start(___vma->vm_mm, ___address,	\
+					    (__address)+HPAGE_PMD_SIZE);\
+	pmdp_splitting_flush(___vma, ___address, __pmdp);		\
+	mmu_notifier_invalidate_range_end(___vma->vm_mm, ___address,	\
+					  (__address)+HPAGE_PMD_SIZE);	\
+})
+
 #define ptep_clear_flush_young_notify(__vma, __address, __ptep)		\
 ({									\
 	int __young;							\
@@ -254,6 +280,17 @@ static inline void mmu_notifier_mm_destr
 	__young;							\
 })
 
+#define pmdp_clear_flush_young_notify(__vma, __address, __pmdp)		\
+({									\
+	int __young;							\
+	struct vm_area_struct *___vma = __vma;				\
+	unsigned long ___address = __address;				\
+	__young = pmdp_clear_flush_young(___vma, ___address, __pmdp);	\
+	__young |= mmu_notifier_clear_flush_young(___vma->vm_mm,	\
+						  ___address);		\
+	__young;							\
+})
+
 #define set_pte_at_notify(__mm, __address, __ptep, __pte)		\
 ({									\
 	struct mm_struct *___mm = __mm;					\
@@ -305,7 +342,10 @@ static inline void mmu_notifier_mm_destr
 }
 
 #define ptep_clear_flush_young_notify ptep_clear_flush_young
+#define pmdp_clear_flush_young_notify pmdp_clear_flush_young
 #define ptep_clear_flush_notify ptep_clear_flush
+#define pmdp_clear_flush_notify pmdp_clear_flush
+#define pmdp_splitting_flush_notify pmdp_splitting_flush
 #define set_pte_at_notify set_pte_at
 
 #endif /* CONFIG_MMU_NOTIFIER */

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[PATCH 19 of 67] clear page compound

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

split_huge_page must transform a compound page to a regular page and needs
ClearPageCompound.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
---

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -349,7 +349,7 @@ static inline void set_page_writeback(st
  * tests can be used in performance sensitive paths. PageCompound is
  * generally not used in hot code paths.
  */
-__PAGEFLAG(Head, head)
+__PAGEFLAG(Head, head) CLEARPAGEFLAG(Head, head)
 __PAGEFLAG(Tail, tail)
 
 static inline int PageCompound(struct page *page)
@@ -357,6 +357,13 @@ static inline int PageCompound(struct pa
 	return page->flags & ((1L << PG_head) | (1L << PG_tail));
 
 }
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline void ClearPageCompound(struct page *page)
+{
+	BUG_ON(!PageHead(page));
+	ClearPageHead(page);
+}
+#endif
 #else
 /*
  * Reduce page flag use as much as possible by overlapping
@@ -394,6 +401,14 @@ static inline void __ClearPageTail(struc
 	page->flags &= ~PG_head_tail_mask;
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline void ClearPageCompound(struct page *page)
+{
+	BUG_ON((page->flags & PG_head_tail_mask) != (1 << PG_compound));
+	clear_bit(PG_compound, &page->flags);
+}
+#endif
+
 #endif /* !PAGEFLAGS_EXTENDED */
 
 #ifdef CONFIG_MMU

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[PATCH 20 of 67] add pmd_huge_pte to mm_struct

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

This increase the size of the mm struct a bit but it is needed to preallocate
one pte for each hugepage so that split_huge_page will not require a fail path.
Guarantee of success is a fundamental property of split_huge_page to avoid
decrasing swapping reliability and to avoid adding -ENOMEM fail paths that
would otherwise force the hugepage-unaware VM code to learn rolling back in the
middle of its pte mangling operations (if something we need it to learn
handling pmd_trans_huge natively rather being capable of rollback). When
split_huge_page runs a pte is needed to succeed the split, to map the newly
splitted regular pages with a regular pte.  This way all existing VM code
remains backwards compatible by just adding a split_huge_page* one liner. The
memory waste of those preallocated ptes is negligible and so it is worth it.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -310,6 +310,9 @@ struct mm_struct {
 #ifdef CONFIG_MMU_NOTIFIER
 	struct mmu_notifier_mm *mmu_notifier_mm;
 #endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	pgtable_t pmd_huge_pte; /* protected by page_table_lock */
+#endif
 };
 
 /* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
diff --git a/kernel/fork.c b/kernel/fork.c
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -509,6 +509,9 @@ void __mmdrop(struct mm_struct *mm)
 	mm_free_pgd(mm);
 	destroy_context(mm);
 	mmu_notifier_mm_destroy(mm);
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	VM_BUG_ON(mm->pmd_huge_pte);
+#endif
 	free_mm(mm);
 }
 EXPORT_SYMBOL_GPL(__mmdrop);
@@ -649,6 +652,10 @@ struct mm_struct *dup_mm(struct task_str
 	mm->token_priority = 0;
 	mm->last_interval = 0;
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	mm->pmd_huge_pte = NULL;
+#endif
+
 	if (!mm_init(mm, tsk))
 		goto fail_nomem;
 

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[PATCH 21 of 67] This fixes some minor issues that bugged me while going over the code:

[Andrea Arcangeli]

o adjust argument order of do_mincore() to match the syscall
o simplify range length calculation
o drop superfluous shift in huge tlb calculation, address is page aligned
o drop dead nr_huge calculation
o check pte_none() before pte_present()
o comment and whitespace fixes

No semantic changes intended.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/mincore.c b/mm/mincore.c
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -54,7 +54,7 @@ static unsigned char mincore_page(struct
  * all the arguments, we hold the mmap semaphore: we should
  * just return the amount of info we're asked for.
  */
-static long do_mincore(unsigned long addr, unsigned char *vec, unsigned long pages)
+static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)
 {
 	pgd_t *pgd;
 	pud_t *pud;
@@ -64,35 +64,29 @@ static long do_mincore(unsigned long add
 	unsigned long nr;
 	int i;
 	pgoff_t pgoff;
-	struct vm_area_struct *vma = find_vma(current->mm, addr);
+	struct vm_area_struct *vma;
 
-	/*
-	 * find_vma() didn't find anything above us, or we're
-	 * in an unmapped hole in the address space: ENOMEM.
-	 */
+	vma = find_vma(current->mm, addr);
 	if (!vma || addr < vma->vm_start)
 		return -ENOMEM;
 
+	nr = min(pages, (vma->vm_end - addr) >> PAGE_SHIFT);
+
 #ifdef CONFIG_HUGETLB_PAGE
 	if (is_vm_hugetlb_page(vma)) {
 		struct hstate *h;
-		unsigned long nr_huge;
-		unsigned char present;
 
 		i = 0;
-		nr = min(pages, (vma->vm_end - addr) >> PAGE_SHIFT);
 		h = hstate_vma(vma);
-		nr_huge = ((addr + pages * PAGE_SIZE - 1) >> huge_page_shift(h))
-			  - (addr >> huge_page_shift(h)) + 1;
-		nr_huge = min(nr_huge,
-			      (vma->vm_end - addr) >> huge_page_shift(h));
 		while (1) {
-			/* hugepage always in RAM for now,
-			 * but generally it needs to be check */
+			unsigned char present;
+			/*
+			 * Huge pages are always in RAM for now, but
+			 * theoretically it needs to be checked.
+			 */
 			ptep = huge_pte_offset(current->mm,
 					       addr & huge_page_mask(h));
-			present = !!(ptep &&
-				     !huge_pte_none(huge_ptep_get(ptep)));
+			present = ptep && !huge_pte_none(huge_ptep_get(ptep));
 			while (1) {
 				vec[i++] = present;
 				addr += PAGE_SIZE;
@@ -100,8 +94,7 @@ static long do_mincore(unsigned long add
 				if (i == nr)
 					return nr;
 				/* check hugepage border */
-				if (!((addr & ~huge_page_mask(h))
-				      >> PAGE_SHIFT))
+				if (!(addr & ~huge_page_mask(h)))
 					break;
 			}
 		}
@@ -113,17 +106,7 @@ static long do_mincore(unsigned long add
 	 * Calculate how many pages there are left in the last level of the
 	 * PTE array for our address.
 	 */
-	nr = PTRS_PER_PTE - ((addr >> PAGE_SHIFT) & (PTRS_PER_PTE-1));
-
-	/*
-	 * Don't overrun this vma
-	 */
-	nr = min(nr, (vma->vm_end - addr) >> PAGE_SHIFT);
-
-	/*
-	 * Don't return more than the caller asked for
-	 */
-	nr = min(nr, pages);
+	nr = min(nr, PTRS_PER_PTE - ((addr >> PAGE_SHIFT) & (PTRS_PER_PTE-1)));
 
 	pgd = pgd_offset(vma->vm_mm, addr);
 	if (pgd_none_or_clear_bad(pgd))
@@ -137,43 +120,38 @@ static long do_mincore(unsigned long add
 
 	ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
 	for (i = 0; i < nr; i++, ptep++, addr += PAGE_SIZE) {
-		unsigned char present;
 		pte_t pte = *ptep;
 
-		if (pte_present(pte)) {
-			present = 1;
-
-		} else if (pte_none(pte)) {
+		if (pte_none(pte)) {
 			if (vma->vm_file) {
 				pgoff = linear_page_index(vma, addr);
-				present = mincore_page(vma->vm_file->f_mapping,
-							pgoff);
+				vec[i] = mincore_page(vma->vm_file->f_mapping,
+						pgoff);
 			} else
-				present = 0;
-
-		} else if (pte_file(pte)) {
+				vec[i] = 0;
+		} else if (pte_present(pte))
+			vec[i] = 1;
+		else if (pte_file(pte)) {
 			pgoff = pte_to_pgoff(pte);
-			present = mincore_page(vma->vm_file->f_mapping, pgoff);
-
+			vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
 		} else { /* pte is a swap entry */
 			swp_entry_t entry = pte_to_swp_entry(pte);
+
 			if (is_migration_entry(entry)) {
 				/* migration entries are always uptodate */
-				present = 1;
+				vec[i] = 1;
 			} else {
 #ifdef CONFIG_SWAP
 				pgoff = entry.val;
-				present = mincore_page(&swapper_space, pgoff);
+				vec[i] = mincore_page(&swapper_space, pgoff);
 #else
 				WARN_ON(1);
-				present = 1;
+				vec[i] = 1;
 #endif
 			}
 		}
-
-		vec[i] = present;
 	}
-	pte_unmap_unlock(ptep-1, ptl);
+	pte_unmap_unlock(ptep - 1, ptl);
 
 	return nr;
 
@@ -247,7 +225,7 @@ SYSCALL_DEFINE3(mincore, unsigned long, 
 		 * the temporary buffer size.
 		 */
 		down_read(&current->mm->mmap_sem);
-		retval = do_mincore(start, tmp, min(pages, PAGE_SIZE));
+		retval = do_mincore(start, min(pages, PAGE_SIZE), tmp);
 		up_read(&current->mm->mmap_sem);
 
 		if (retval <= 0)

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[PATCH 22 of 67] Split out functions to handle hugetlb ranges, pte ranges and unmapped

[Andrea Arcangeli]

ranges, to improve readability but also to prepare the file structure for
nested page table walks.

No semantic changes intended.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/mincore.c b/mm/mincore.c
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -19,6 +19,42 @@
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 
+static void mincore_hugetlb_page_range(struct vm_area_struct *vma,
+				unsigned long addr, unsigned long nr,
+				unsigned char *vec)
+{
+#ifdef CONFIG_HUGETLB_PAGE
+	struct hstate *h;
+	int i;
+
+	i = 0;
+	h = hstate_vma(vma);
+	while (1) {
+		unsigned char present;
+		pte_t *ptep;
+		/*
+		 * Huge pages are always in RAM for now, but
+		 * theoretically it needs to be checked.
+		 */
+		ptep = huge_pte_offset(current->mm,
+				       addr & huge_page_mask(h));
+		present = ptep && !huge_pte_none(huge_ptep_get(ptep));
+		while (1) {
+			vec[i++] = present;
+			addr += PAGE_SIZE;
+			/* reach buffer limit */
+			if (i == nr)
+				return;
+			/* check hugepage border */
+			if (!(addr & ~huge_page_mask(h)))
+				break;
+		}
+	}
+#else
+	BUG();
+#endif
+}
+
 /*
  * Later we can get more picky about what "in core" means precisely.
  * For now, simply check to see if the page is in the page cache,
@@ -49,87 +85,40 @@ static unsigned char mincore_page(struct
 	return present;
 }
 
-/*
- * Do a chunk of "sys_mincore()". We've already checked
- * all the arguments, we hold the mmap semaphore: we should
- * just return the amount of info we're asked for.
- */
-static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)
+static void mincore_unmapped_range(struct vm_area_struct *vma,
+				unsigned long addr, unsigned long nr,
+				unsigned char *vec)
 {
-	pgd_t *pgd;
-	pud_t *pud;
-	pmd_t *pmd;
+	int i;
+
+	if (vma->vm_file) {
+		pgoff_t pgoff;
+
+		pgoff = linear_page_index(vma, addr);
+		for (i = 0; i < nr; i++, pgoff++)
+			vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
+	} else {
+		for (i = 0; i < nr; i++)
+			vec[i] = 0;
+	}
+}
+
+static void mincore_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
+			unsigned long addr, unsigned long nr,
+			unsigned char *vec)
+{
+	spinlock_t *ptl;
 	pte_t *ptep;
-	spinlock_t *ptl;
-	unsigned long nr;
 	int i;
-	pgoff_t pgoff;
-	struct vm_area_struct *vma;
-
-	vma = find_vma(current->mm, addr);
-	if (!vma || addr < vma->vm_start)
-		return -ENOMEM;
-
-	nr = min(pages, (vma->vm_end - addr) >> PAGE_SHIFT);
-
-#ifdef CONFIG_HUGETLB_PAGE
-	if (is_vm_hugetlb_page(vma)) {
-		struct hstate *h;
-
-		i = 0;
-		h = hstate_vma(vma);
-		while (1) {
-			unsigned char present;
-			/*
-			 * Huge pages are always in RAM for now, but
-			 * theoretically it needs to be checked.
-			 */
-			ptep = huge_pte_offset(current->mm,
-					       addr & huge_page_mask(h));
-			present = ptep && !huge_pte_none(huge_ptep_get(ptep));
-			while (1) {
-				vec[i++] = present;
-				addr += PAGE_SIZE;
-				/* reach buffer limit */
-				if (i == nr)
-					return nr;
-				/* check hugepage border */
-				if (!(addr & ~huge_page_mask(h)))
-					break;
-			}
-		}
-		return nr;
-	}
-#endif
-
-	/*
-	 * Calculate how many pages there are left in the last level of the
-	 * PTE array for our address.
-	 */
-	nr = min(nr, PTRS_PER_PTE - ((addr >> PAGE_SHIFT) & (PTRS_PER_PTE-1)));
-
-	pgd = pgd_offset(vma->vm_mm, addr);
-	if (pgd_none_or_clear_bad(pgd))
-		goto none_mapped;
-	pud = pud_offset(pgd, addr);
-	if (pud_none_or_clear_bad(pud))
-		goto none_mapped;
-	pmd = pmd_offset(pud, addr);
-	if (pmd_none_or_clear_bad(pmd))
-		goto none_mapped;
 
 	ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
 	for (i = 0; i < nr; i++, ptep++, addr += PAGE_SIZE) {
 		pte_t pte = *ptep;
+		pgoff_t pgoff;
 
-		if (pte_none(pte)) {
-			if (vma->vm_file) {
-				pgoff = linear_page_index(vma, addr);
-				vec[i] = mincore_page(vma->vm_file->f_mapping,
-						pgoff);
-			} else
-				vec[i] = 0;
-		} else if (pte_present(pte))
+		if (pte_none(pte))
+			mincore_unmapped_range(vma, addr, 1, vec);
+		else if (pte_present(pte))
 			vec[i] = 1;
 		else if (pte_file(pte)) {
 			pgoff = pte_to_pgoff(pte);
@@ -152,19 +141,53 @@ static long do_mincore(unsigned long add
 		}
 	}
 	pte_unmap_unlock(ptep - 1, ptl);
+}
 
+/*
+ * Do a chunk of "sys_mincore()". We've already checked
+ * all the arguments, we hold the mmap semaphore: we should
+ * just return the amount of info we're asked for.
+ */
+static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	unsigned long nr;
+	struct vm_area_struct *vma;
+
+	vma = find_vma(current->mm, addr);
+	if (!vma || addr < vma->vm_start)
+		return -ENOMEM;
+
+	nr = min(pages, (vma->vm_end - addr) >> PAGE_SHIFT);
+
+	if (is_vm_hugetlb_page(vma)) {
+		mincore_hugetlb_page_range(vma, addr, nr, vec);
+		return nr;
+	}
+
+	/*
+	 * Calculate how many pages there are left in the last level of the
+	 * PTE array for our address.
+	 */
+	nr = min(nr, PTRS_PER_PTE - ((addr >> PAGE_SHIFT) & (PTRS_PER_PTE-1)));
+
+	pgd = pgd_offset(vma->vm_mm, addr);
+	if (pgd_none_or_clear_bad(pgd))
+		goto none_mapped;
+	pud = pud_offset(pgd, addr);
+	if (pud_none_or_clear_bad(pud))
+		goto none_mapped;
+	pmd = pmd_offset(pud, addr);
+	if (pmd_none_or_clear_bad(pmd))
+		goto none_mapped;
+
+	mincore_pte_range(vma, pmd, addr, nr, vec);
 	return nr;
 
 none_mapped:
-	if (vma->vm_file) {
-		pgoff = linear_page_index(vma, addr);
-		for (i = 0; i < nr; i++, pgoff++)
-			vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
-	} else {
-		for (i = 0; i < nr; i++)
-			vec[i] = 0;
-	}
-
+	mincore_unmapped_range(vma, addr, nr, vec);
 	return nr;
 }
 

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[PATCH 23 of 67] Instead of passing a start address and a number of pages into the helper

[Andrea Arcangeli]

functions, convert them to use a start and an end address.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/mincore.c b/mm/mincore.c
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -20,14 +20,12 @@
 #include <asm/pgtable.h>
 
 static void mincore_hugetlb_page_range(struct vm_area_struct *vma,
-				unsigned long addr, unsigned long nr,
+				unsigned long addr, unsigned long end,
 				unsigned char *vec)
 {
 #ifdef CONFIG_HUGETLB_PAGE
 	struct hstate *h;
-	int i;
 
-	i = 0;
 	h = hstate_vma(vma);
 	while (1) {
 		unsigned char present;
@@ -40,10 +38,10 @@ static void mincore_hugetlb_page_range(s
 				       addr & huge_page_mask(h));
 		present = ptep && !huge_pte_none(huge_ptep_get(ptep));
 		while (1) {
-			vec[i++] = present;
+			*vec = present;
+			vec++;
 			addr += PAGE_SIZE;
-			/* reach buffer limit */
-			if (i == nr)
+			if (addr == end)
 				return;
 			/* check hugepage border */
 			if (!(addr & ~huge_page_mask(h)))
@@ -86,9 +84,10 @@ static unsigned char mincore_page(struct
 }
 
 static void mincore_unmapped_range(struct vm_area_struct *vma,
-				unsigned long addr, unsigned long nr,
+				unsigned long addr, unsigned long end,
 				unsigned char *vec)
 {
+	unsigned long nr = (end - addr) >> PAGE_SHIFT;
 	int i;
 
 	if (vma->vm_file) {
@@ -104,42 +103,44 @@ static void mincore_unmapped_range(struc
 }
 
 static void mincore_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
-			unsigned long addr, unsigned long nr,
+			unsigned long addr, unsigned long end,
 			unsigned char *vec)
 {
+	unsigned long next;
 	spinlock_t *ptl;
 	pte_t *ptep;
-	int i;
 
 	ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
-	for (i = 0; i < nr; i++, ptep++, addr += PAGE_SIZE) {
+	do {
 		pte_t pte = *ptep;
 		pgoff_t pgoff;
 
+		next = addr + PAGE_SIZE;
 		if (pte_none(pte))
-			mincore_unmapped_range(vma, addr, 1, vec);
+			mincore_unmapped_range(vma, addr, next, vec);
 		else if (pte_present(pte))
-			vec[i] = 1;
+			*vec = 1;
 		else if (pte_file(pte)) {
 			pgoff = pte_to_pgoff(pte);
-			vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
+			*vec = mincore_page(vma->vm_file->f_mapping, pgoff);
 		} else { /* pte is a swap entry */
 			swp_entry_t entry = pte_to_swp_entry(pte);
 
 			if (is_migration_entry(entry)) {
 				/* migration entries are always uptodate */
-				vec[i] = 1;
+				*vec = 1;
 			} else {
 #ifdef CONFIG_SWAP
 				pgoff = entry.val;
-				vec[i] = mincore_page(&swapper_space, pgoff);
+				*vec = mincore_page(&swapper_space, pgoff);
 #else
 				WARN_ON(1);
-				vec[i] = 1;
+				*vec = 1;
 #endif
 			}
 		}
-	}
+		vec++;
+	} while (ptep++, addr = next, addr != end);
 	pte_unmap_unlock(ptep - 1, ptl);
 }
 
@@ -153,25 +154,21 @@ static long do_mincore(unsigned long add
 	pgd_t *pgd;
 	pud_t *pud;
 	pmd_t *pmd;
-	unsigned long nr;
 	struct vm_area_struct *vma;
+	unsigned long end;
 
 	vma = find_vma(current->mm, addr);
 	if (!vma || addr < vma->vm_start)
 		return -ENOMEM;
 
-	nr = min(pages, (vma->vm_end - addr) >> PAGE_SHIFT);
+	end = min(vma->vm_end, addr + (pages << PAGE_SHIFT));
 
 	if (is_vm_hugetlb_page(vma)) {
-		mincore_hugetlb_page_range(vma, addr, nr, vec);
-		return nr;
+		mincore_hugetlb_page_range(vma, addr, end, vec);
+		return (end - addr) >> PAGE_SHIFT;
 	}
 
-	/*
-	 * Calculate how many pages there are left in the last level of the
-	 * PTE array for our address.
-	 */
-	nr = min(nr, PTRS_PER_PTE - ((addr >> PAGE_SHIFT) & (PTRS_PER_PTE-1)));
+	end = pmd_addr_end(addr, end);
 
 	pgd = pgd_offset(vma->vm_mm, addr);
 	if (pgd_none_or_clear_bad(pgd))
@@ -183,12 +180,12 @@ static long do_mincore(unsigned long add
 	if (pmd_none_or_clear_bad(pmd))
 		goto none_mapped;
 
-	mincore_pte_range(vma, pmd, addr, nr, vec);
-	return nr;
+	mincore_pte_range(vma, pmd, addr, end, vec);
+	return (end - addr) >> PAGE_SHIFT;
 
 none_mapped:
-	mincore_unmapped_range(vma, addr, nr, vec);
-	return nr;
+	mincore_unmapped_range(vma, addr, end, vec);
+	return (end - addr) >> PAGE_SHIFT;
 }
 
 /*

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[PATCH 24 of 67] Do page table walks with the well-known nested loops we use in several

[Andrea Arcangeli]

other places already.

This avoids doing full page table walks after every pte range and also
allows to handle unmapped areas bigger than one pte range in one go.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/mincore.c b/mm/mincore.c
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -144,6 +144,60 @@ static void mincore_pte_range(struct vm_
 	pte_unmap_unlock(ptep - 1, ptl);
 }
 
+static void mincore_pmd_range(struct vm_area_struct *vma, pud_t *pud,
+			unsigned long addr, unsigned long end,
+			unsigned char *vec)
+{
+	unsigned long next;
+	pmd_t *pmd;
+
+	pmd = pmd_offset(pud, addr);
+	do {
+		next = pmd_addr_end(addr, end);
+		if (pmd_none_or_clear_bad(pmd))
+			mincore_unmapped_range(vma, addr, next, vec);
+		else
+			mincore_pte_range(vma, pmd, addr, next, vec);
+		vec += (next - addr) >> PAGE_SHIFT;
+	} while (pmd++, addr = next, addr != end);
+}
+
+static void mincore_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
+			unsigned long addr, unsigned long end,
+			unsigned char *vec)
+{
+	unsigned long next;
+	pud_t *pud;
+
+	pud = pud_offset(pgd, addr);
+	do {
+		next = pud_addr_end(addr, end);
+		if (pud_none_or_clear_bad(pud))
+			mincore_unmapped_range(vma, addr, next, vec);
+		else
+			mincore_pmd_range(vma, pud, addr, next, vec);
+		vec += (next - addr) >> PAGE_SHIFT;
+	} while (pud++, addr = next, addr != end);
+}
+
+static void mincore_page_range(struct vm_area_struct *vma,
+			unsigned long addr, unsigned long end,
+			unsigned char *vec)
+{
+	unsigned long next;
+	pgd_t *pgd;
+
+	pgd = pgd_offset(vma->vm_mm, addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		if (pgd_none_or_clear_bad(pgd))
+			mincore_unmapped_range(vma, addr, next, vec);
+		else
+			mincore_pud_range(vma, pgd, addr, next, vec);
+		vec += (next - addr) >> PAGE_SHIFT;
+	} while (pgd++, addr = next, addr != end);
+}
+
 /*
  * Do a chunk of "sys_mincore()". We've already checked
  * all the arguments, we hold the mmap semaphore: we should
@@ -151,9 +205,6 @@ static void mincore_pte_range(struct vm_
  */
 static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)
 {
-	pgd_t *pgd;
-	pud_t *pud;
-	pmd_t *pmd;
 	struct vm_area_struct *vma;
 	unsigned long end;
 
@@ -170,21 +221,11 @@ static long do_mincore(unsigned long add
 
 	end = pmd_addr_end(addr, end);
 
-	pgd = pgd_offset(vma->vm_mm, addr);
-	if (pgd_none_or_clear_bad(pgd))
-		goto none_mapped;
-	pud = pud_offset(pgd, addr);
-	if (pud_none_or_clear_bad(pud))
-		goto none_mapped;
-	pmd = pmd_offset(pud, addr);
-	if (pmd_none_or_clear_bad(pmd))
-		goto none_mapped;
+	if (is_vm_hugetlb_page(vma))
+		mincore_hugetlb_page_range(vma, addr, end, vec);
+	else
+		mincore_page_range(vma, addr, end, vec);
 
-	mincore_pte_range(vma, pmd, addr, end, vec);
-	return (end - addr) >> PAGE_SHIFT;
-
-none_mapped:
-	mincore_unmapped_range(vma, addr, end, vec);
 	return (end - addr) >> PAGE_SHIFT;
 }
 

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[PATCH 25 of 67] split_huge_page_mm/vma

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

split_huge_page_pmd compat code. Each one of those would need to be expanded to
hundred of lines of complex code without a fully reliable
split_huge_page_pmd design.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---

diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -179,6 +179,7 @@ static void mark_screen_rdonly(struct mm
 	if (pud_none_or_clear_bad(pud))
 		goto out;
 	pmd = pmd_offset(pud, 0xA0000);
+	split_huge_page_pmd(mm, pmd);
 	if (pmd_none_or_clear_bad(pmd))
 		goto out;
 	pte = pte_offset_map_lock(mm, pmd, 0xA0000, &ptl);
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -445,6 +445,7 @@ static inline int check_pmd_range(struct
 	pmd = pmd_offset(pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
+		split_huge_page_pmd(vma->vm_mm, pmd);
 		if (pmd_none_or_clear_bad(pmd))
 			continue;
 		if (check_pte_range(vma, pmd, addr, next, nodes,
diff --git a/mm/mincore.c b/mm/mincore.c
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -154,6 +154,7 @@ static void mincore_pmd_range(struct vm_
 	pmd = pmd_offset(pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
+		split_huge_page_pmd(vma->vm_mm, pmd);
 		if (pmd_none_or_clear_bad(pmd))
 			mincore_unmapped_range(vma, addr, next, vec);
 		else
diff --git a/mm/mprotect.c b/mm/mprotect.c
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -88,6 +88,7 @@ static inline void change_pmd_range(stru
 	pmd = pmd_offset(pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
+		split_huge_page_pmd(mm, pmd);
 		if (pmd_none_or_clear_bad(pmd))
 			continue;
 		change_pte_range(mm, pmd, addr, next, newprot, dirty_accountable);
diff --git a/mm/mremap.c b/mm/mremap.c
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -41,6 +41,7 @@ static pmd_t *get_old_pmd(struct mm_stru
 		return NULL;
 
 	pmd = pmd_offset(pud, addr);
+	split_huge_page_pmd(mm, pmd);
 	if (pmd_none_or_clear_bad(pmd))
 		return NULL;
 
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -34,6 +34,7 @@ static int walk_pmd_range(pud_t *pud, un
 	pmd = pmd_offset(pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
+		split_huge_page_pmd(walk->mm, pmd);
 		if (pmd_none_or_clear_bad(pmd)) {
 			if (walk->pte_hole)
 				err = walk->pte_hole(addr, next, walk);

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[PATCH 26 of 67] split_huge_page paging

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Paging logic that splits the page before it is unmapped and added to swap to
ensure backwards compatibility with the legacy swap code. Eventually swap
should natively pageout the hugepages to increase performance and decrease
seeking and fragmentation of swap space. swapoff can just skip over huge pmd as
they cannot be part of swap yet. In add_to_swap be careful to split the page
only if we got a valid swap entry so we don't split hugepages with a full swap.

In theory we could split pages before isolating them during the lru scan, but
for khugepaged to be safe, I'm relying on either mmap_sem write mode, or
PG_lock taken, so split_huge_page has to run either with mmap_sem read/write
mode or PG_lock taken. Calling it from isolate_lru_page would make locking more
complicated, in addition to that split_huge_page would deadlock if called by
__isolate_lru_page because it has to take the lru lock to add the tail pages.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -379,6 +379,8 @@ static void collect_procs_anon(struct pa
 	struct task_struct *tsk;
 	struct anon_vma *av;
 
+	if (unlikely(split_huge_page(page)))
+		return;
 	read_lock(&tasklist_lock);
 	av = page_lock_anon_vma(page);
 	if (av == NULL)	/* Not actually mapped anymore */
diff --git a/mm/rmap.c b/mm/rmap.c
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1285,6 +1285,7 @@ int try_to_unmap(struct page *page, enum
 	int ret;
 
 	BUG_ON(!PageLocked(page));
+	BUG_ON(PageTransHuge(page));
 
 	if (unlikely(PageKsm(page)))
 		ret = try_to_unmap_ksm(page, flags);
diff --git a/mm/swap_state.c b/mm/swap_state.c
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -157,6 +157,12 @@ int add_to_swap(struct page *page)
 	if (!entry.val)
 		return 0;
 
+	if (unlikely(PageTransHuge(page)))
+		if (unlikely(split_huge_page(page))) {
+			swapcache_free(entry, NULL);
+			return 0;
+		}
+
 	/*
 	 * Radix-tree node allocations from PF_MEMALLOC contexts could
 	 * completely exhaust the page allocator. __GFP_NOMEMALLOC
diff --git a/mm/swapfile.c b/mm/swapfile.c
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -937,6 +937,8 @@ static inline int unuse_pmd_range(struct
 	pmd = pmd_offset(pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
+		if (unlikely(pmd_trans_huge(*pmd)))
+			continue;
 		if (pmd_none_or_clear_bad(pmd))
 			continue;
 		ret = unuse_pte_range(vma, pmd, addr, next, entry, page);

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[PATCH 27 of 67] clear_copy_huge_page

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Move the copy/clear_huge_page functions to common code to share between
hugetlb.c and huge_memory.c.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
---

diff --git a/include/linux/mm.h b/include/linux/mm.h
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1506,5 +1506,14 @@ extern int soft_offline_page(struct page
 
 extern void dump_page(struct page *page);
 
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
+extern void clear_huge_page(struct page *page,
+			    unsigned long addr,
+			    unsigned int pages_per_huge_page);
+extern void copy_huge_page(struct page *dst, struct page *src,
+			   unsigned long addr, struct vm_area_struct *vma,
+			   unsigned int pages_per_huge_page);
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_MM_H */
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -385,70 +385,6 @@ static int vma_has_reserves(struct vm_ar
 	return 0;
 }
 
-static void clear_gigantic_page(struct page *page,
-			unsigned long addr, unsigned long sz)
-{
-	int i;
-	struct page *p = page;
-
-	might_sleep();
-	for (i = 0; i < sz/PAGE_SIZE; i++, p = mem_map_next(p, page, i)) {
-		cond_resched();
-		clear_user_highpage(p, addr + i * PAGE_SIZE);
-	}
-}
-static void clear_huge_page(struct page *page,
-			unsigned long addr, unsigned long sz)
-{
-	int i;
-
-	if (unlikely(sz/PAGE_SIZE > MAX_ORDER_NR_PAGES)) {
-		clear_gigantic_page(page, addr, sz);
-		return;
-	}
-
-	might_sleep();
-	for (i = 0; i < sz/PAGE_SIZE; i++) {
-		cond_resched();
-		clear_user_highpage(page + i, addr + i * PAGE_SIZE);
-	}
-}
-
-static void copy_gigantic_page(struct page *dst, struct page *src,
-			   unsigned long addr, struct vm_area_struct *vma)
-{
-	int i;
-	struct hstate *h = hstate_vma(vma);
-	struct page *dst_base = dst;
-	struct page *src_base = src;
-	might_sleep();
-	for (i = 0; i < pages_per_huge_page(h); ) {
-		cond_resched();
-		copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
-
-		i++;
-		dst = mem_map_next(dst, dst_base, i);
-		src = mem_map_next(src, src_base, i);
-	}
-}
-static void copy_huge_page(struct page *dst, struct page *src,
-			   unsigned long addr, struct vm_area_struct *vma)
-{
-	int i;
-	struct hstate *h = hstate_vma(vma);
-
-	if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) {
-		copy_gigantic_page(dst, src, addr, vma);
-		return;
-	}
-
-	might_sleep();
-	for (i = 0; i < pages_per_huge_page(h); i++) {
-		cond_resched();
-		copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
-	}
-}
-
 static void enqueue_huge_page(struct hstate *h, struct page *page)
 {
 	int nid = page_to_nid(page);
@@ -2333,7 +2269,8 @@ retry_avoidcopy:
 		return -PTR_ERR(new_page);
 	}
 
-	copy_huge_page(new_page, old_page, address, vma);
+	copy_huge_page(new_page, old_page, address, vma,
+		       pages_per_huge_page(h));
 	__SetPageUptodate(new_page);
 
 	/*
@@ -2429,7 +2366,7 @@ retry:
 			ret = -PTR_ERR(page);
 			goto out;
 		}
-		clear_huge_page(page, address, huge_page_size(h));
+		clear_huge_page(page, address, pages_per_huge_page(h));
 		__SetPageUptodate(page);
 
 		if (vma->vm_flags & VM_MAYSHARE) {
diff --git a/mm/memory.c b/mm/memory.c
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3495,3 +3495,73 @@ void might_fault(void)
 }
 EXPORT_SYMBOL(might_fault);
 #endif
+
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
+static void clear_gigantic_page(struct page *page,
+				unsigned long addr,
+				unsigned int pages_per_huge_page)
+{
+	int i;
+	struct page *p = page;
+
+	might_sleep();
+	for (i = 0; i < pages_per_huge_page;
+	     i++, p = mem_map_next(p, page, i)) {
+		cond_resched();
+		clear_user_highpage(p, addr + i * PAGE_SIZE);
+	}
+}
+void clear_huge_page(struct page *page,
+		     unsigned long addr, unsigned int pages_per_huge_page)
+{
+	int i;
+
+	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
+		clear_gigantic_page(page, addr, pages_per_huge_page);
+		return;
+	}
+
+	might_sleep();
+	for (i = 0; i < pages_per_huge_page; i++) {
+		cond_resched();
+		clear_user_highpage(page + i, addr + i * PAGE_SIZE);
+	}
+}
+
+static void copy_gigantic_page(struct page *dst, struct page *src,
+			       unsigned long addr,
+			       struct vm_area_struct *vma,
+			       unsigned int pages_per_huge_page)
+{
+	int i;
+	struct page *dst_base = dst;
+	struct page *src_base = src;
+	might_sleep();
+	for (i = 0; i < pages_per_huge_page; ) {
+		cond_resched();
+		copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
+
+		i++;
+		dst = mem_map_next(dst, dst_base, i);
+		src = mem_map_next(src, src_base, i);
+	}
+}
+void copy_huge_page(struct page *dst, struct page *src,
+		    unsigned long addr, struct vm_area_struct *vma,
+		    unsigned int pages_per_huge_page)
+{
+	int i;
+
+	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
+		copy_gigantic_page(dst, src, addr, vma, pages_per_huge_page);
+		return;
+	}
+
+	might_sleep();
+	for (i = 0; i < pages_per_huge_page; i++) {
+		cond_resched();
+		copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE,
+				   vma);
+	}
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */

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[PATCH 28 of 67] kvm mmu transparent hugepage support

[Andrea Arcangeli]

From: Marcelo Tosatti <mtosatti@redhat.com>

This should work for both hugetlbfs and transparent hugepages.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -471,6 +471,15 @@ static int host_mapping_level(struct kvm
 
 	page_size = kvm_host_page_size(kvm, gfn);
 
+	/* check for transparent hugepages */
+	if (page_size == PAGE_SIZE) {
+		struct page *page = gfn_to_page(kvm, gfn);
+
+		if (!is_error_page(page) && PageTransCompound(page))
+			page_size = KVM_HPAGE_SIZE(2);
+		kvm_release_page_clean(page);
+	}
+
 	for (i = PT_PAGE_TABLE_LEVEL;
 	     i < (PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES); ++i) {
 		if (page_size >= KVM_HPAGE_SIZE(i))

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[PATCH 29 of 67] _GFP_NO_KSWAPD

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Transparent hugepage allocations must be allowed not to invoke kswapd or any
other kind of indirect reclaim (especially when the defrag sysfs is control
disabled). It's unacceptable to swap out anonymous pages (potentially
anonymous transparent hugepages) in order to create new transparent hugepages.
This is true for the MADV_HUGEPAGE areas too (swapping out a kvm virtual
machine and so having it suffer an unbearable slowdown, so another one with
guest physical memory marked MADV_HUGEPAGE can run 30% faster if it is running
memory intensive workloads, makes no sense). If a transparent hugepage
allocation fails the slowdown is minor and there is total fallback, so kswapd
should never be asked to swapout memory to allow the high order allocation to
succeed.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -60,13 +60,15 @@ struct vm_area_struct;
 #define __GFP_NOTRACK	((__force gfp_t)0)
 #endif
 
+#define __GFP_NO_KSWAPD	((__force gfp_t)0x400000u)
+
 /*
  * This may seem redundant, but it's a way of annotating false positives vs.
  * allocations that simply cannot be supported (e.g. page tables).
  */
 #define __GFP_NOTRACK_FALSE_POSITIVE (__GFP_NOTRACK)
 
-#define __GFP_BITS_SHIFT 22	/* Room for 22 __GFP_FOO bits */
+#define __GFP_BITS_SHIFT 23	/* Room for 23 __GFP_FOO bits */
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
 
 /* This equals 0, but use constants in case they ever change */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1844,7 +1844,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, u
 		goto nopage;
 
 restart:
-	wake_all_kswapd(order, zonelist, high_zoneidx);
+	if (!(gfp_mask & __GFP_NO_KSWAPD))
+		wake_all_kswapd(order, zonelist, high_zoneidx);
 
 	/*
 	 * OK, we're below the kswapd watermark and have kicked background

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[PATCH 30 of 67] don't alloc harder for gfp nomemalloc even if nowait

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Not worth throwing away the precious reserved free memory pool for allocations
that can fail gracefully (either through mempool or because they're transhuge
allocations later falling back to 4k allocations).

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1788,7 +1788,11 @@ gfp_to_alloc_flags(gfp_t gfp_mask)
 	 */
 	alloc_flags |= (gfp_mask & __GFP_HIGH);
 
-	if (!wait) {
+	/*
+	 * Not worth trying to allocate harder for __GFP_NOMEMALLOC
+	 * even if it can't schedule.
+	 */
+	if (!wait && !(gfp_mask & __GFP_NOMEMALLOC)) {
 		alloc_flags |= ALLOC_HARDER;
 		/*
 		 * Ignore cpuset if GFP_ATOMIC (!wait) rather than fail alloc.

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[PATCH 31 of 67] transparent hugepage core

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Lately I've been working to make KVM use hugepages transparently
without the usual restrictions of hugetlbfs. Some of the restrictions
I'd like to see removed:

1) hugepages have to be swappable or the guest physical memory remains
   locked in RAM and can't be paged out to swap

2) if a hugepage allocation fails, regular pages should be allocated
   instead and mixed in the same vma without any failure and without
   userland noticing

3) if some task quits and more hugepages become available in the
   buddy, guest physical memory backed by regular pages should be
   relocated on hugepages automatically in regions under
   madvise(MADV_HUGEPAGE) (ideally event driven by waking up the
   kernel deamon if the order=HPAGE_PMD_SHIFT-PAGE_SHIFT list becomes
   not null)

4) avoidance of reservation and maximization of use of hugepages whenever
   possible. Reservation (needed to avoid runtime fatal faliures) may be ok for
   1 machine with 1 database with 1 database cache with 1 database cache size
   known at boot time. It's definitely not feasible with a virtualization
   hypervisor usage like RHEV-H that runs an unknown number of virtual machines
   with an unknown size of each virtual machine with an unknown amount of
   pagecache that could be potentially useful in the host for guest not using
   O_DIRECT (aka cache=off).

hugepages in the virtualization hypervisor (and also in the guest!) are
much more important than in a regular host not using virtualization, becasue
with NPT/EPT they decrease the tlb-miss cacheline accesses from 24 to 19 in
case only the hypervisor uses transparent hugepages, and they decrease the
tlb-miss cacheline accesses from 19 to 15 in case both the linux hypervisor and
the linux guest both uses this patch (though the guest will limit the addition
speedup to anonymous regions only for now...).  Even more important is that the
tlb miss handler is much slower on a NPT/EPT guest than for a regular shadow
paging or no-virtualization scenario. So maximizing the amount of virtual
memory cached by the TLB pays off significantly more with NPT/EPT than without
(even if there would be no significant speedup in the tlb-miss runtime).

The first (and more tedious) part of this work requires allowing the VM to
handle anonymous hugepages mixed with regular pages transparently on regular
anonymous vmas. This is what this patch tries to achieve in the least intrusive
possible way. We want hugepages and hugetlb to be used in a way so that all
applications can benefit without changes (as usual we leverage the KVM
virtualization design: by improving the Linux VM at large, KVM gets the
performance boost too).

The most important design choice is: always fallback to 4k allocation
if the hugepage allocation fails! This is the _very_ opposite of some
large pagecache patches that failed with -EIO back then if a 64k (or
similar) allocation failed...

Second important decision (to reduce the impact of the feature on the
existing pagetable handling code) is that at any time we can split an
hugepage into 512 regular pages and it has to be done with an
operation that can't fail. This way the reliability of the swapping
isn't decreased (no need to allocate memory when we are short on
memory to swap) and it's trivial to plug a split_huge_page* one-liner
where needed without polluting the VM. Over time we can teach
mprotect, mremap and friends to handle pmd_trans_huge natively without
calling split_huge_page*. The fact it can't fail isn't just for swap:
if split_huge_page would return -ENOMEM (instead of the current void)
we'd need to rollback the mprotect from the middle of it (ideally
including undoing the split_vma) which would be a big change and in
the very wrong direction (it'd likely be simpler not to call
split_huge_page at all and to teach mprotect and friends to handle
hugepages instead of rolling them back from the middle). In short the
very value of split_huge_page is that it can't fail.

The collapsing and madvise(MADV_HUGEPAGE) part will remain separated
and incremental and it'll just be an "harmless" addition later if this
initial part is agreed upon. It also should be noted that locking-wise
replacing regular pages with hugepages is going to be very easy if
compared to what I'm doing below in split_huge_page, as it will only
happen when page_count(page) matches page_mapcount(page) if we can
take the PG_lock and mmap_sem in write mode. collapse_huge_page will
be a "best effort" that (unlike split_huge_page) can fail at the
minimal sign of trouble and we can try again later. collapse_huge_page
will be similar to how KSM works and the madvise(MADV_HUGEPAGE) will
work similar to madvise(MADV_MERGEABLE).

The default I like is that transparent hugepages are used at page fault time.
This can be changed with /sys/kernel/mm/transparent_hugepage/enabled. The
control knob can be set to three values "always", "madvise", "never" which
mean respectively that hugepages are always used, or only inside
madvise(MADV_HUGEPAGE) regions, or never used.
/sys/kernel/mm/transparent_hugepage/defrag instead controls if the hugepage
allocation should defrag memory aggressively "always", only inside "madvise"
regions, or "never".

The pmd_trans_splitting/pmd_trans_huge locking is very solid. The
put_page (from get_user_page users that can't use mmu notifier like
O_DIRECT) that runs against a __split_huge_page_refcount instead was a
pain to serialize in a way that would result always in a coherent page
count for both tail and head. I think my locking solution with a
compound_lock taken only after the page_first is valid and is still a
PageHead should be safe but it surely needs review from SMP race point
of view. In short there is no current existing way to serialize the
O_DIRECT final put_page against split_huge_page_refcount so I had to
invent a new one (O_DIRECT loses knowledge on the mapping status by
the time gup_fast returns so...). And I didn't want to impact all
gup/gup_fast users for now, maybe if we change the gup interface
substantially we can avoid this locking, I admit I didn't think too
much about it because changing the gup unpinning interface would be
invasive.

If we ignored O_DIRECT we could stick to the existing compound
refcounting code, by simply adding a
get_user_pages_fast_flags(foll_flags) where KVM (and any other mmu
notifier user) would call it without FOLL_GET (and if FOLL_GET isn't
set we'd just BUG_ON if nobody registered itself in the current task
mmu notifier list yet). But O_DIRECT is fundamental for decent
performance of virtualized I/O on fast storage so we can't avoid it to
solve the race of put_page against split_huge_page_refcount to achieve
a complete hugepage feature for KVM.

Swap and oom works fine (well just like with regular pages ;). MMU
notifier is handled transparently too, with the exception of the young
bit on the pmd, that didn't have a range check but I think KVM will be
fine because the whole point of hugepages is that EPT/NPT will also
use a huge pmd when they notice gup returns pages with PageCompound set,
so they won't care of a range and there's just the pmd young bit to
check in that case.

NOTE: in some cases if the L2 cache is small, this may slowdown and
waste memory during COWs because 4M of memory are accessed in a single
fault instead of 8k (the payoff is that after COW the program can run
faster). So we might want to switch the copy_huge_page (and
clear_huge_page too) to not temporal stores. I also extensively
researched ways to avoid this cache trashing with a full prefault
logic that would cow in 8k/16k/32k/64k up to 1M (I can send those
patches that fully implemented prefault) but I concluded they're not
worth it and they add an huge additional complexity and they remove all tlb
benefits until the full hugepage has been faulted in, to save a little bit of
memory and some cache during app startup, but they still don't improve
substantially the cache-trashing during startup if the prefault happens in >4k
chunks.  One reason is that those 4k pte entries copied are still mapped on a
perfectly cache-colored hugepage, so the trashing is the worst one can generate
in those copies (cow of 4k page copies aren't so well colored so they trashes
less, but again this results in software running faster after the page fault).
Those prefault patches allowed things like a pte where post-cow pages were
local 4k regular anon pages and the not-yet-cowed pte entries were pointing in
the middle of some hugepage mapped read-only. If it doesn't payoff
substantially with todays hardware it will payoff even less in the future with
larger l2 caches, and the prefault logic would blot the VM a lot. If one is
emebdded transparent_hugepage can be disabled during boot with sysfs or with
the boot commandline parameter transparent_hugepage=0 (or
transparent_hugepage=2 to restrict hugepages inside madvise regions) that will
ensure not a single hugepage is allocated at boot time. It is simple enough to
just disable transparent hugepage globally and let transparent hugepages be
allocated selectively by applications in the MADV_HUGEPAGE region (both at page
fault time, and if enabled with the collapse_huge_page too through the kernel
daemon).

This patch supports only hugepages mapped in the pmd, archs that have
smaller hugepages will not fit in this patch alone. Also some archs like power
have certain tlb limits that prevents mixing different page size in the same
regions so they will not fit in this framework that requires "graceful
fallback" to basic PAGE_SIZE in case of physical memory fragmentation.
hugetlbfs remains a perfect fit for those because its software limits happen to
match the hardware limits. hugetlbfs also remains a perfect fit for hugepage
sizes like 1GByte that cannot be hoped to be found not fragmented after a
certain system uptime and that would be very expensive to defragment with
relocation, so requiring reservation. hugetlbfs is the "reservation way", the
point of transparent hugepages is not to have any reservation at all and
maximizing the use of cache and hugepages at all times automatically.

Some performance result:

vmx andrea # LD_PRELOAD=/usr/lib64/libhugetlbfs.so HUGETLB_MORECORE=yes HUGETLB_PATH=/mnt/huge/ ./largep
ages3
memset page fault 1566023
memset tlb miss 453854
memset second tlb miss 453321
random access tlb miss 41635
random access second tlb miss 41658
vmx andrea # LD_PRELOAD=/usr/lib64/libhugetlbfs.so HUGETLB_MORECORE=yes HUGETLB_PATH=/mnt/huge/ ./largepages3
memset page fault 1566471
memset tlb miss 453375
memset second tlb miss 453320
random access tlb miss 41636
random access second tlb miss 41637
vmx andrea # ./largepages3
memset page fault 1566642
memset tlb miss 453417
memset second tlb miss 453313
random access tlb miss 41630
random access second tlb miss 41647
vmx andrea # ./largepages3
memset page fault 1566872
memset tlb miss 453418
memset second tlb miss 453315
random access tlb miss 41618
random access second tlb miss 41659
vmx andrea # echo 0 > /proc/sys/vm/transparent_hugepage
vmx andrea # ./largepages3
memset page fault 2182476
memset tlb miss 460305
memset second tlb miss 460179
random access tlb miss 44483
random access second tlb miss 44186
vmx andrea # ./largepages3
memset page fault 2182791
memset tlb miss 460742
memset second tlb miss 459962
random access tlb miss 43981
random access second tlb miss 43988

============
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>

#define SIZE (3UL*1024*1024*1024)

int main()
{
	char *p = malloc(SIZE), *p2;
	struct timeval before, after;

	gettimeofday(&before, NULL);
	memset(p, 0, SIZE);
	gettimeofday(&after, NULL);
	printf("memset page fault %Lu\n",
	       (after.tv_sec-before.tv_sec)*1000000UL +
	       after.tv_usec-before.tv_usec);

	gettimeofday(&before, NULL);
	memset(p, 0, SIZE);
	gettimeofday(&after, NULL);
	printf("memset tlb miss %Lu\n",
	       (after.tv_sec-before.tv_sec)*1000000UL +
	       after.tv_usec-before.tv_usec);

	gettimeofday(&before, NULL);
	memset(p, 0, SIZE);
	gettimeofday(&after, NULL);
	printf("memset second tlb miss %Lu\n",
	       (after.tv_sec-before.tv_sec)*1000000UL +
	       after.tv_usec-before.tv_usec);

	gettimeofday(&before, NULL);
	for (p2 = p; p2 < p+SIZE; p2 += 4096)
		*p2 = 0;
	gettimeofday(&after, NULL);
	printf("random access tlb miss %Lu\n",
	       (after.tv_sec-before.tv_sec)*1000000UL +
	       after.tv_usec-before.tv_usec);

	gettimeofday(&before, NULL);
	for (p2 = p; p2 < p+SIZE; p2 += 4096)
		*p2 = 0;
	gettimeofday(&after, NULL);
	printf("random access second tlb miss %Lu\n",
	       (after.tv_sec-before.tv_sec)*1000000UL +
	       after.tv_usec-before.tv_usec);

	return 0;
}
============

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
* * *
adapt to mm_counter in -mm

From: Andrea Arcangeli <aarcange@redhat.com>

The interface changed slightly.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -286,6 +286,11 @@ static inline pmd_t pmd_mkwrite(pmd_t pm
 	return pmd_set_flags(pmd, _PAGE_RW);
 }
 
+static inline pmd_t pmd_mknotpresent(pmd_t pmd)
+{
+	return pmd_clear_flags(pmd, _PAGE_PRESENT);
+}
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* _ASM_X86_PGTABLE_64_H */
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -87,6 +87,9 @@ struct vm_area_struct;
 				 __GFP_HARDWALL | __GFP_HIGHMEM | \
 				 __GFP_MOVABLE)
 #define GFP_IOFS	(__GFP_IO | __GFP_FS)
+#define GFP_TRANSHUGE	(GFP_HIGHUSER_MOVABLE | __GFP_COMP | \
+			 __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN | \
+			 __GFP_NO_KSWAPD)
 
 #ifdef CONFIG_NUMA
 #define GFP_THISNODE	(__GFP_THISNODE | __GFP_NOWARN | __GFP_NORETRY)
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
new file mode 100644
--- /dev/null
+++ b/include/linux/huge_mm.h
@@ -0,0 +1,126 @@
+#ifndef _LINUX_HUGE_MM_H
+#define _LINUX_HUGE_MM_H
+
+extern int do_huge_pmd_anonymous_page(struct mm_struct *mm,
+				      struct vm_area_struct *vma,
+				      unsigned long address, pmd_t *pmd,
+				      unsigned int flags);
+extern int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+			 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
+			 struct vm_area_struct *vma);
+extern int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
+			       unsigned long address, pmd_t *pmd,
+			       pmd_t orig_pmd);
+extern pgtable_t get_pmd_huge_pte(struct mm_struct *mm);
+extern struct page *follow_trans_huge_pmd(struct mm_struct *mm,
+					  unsigned long addr,
+					  pmd_t *pmd,
+					  unsigned int flags);
+extern int zap_huge_pmd(struct mmu_gather *tlb,
+			struct vm_area_struct *vma,
+			pmd_t *pmd);
+
+enum transparent_hugepage_flag {
+	TRANSPARENT_HUGEPAGE_FLAG,
+	TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+	TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
+	TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
+#ifdef CONFIG_DEBUG_VM
+	TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG,
+#endif
+};
+
+enum page_check_address_pmd_flag {
+	PAGE_CHECK_ADDRESS_PMD_FLAG,
+	PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG,
+	PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG,
+};
+extern pmd_t *page_check_address_pmd(struct page *page,
+				     struct mm_struct *mm,
+				     unsigned long address,
+				     enum page_check_address_pmd_flag flag);
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define HPAGE_PMD_SHIFT HPAGE_SHIFT
+#define HPAGE_PMD_MASK HPAGE_MASK
+#define HPAGE_PMD_SIZE HPAGE_SIZE
+
+#define transparent_hugepage_enabled(__vma)				\
+	(transparent_hugepage_flags & (1<<TRANSPARENT_HUGEPAGE_FLAG) ||	\
+	 (transparent_hugepage_flags &					\
+	  (1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG) &&			\
+	  (__vma)->vm_flags & VM_HUGEPAGE))
+#define transparent_hugepage_defrag(__vma)				\
+	((transparent_hugepage_flags &					\
+	  (1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)) ||			\
+	 (transparent_hugepage_flags &					\
+	  (1<<TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG) &&		\
+	  (__vma)->vm_flags & VM_HUGEPAGE))
+#ifdef CONFIG_DEBUG_VM
+#define transparent_hugepage_debug_cow()				\
+	(transparent_hugepage_flags &					\
+	 (1<<TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG))
+#else /* CONFIG_DEBUG_VM */
+#define transparent_hugepage_debug_cow() 0
+#endif /* CONFIG_DEBUG_VM */
+
+extern unsigned long transparent_hugepage_flags;
+extern int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+			  pmd_t *dst_pmd, pmd_t *src_pmd,
+			  struct vm_area_struct *vma,
+			  unsigned long addr, unsigned long end);
+extern int handle_pte_fault(struct mm_struct *mm,
+			    struct vm_area_struct *vma, unsigned long address,
+			    pte_t *pte, pmd_t *pmd, unsigned int flags);
+extern int split_huge_page(struct page *page);
+extern void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd);
+#define split_huge_page_pmd(__mm, __pmd)				\
+	do {								\
+		pmd_t *____pmd = (__pmd);				\
+		if (unlikely(pmd_trans_huge(*____pmd)))			\
+			__split_huge_page_pmd(__mm, ____pmd);		\
+	}  while (0)
+#define wait_split_huge_page(__anon_vma, __pmd)				\
+	do {								\
+		pmd_t *____pmd = (__pmd);				\
+		spin_unlock_wait(&(__anon_vma)->lock);			\
+		/*							\
+		 * spin_unlock_wait() is just a loop in C and so the	\
+		 * CPU can reorder anything around it.			\
+		 */							\
+		smp_mb();						\
+		BUG_ON(pmd_trans_splitting(*____pmd) ||			\
+		       pmd_trans_huge(*____pmd));			\
+	} while (0)
+#define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
+#define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)
+#if HPAGE_PMD_ORDER > MAX_ORDER
+#error "hugepages can't be allocated by the buddy allocator"
+#endif
+
+extern unsigned long vma_address(struct page *page, struct vm_area_struct *vma);
+static inline int PageTransHuge(struct page *page)
+{
+	VM_BUG_ON(PageTail(page));
+	return PageHead(page);
+}
+#else /* CONFIG_TRANSPARENT_HUGEPAGE */
+#define HPAGE_PMD_SHIFT ({ BUG(); 0; })
+#define HPAGE_PMD_MASK ({ BUG(); 0; })
+#define HPAGE_PMD_SIZE ({ BUG(); 0; })
+
+#define transparent_hugepage_enabled(__vma) 0
+
+#define transparent_hugepage_flags 0UL
+static inline int split_huge_page(struct page *page)
+{
+	return 0;
+}
+#define split_huge_page_pmd(__mm, __pmd)	\
+	do { } while (0)
+#define wait_split_huge_page(__anon_vma, __pmd)	\
+	do { } while (0)
+#define PageTransHuge(page) 0
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
+#endif /* _LINUX_HUGE_MM_H */
diff --git a/include/linux/mm.h b/include/linux/mm.h
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -107,6 +107,9 @@ extern unsigned int kobjsize(const void 
 #define VM_SAO		0x20000000	/* Strong Access Ordering (powerpc) */
 #define VM_PFN_AT_MMAP	0x40000000	/* PFNMAP vma that is fully mapped at mmap time */
 #define VM_MERGEABLE	0x80000000	/* KSM may merge identical pages */
+#if BITS_PER_LONG > 32
+#define VM_HUGEPAGE	0x100000000UL	/* MADV_HUGEPAGE marked this vma */
+#endif
 
 #ifndef VM_STACK_DEFAULT_FLAGS		/* arch can override this */
 #define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
@@ -235,6 +238,7 @@ struct inode;
  * files which need it (119 of them)
  */
 #include <linux/page-flags.h>
+#include <linux/huge_mm.h>
 
 /*
  * Methods to modify the page usage count.
diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -20,11 +20,18 @@ static inline int page_is_file_cache(str
 }
 
 static inline void
+__add_page_to_lru_list(struct zone *zone, struct page *page, enum lru_list l,
+		       struct list_head *head)
+{
+	list_add(&page->lru, head);
+	__inc_zone_state(zone, NR_LRU_BASE + l);
+	mem_cgroup_add_lru_list(page, l);
+}
+
+static inline void
 add_page_to_lru_list(struct zone *zone, struct page *page, enum lru_list l)
 {
-	list_add(&page->lru, &zone->lru[l].list);
-	__inc_zone_state(zone, NR_LRU_BASE + l);
-	mem_cgroup_add_lru_list(page, l);
+	__add_page_to_lru_list(zone, page, l, &zone->lru[l].list);
 }
 
 static inline void
diff --git a/include/linux/swap.h b/include/linux/swap.h
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -205,6 +205,8 @@ extern unsigned int nr_free_pagecache_pa
 /* linux/mm/swap.c */
 extern void __lru_cache_add(struct page *, enum lru_list lru);
 extern void lru_cache_add_lru(struct page *, enum lru_list lru);
+extern void lru_add_page_tail(struct zone* zone,
+			      struct page *page, struct page *page_tail);
 extern void activate_page(struct page *);
 extern void mark_page_accessed(struct page *);
 extern void lru_add_drain(void);
diff --git a/mm/Makefile b/mm/Makefile
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -44,3 +44,4 @@ obj-$(CONFIG_MEMORY_FAILURE) += memory-f
 obj-$(CONFIG_HWPOISON_INJECT) += hwpoison-inject.o
 obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o
 obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o
+obj-$(CONFIG_TRANSPARENT_HUGEPAGE) += huge_memory.o
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
new file mode 100644
--- /dev/null
+++ b/mm/huge_memory.c
@@ -0,0 +1,867 @@
+/*
+ *  Copyright (C) 2009  Red Hat, Inc.
+ *
+ *  This work is licensed under the terms of the GNU GPL, version 2. See
+ *  the COPYING file in the top-level directory.
+ */
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/highmem.h>
+#include <linux/hugetlb.h>
+#include <linux/mmu_notifier.h>
+#include <linux/rmap.h>
+#include <linux/swap.h>
+#include <asm/tlb.h>
+#include <asm/pgalloc.h>
+#include "internal.h"
+
+unsigned long transparent_hugepage_flags __read_mostly =
+	(1<<TRANSPARENT_HUGEPAGE_FLAG);
+
+#ifdef CONFIG_SYSFS
+static ssize_t double_flag_show(struct kobject *kobj,
+				struct kobj_attribute *attr, char *buf,
+				enum transparent_hugepage_flag enabled,
+				enum transparent_hugepage_flag req_madv)
+{
+	if (test_bit(enabled, &transparent_hugepage_flags)) {
+		VM_BUG_ON(test_bit(req_madv, &transparent_hugepage_flags));
+		return sprintf(buf, "[always] madvise never\n");
+	} else if (test_bit(req_madv, &transparent_hugepage_flags))
+		return sprintf(buf, "always [madvise] never\n");
+	else
+		return sprintf(buf, "always madvise [never]\n");
+}
+static ssize_t double_flag_store(struct kobject *kobj,
+				 struct kobj_attribute *attr,
+				 const char *buf, size_t count,
+				 enum transparent_hugepage_flag enabled,
+				 enum transparent_hugepage_flag req_madv)
+{
+	if (!memcmp("always", buf,
+		    min(sizeof("always")-1, count))) {
+		set_bit(enabled, &transparent_hugepage_flags);
+		clear_bit(req_madv, &transparent_hugepage_flags);
+	} else if (!memcmp("madvise", buf,
+			   min(sizeof("madvise")-1, count))) {
+		clear_bit(enabled, &transparent_hugepage_flags);
+		set_bit(req_madv, &transparent_hugepage_flags);
+	} else if (!memcmp("never", buf,
+			   min(sizeof("never")-1, count))) {
+		clear_bit(enabled, &transparent_hugepage_flags);
+		clear_bit(req_madv, &transparent_hugepage_flags);
+	} else
+		return -EINVAL;
+
+	return count;
+}
+
+static ssize_t enabled_show(struct kobject *kobj,
+			    struct kobj_attribute *attr, char *buf)
+{
+	return double_flag_show(kobj, attr, buf,
+				TRANSPARENT_HUGEPAGE_FLAG,
+				TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
+}
+static ssize_t enabled_store(struct kobject *kobj,
+			     struct kobj_attribute *attr,
+			     const char *buf, size_t count)
+{
+	return double_flag_store(kobj, attr, buf, count,
+				 TRANSPARENT_HUGEPAGE_FLAG,
+				 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
+}
+static struct kobj_attribute enabled_attr =
+	__ATTR(enabled, 0644, enabled_show, enabled_store);
+
+static ssize_t single_flag_show(struct kobject *kobj,
+				struct kobj_attribute *attr, char *buf,
+				enum transparent_hugepage_flag flag)
+{
+	if (test_bit(flag, &transparent_hugepage_flags))
+		return sprintf(buf, "[yes] no\n");
+	else
+		return sprintf(buf, "yes [no]\n");
+}
+static ssize_t single_flag_store(struct kobject *kobj,
+				 struct kobj_attribute *attr,
+				 const char *buf, size_t count,
+				 enum transparent_hugepage_flag flag)
+{
+	if (!memcmp("yes", buf,
+		    min(sizeof("yes")-1, count))) {
+		set_bit(flag, &transparent_hugepage_flags);
+	} else if (!memcmp("no", buf,
+			   min(sizeof("no")-1, count))) {
+		clear_bit(flag, &transparent_hugepage_flags);
+	} else
+		return -EINVAL;
+
+	return count;
+}
+
+/*
+ * Currently defrag only disables __GFP_NOWAIT for allocation. A blind
+ * __GFP_REPEAT is too aggressive, it's never worth swapping tons of
+ * memory just to allocate one more hugepage.
+ */
+static ssize_t defrag_show(struct kobject *kobj,
+			   struct kobj_attribute *attr, char *buf)
+{
+	return double_flag_show(kobj, attr, buf,
+				TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
+				TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
+}
+static ssize_t defrag_store(struct kobject *kobj,
+			    struct kobj_attribute *attr,
+			    const char *buf, size_t count)
+{
+	return double_flag_store(kobj, attr, buf, count,
+				 TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
+				 TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG);
+}
+static struct kobj_attribute defrag_attr =
+	__ATTR(defrag, 0644, defrag_show, defrag_store);
+
+#ifdef CONFIG_DEBUG_VM
+static ssize_t debug_cow_show(struct kobject *kobj,
+				struct kobj_attribute *attr, char *buf)
+{
+	return single_flag_show(kobj, attr, buf,
+				TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
+}
+static ssize_t debug_cow_store(struct kobject *kobj,
+			       struct kobj_attribute *attr,
+			       const char *buf, size_t count)
+{
+	return single_flag_store(kobj, attr, buf, count,
+				 TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG);
+}
+static struct kobj_attribute debug_cow_attr =
+	__ATTR(debug_cow, 0644, debug_cow_show, debug_cow_store);
+#endif /* CONFIG_DEBUG_VM */
+
+static struct attribute *hugepage_attr[] = {
+	&enabled_attr.attr,
+	&defrag_attr.attr,
+#ifdef CONFIG_DEBUG_VM
+	&debug_cow_attr.attr,
+#endif
+	NULL,
+};
+
+static struct attribute_group hugepage_attr_group = {
+	.attrs = hugepage_attr,
+	.name = "transparent_hugepage",
+};
+#endif /* CONFIG_SYSFS */
+
+static int __init hugepage_init(void)
+{
+#ifdef CONFIG_SYSFS
+	int err;
+
+	err = sysfs_create_group(mm_kobj, &hugepage_attr_group);
+	if (err)
+		printk(KERN_ERR "hugepage: register sysfs failed\n");
+#endif
+	return 0;
+}
+module_init(hugepage_init)
+
+static int __init setup_transparent_hugepage(char *str)
+{
+	if (!str)
+		return 0;
+	transparent_hugepage_flags = simple_strtoul(str, &str, 0);
+	if (test_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags) &&
+	    test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+		     &transparent_hugepage_flags)) {
+		printk(KERN_WARNING
+		       "transparent_hugepage=%lu invalid parameter, disabling",
+		       transparent_hugepage_flags);
+		transparent_hugepage_flags = 0;
+	}
+	return 1;
+}
+__setup("transparent_hugepage=", setup_transparent_hugepage);
+
+static int __init setup_no_transparent_hugepage(char *str)
+{
+	transparent_hugepage_flags = 0;
+	return 1;
+}
+__setup("no_transparent_hugepage", setup_no_transparent_hugepage);
+
+static void prepare_pmd_huge_pte(pgtable_t pgtable,
+				 struct mm_struct *mm)
+{
+	VM_BUG_ON(spin_can_lock(&mm->page_table_lock));
+
+	/* FIFO */
+	if (!mm->pmd_huge_pte)
+		INIT_LIST_HEAD(&pgtable->lru);
+	else
+		list_add(&pgtable->lru, &mm->pmd_huge_pte->lru);
+	mm->pmd_huge_pte = pgtable;
+}
+
+static inline pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
+{
+	if (likely(vma->vm_flags & VM_WRITE))
+		pmd = pmd_mkwrite(pmd);
+	return pmd;
+}
+
+static int __do_huge_pmd_anonymous_page(struct mm_struct *mm,
+					struct vm_area_struct *vma,
+					unsigned long haddr, pmd_t *pmd,
+					struct page *page)
+{
+	int ret = 0;
+	pgtable_t pgtable;
+
+	VM_BUG_ON(!PageCompound(page));
+	pgtable = pte_alloc_one(mm, haddr);
+	if (unlikely(!pgtable)) {
+		put_page(page);
+		return VM_FAULT_OOM;
+	}
+
+	clear_huge_page(page, haddr, HPAGE_PMD_NR);
+	__SetPageUptodate(page);
+
+	spin_lock(&mm->page_table_lock);
+	if (unlikely(!pmd_none(*pmd))) {
+		spin_unlock(&mm->page_table_lock);
+		put_page(page);
+		pte_free(mm, pgtable);
+	} else {
+		pmd_t entry;
+		entry = mk_pmd(page, vma->vm_page_prot);
+		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
+		entry = pmd_mkhuge(entry);
+		/*
+		 * The spinlocking to take the lru_lock inside
+		 * page_add_new_anon_rmap() acts as a full memory
+		 * barrier to be sure clear_huge_page writes become
+		 * visible after the set_pmd_at() write.
+		 */
+		page_add_new_anon_rmap(page, vma, haddr);
+		set_pmd_at(mm, haddr, pmd, entry);
+		prepare_pmd_huge_pte(pgtable, mm);
+		add_mm_counter(mm, MM_ANONPAGES, HPAGE_PMD_NR);
+		spin_unlock(&mm->page_table_lock);
+	}
+
+	return ret;
+}
+
+static inline struct page *alloc_hugepage(int defrag)
+{
+	return alloc_pages(GFP_TRANSHUGE & ~(defrag ? 0 : __GFP_WAIT),
+			   HPAGE_PMD_ORDER);
+}
+
+int do_huge_pmd_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
+			       unsigned long address, pmd_t *pmd,
+			       unsigned int flags)
+{
+	struct page *page;
+	unsigned long haddr = address & HPAGE_PMD_MASK;
+	pte_t *pte;
+
+	if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) {
+		if (unlikely(anon_vma_prepare(vma)))
+			return VM_FAULT_OOM;
+		page = alloc_hugepage(transparent_hugepage_defrag(vma));
+		if (unlikely(!page))
+			goto out;
+
+		return __do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page);
+	}
+out:
+	pte = pte_alloc_map(mm, vma, pmd, address);
+	if (!pte)
+		return VM_FAULT_OOM;
+	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
+}
+
+int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+		  pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
+		  struct vm_area_struct *vma)
+{
+	struct page *src_page;
+	pmd_t pmd;
+	pgtable_t pgtable;
+	int ret;
+
+	ret = -ENOMEM;
+	pgtable = pte_alloc_one(dst_mm, addr);
+	if (unlikely(!pgtable))
+		goto out;
+
+	spin_lock(&dst_mm->page_table_lock);
+	spin_lock_nested(&src_mm->page_table_lock, SINGLE_DEPTH_NESTING);
+
+	ret = -EAGAIN;
+	pmd = *src_pmd;
+	if (unlikely(!pmd_trans_huge(pmd)))
+		goto out_unlock;
+	if (unlikely(pmd_trans_splitting(pmd))) {
+		/* split huge page running from under us */
+		spin_unlock(&src_mm->page_table_lock);
+		spin_unlock(&dst_mm->page_table_lock);
+
+		wait_split_huge_page(vma->anon_vma, src_pmd); /* src_vma */
+		goto out;
+	}
+	src_page = pmd_page(pmd);
+	VM_BUG_ON(!PageHead(src_page));
+	get_page(src_page);
+	page_dup_rmap(src_page);
+	add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR);
+
+	pmdp_set_wrprotect(src_mm, addr, src_pmd);
+	pmd = pmd_mkold(pmd_wrprotect(pmd));
+	set_pmd_at(dst_mm, addr, dst_pmd, pmd);
+	prepare_pmd_huge_pte(pgtable, dst_mm);
+
+	ret = 0;
+out_unlock:
+	spin_unlock(&src_mm->page_table_lock);
+	spin_unlock(&dst_mm->page_table_lock);
+out:
+	return ret;
+}
+
+/* no "address" argument so destroys page coloring of some arch */
+pgtable_t get_pmd_huge_pte(struct mm_struct *mm)
+{
+	pgtable_t pgtable;
+
+	VM_BUG_ON(spin_can_lock(&mm->page_table_lock));
+
+	/* FIFO */
+	pgtable = mm->pmd_huge_pte;
+	if (list_empty(&pgtable->lru))
+		mm->pmd_huge_pte = NULL;
+	else {
+		mm->pmd_huge_pte = list_entry(pgtable->lru.next,
+					      struct page, lru);
+		list_del(&pgtable->lru);
+	}
+	return pgtable;
+}
+
+static int do_huge_pmd_wp_page_fallback(struct mm_struct *mm,
+					struct vm_area_struct *vma,
+					unsigned long address,
+					pmd_t *pmd, pmd_t orig_pmd,
+					struct page *page,
+					unsigned long haddr)
+{
+	pgtable_t pgtable;
+	pmd_t _pmd;
+	int ret = 0, i;
+	struct page **pages;
+
+	pages = kmalloc(sizeof(struct page *) * HPAGE_PMD_NR,
+			GFP_KERNEL);
+	if (unlikely(!pages)) {
+		ret |= VM_FAULT_OOM;
+		goto out;
+	}
+
+	for (i = 0; i < HPAGE_PMD_NR; i++) {
+		pages[i] = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
+					  vma, address);
+		if (unlikely(!pages[i])) {
+			while (--i >= 0)
+				put_page(pages[i]);
+			kfree(pages);
+			ret |= VM_FAULT_OOM;
+			goto out;
+		}
+	}
+
+	spin_lock(&mm->page_table_lock);
+	if (unlikely(!pmd_same(*pmd, orig_pmd)))
+		goto out_free_pages;
+	else
+		get_page(page);
+	spin_unlock(&mm->page_table_lock);
+
+	for (i = 0; i < HPAGE_PMD_NR; i++) {
+		copy_user_highpage(pages[i], page + i,
+				   haddr + PAGE_SHIFT*i, vma);
+		__SetPageUptodate(pages[i]);
+		cond_resched();
+	}
+
+	spin_lock(&mm->page_table_lock);
+	if (unlikely(!pmd_same(*pmd, orig_pmd)))
+		goto out_free_pages;
+	else
+		put_page(page);
+
+	pmdp_clear_flush_notify(vma, haddr, pmd);
+	/* leave pmd empty until pte is filled */
+
+	pgtable = get_pmd_huge_pte(mm);
+	pmd_populate(mm, &_pmd, pgtable);
+
+	for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {
+		pte_t *pte, entry;
+		entry = mk_pte(pages[i], vma->vm_page_prot);
+		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+		page_add_new_anon_rmap(pages[i], vma, haddr);
+		pte = pte_offset_map(&_pmd, haddr);
+		VM_BUG_ON(!pte_none(*pte));
+		set_pte_at(mm, haddr, pte, entry);
+		pte_unmap(pte);
+	}
+	kfree(pages);
+
+	mm->nr_ptes++;
+	smp_wmb(); /* make pte visible before pmd */
+	pmd_populate(mm, pmd, pgtable);
+	page_remove_rmap(page);
+	spin_unlock(&mm->page_table_lock);
+
+	ret |= VM_FAULT_WRITE;
+	put_page(page);
+
+out:
+	return ret;
+
+out_free_pages:
+	spin_unlock(&mm->page_table_lock);
+	for (i = 0; i < HPAGE_PMD_NR; i++)
+		put_page(pages[i]);
+	kfree(pages);
+	goto out;
+}
+
+int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
+			unsigned long address, pmd_t *pmd, pmd_t orig_pmd)
+{
+	int ret = 0;
+	struct page *page, *new_page;
+	unsigned long haddr;
+
+	VM_BUG_ON(!vma->anon_vma);
+	spin_lock(&mm->page_table_lock);
+	if (unlikely(!pmd_same(*pmd, orig_pmd)))
+		goto out_unlock;
+
+	page = pmd_page(orig_pmd);
+	VM_BUG_ON(!PageCompound(page) || !PageHead(page));
+	haddr = address & HPAGE_PMD_MASK;
+	if (page_mapcount(page) == 1) {
+		pmd_t entry;
+		entry = pmd_mkyoung(orig_pmd);
+		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
+		if (pmdp_set_access_flags(vma, haddr, pmd, entry,  1))
+			update_mmu_cache(vma, address, entry);
+		ret |= VM_FAULT_WRITE;
+		goto out_unlock;
+	}
+	spin_unlock(&mm->page_table_lock);
+
+	if (transparent_hugepage_enabled(vma) &&
+	    !transparent_hugepage_debug_cow())
+		new_page = alloc_hugepage(transparent_hugepage_defrag(vma));
+	else
+		new_page = NULL;
+
+	if (unlikely(!new_page)) {
+		ret = do_huge_pmd_wp_page_fallback(mm, vma, address,
+						   pmd, orig_pmd, page, haddr);
+		goto out;
+	}
+
+	copy_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
+	__SetPageUptodate(new_page);
+
+	spin_lock(&mm->page_table_lock);
+	if (unlikely(!pmd_same(*pmd, orig_pmd)))
+		put_page(new_page);
+	else {
+		pmd_t entry;
+		entry = mk_pmd(new_page, vma->vm_page_prot);
+		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
+		entry = pmd_mkhuge(entry);
+		pmdp_clear_flush_notify(vma, haddr, pmd);
+		page_add_new_anon_rmap(new_page, vma, haddr);
+		set_pmd_at(mm, haddr, pmd, entry);
+		update_mmu_cache(vma, address, entry);
+		page_remove_rmap(page);
+		put_page(page);
+		ret |= VM_FAULT_WRITE;
+	}
+out_unlock:
+	spin_unlock(&mm->page_table_lock);
+out:
+	return ret;
+}
+
+struct page *follow_trans_huge_pmd(struct mm_struct *mm,
+				   unsigned long addr,
+				   pmd_t *pmd,
+				   unsigned int flags)
+{
+	struct page *page = NULL;
+
+	VM_BUG_ON(spin_can_lock(&mm->page_table_lock));
+
+	if (flags & FOLL_WRITE && !pmd_write(*pmd))
+		goto out;
+
+	page = pmd_page(*pmd);
+	VM_BUG_ON(!PageHead(page));
+	if (flags & FOLL_TOUCH) {
+		pmd_t _pmd;
+		/*
+		 * We should set the dirty bit only for FOLL_WRITE but
+		 * for now the dirty bit in the pmd is meaningless.
+		 * And if the dirty bit will become meaningful and
+		 * we'll only set it with FOLL_WRITE, an atomic
+		 * set_bit will be required on the pmd to set the
+		 * young bit, instead of the current set_pmd_at.
+		 */
+		_pmd = pmd_mkyoung(pmd_mkdirty(*pmd));
+		set_pmd_at(mm, addr & HPAGE_PMD_MASK, pmd, _pmd);
+	}
+	page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT;
+	VM_BUG_ON(!PageCompound(page));
+	if (flags & FOLL_GET)
+		get_page(page);
+
+out:
+	return page;
+}
+
+int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
+		 pmd_t *pmd)
+{
+	int ret = 0;
+
+	spin_lock(&tlb->mm->page_table_lock);
+	if (likely(pmd_trans_huge(*pmd))) {
+		if (unlikely(pmd_trans_splitting(*pmd))) {
+			spin_unlock(&tlb->mm->page_table_lock);
+			wait_split_huge_page(vma->anon_vma,
+					     pmd);
+		} else {
+			struct page *page;
+			pgtable_t pgtable;
+			pgtable = get_pmd_huge_pte(tlb->mm);
+			page = pmd_page(*pmd);
+			pmd_clear(pmd);
+			page_remove_rmap(page);
+			VM_BUG_ON(page_mapcount(page) < 0);
+			add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
+			spin_unlock(&tlb->mm->page_table_lock);
+			VM_BUG_ON(!PageHead(page));
+			tlb_remove_page(tlb, page);
+			pte_free(tlb->mm, pgtable);
+			ret = 1;
+		}
+	} else
+		spin_unlock(&tlb->mm->page_table_lock);
+
+	return ret;
+}
+
+pmd_t *page_check_address_pmd(struct page *page,
+			      struct mm_struct *mm,
+			      unsigned long address,
+			      enum page_check_address_pmd_flag flag)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd, *ret = NULL;
+
+	if (address & ~HPAGE_PMD_MASK)
+		goto out;
+
+	pgd = pgd_offset(mm, address);
+	if (!pgd_present(*pgd))
+		goto out;
+
+	pud = pud_offset(pgd, address);
+	if (!pud_present(*pud))
+		goto out;
+
+	pmd = pmd_offset(pud, address);
+	if (pmd_none(*pmd))
+		goto out;
+	if (pmd_page(*pmd) != page)
+		goto out;
+	VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG &&
+		  pmd_trans_splitting(*pmd));
+	if (pmd_trans_huge(*pmd)) {
+		VM_BUG_ON(flag == PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG &&
+			  !pmd_trans_splitting(*pmd));
+		ret = pmd;
+	}
+out:
+	return ret;
+}
+
+static int __split_huge_page_splitting(struct page *page,
+				       struct vm_area_struct *vma,
+				       unsigned long address)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	pmd_t *pmd;
+	int ret = 0;
+
+	spin_lock(&mm->page_table_lock);
+	pmd = page_check_address_pmd(page, mm, address,
+				     PAGE_CHECK_ADDRESS_PMD_NOTSPLITTING_FLAG);
+	if (pmd) {
+		/*
+		 * We can't temporarily set the pmd to null in order
+		 * to split it, the pmd must remain marked huge at all
+		 * times or the VM won't take the pmd_trans_huge paths
+		 * and it won't wait on the anon_vma->lock to
+		 * serialize against split_huge_page*.
+		 */
+		pmdp_splitting_flush_notify(vma, address, pmd);
+		ret = 1;
+	}
+	spin_unlock(&mm->page_table_lock);
+
+	return ret;
+}
+
+static void __split_huge_page_refcount(struct page *page)
+{
+	int i;
+	unsigned long head_index = page->index;
+	struct zone *zone = page_zone(page);
+
+	/* prevent PageLRU to go away from under us, and freeze lru stats */
+	spin_lock_irq(&zone->lru_lock);
+	compound_lock(page);
+
+	for (i = 1; i < HPAGE_PMD_NR; i++) {
+		struct page *page_tail = page + i;
+
+		/* tail_page->_count cannot change */
+		atomic_sub(atomic_read(&page_tail->_count), &page->_count);
+		BUG_ON(page_count(page) <= 0);
+		atomic_add(page_mapcount(page) + 1, &page_tail->_count);
+		BUG_ON(atomic_read(&page_tail->_count) <= 0);
+
+		/* after clearing PageTail the gup refcount can be released */
+		smp_mb();
+
+		page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+		page_tail->flags |= (page->flags &
+				     ((1L << PG_referenced) |
+				      (1L << PG_swapbacked) |
+				      (1L << PG_mlocked) |
+				      (1L << PG_uptodate)));
+		page_tail->flags |= (1L << PG_dirty);
+
+		/*
+		 * 1) clear PageTail before overwriting first_page
+		 * 2) clear PageTail before clearing PageHead for VM_BUG_ON
+		 */
+		smp_wmb();
+
+		/*
+		 * __split_huge_page_splitting() already set the
+		 * splitting bit in all pmd that could map this
+		 * hugepage, that will ensure no CPU can alter the
+		 * mapcount on the head page. The mapcount is only
+		 * accounted in the head page and it has to be
+		 * transferred to all tail pages in the below code. So
+		 * for this code to be safe, the split the mapcount
+		 * can't change. But that doesn't mean userland can't
+		 * keep changing and reading the page contents while
+		 * we transfer the mapcount, so the pmd splitting
+		 * status is achieved setting a reserved bit in the
+		 * pmd, not by clearing the present bit.
+		*/
+		BUG_ON(page_mapcount(page_tail));
+		page_tail->_mapcount = page->_mapcount;
+
+		BUG_ON(page_tail->mapping);
+		page_tail->mapping = page->mapping;
+
+		page_tail->index = ++head_index;
+
+		BUG_ON(!PageAnon(page_tail));
+		BUG_ON(!PageUptodate(page_tail));
+		BUG_ON(!PageDirty(page_tail));
+		BUG_ON(!PageSwapBacked(page_tail));
+
+		lru_add_page_tail(zone, page, page_tail);
+
+		put_page(page_tail);
+	}
+
+	ClearPageCompound(page);
+	compound_unlock(page);
+	spin_unlock_irq(&zone->lru_lock);
+
+	BUG_ON(page_count(page) <= 0);
+}
+
+static int __split_huge_page_map(struct page *page,
+				 struct vm_area_struct *vma,
+				 unsigned long address)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	pmd_t *pmd, _pmd;
+	int ret = 0, i;
+	pgtable_t pgtable;
+	unsigned long haddr;
+
+	spin_lock(&mm->page_table_lock);
+	pmd = page_check_address_pmd(page, mm, address,
+				     PAGE_CHECK_ADDRESS_PMD_SPLITTING_FLAG);
+	if (pmd) {
+		pgtable = get_pmd_huge_pte(mm);
+		pmd_populate(mm, &_pmd, pgtable);
+
+		for (i = 0, haddr = address; i < HPAGE_PMD_NR;
+		     i++, haddr += PAGE_SIZE) {
+			pte_t *pte, entry;
+			BUG_ON(PageCompound(page+i));
+			entry = mk_pte(page + i, vma->vm_page_prot);
+			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+			if (!pmd_write(*pmd))
+				entry = pte_wrprotect(entry);
+			else
+				BUG_ON(page_mapcount(page) != 1);
+			if (!pmd_young(*pmd))
+				entry = pte_mkold(entry);
+			pte = pte_offset_map(&_pmd, haddr);
+			BUG_ON(!pte_none(*pte));
+			set_pte_at(mm, haddr, pte, entry);
+			pte_unmap(pte);
+		}
+
+		mm->nr_ptes++;
+		smp_wmb(); /* make pte visible before pmd */
+		/*
+		 * Up to this point the pmd is present and huge and
+		 * userland has the whole access to the hugepage
+		 * during the split (which happens in place). If we
+		 * overwrite the pmd with the not-huge version
+		 * pointing to the pte here (which of course we could
+		 * if all CPUs were bug free), userland could trigger
+		 * a small page size TLB miss on the small sized TLB
+		 * while the hugepage TLB entry is still established
+		 * in the huge TLB. Some CPU doesn't like that. See
+		 * http://support.amd.com/us/Processor_TechDocs/41322.pdf,
+		 * Erratum 383 on page 93. Intel should be safe but is
+		 * also warns that it's only safe if the permission
+		 * and cache attributes of the two entries loaded in
+		 * the two TLB is identical (which should be the case
+		 * here). But it is generally safer to never allow
+		 * small and huge TLB entries for the same virtual
+		 * address to be loaded simultaneously. So instead of
+		 * doing "pmd_populate(); flush_tlb_range();" we first
+		 * mark the current pmd notpresent (atomically because
+		 * here the pmd_trans_huge and pmd_trans_splitting
+		 * must remain set at all times on the pmd until the
+		 * split is complete for this pmd), then we flush the
+		 * SMP TLB and finally we write the non-huge version
+		 * of the pmd entry with pmd_populate.
+		 */
+		set_pmd_at(mm, address, pmd, pmd_mknotpresent(*pmd));
+		flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
+		pmd_populate(mm, pmd, pgtable);
+		ret = 1;
+	}
+	spin_unlock(&mm->page_table_lock);
+
+	return ret;
+}
+
+/* must be called with anon_vma->lock hold */
+static void __split_huge_page(struct page *page,
+			      struct anon_vma *anon_vma)
+{
+	int mapcount, mapcount2;
+	struct anon_vma_chain *avc;
+
+	BUG_ON(!PageHead(page));
+	BUG_ON(PageTail(page));
+
+	mapcount = 0;
+	list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
+		struct vm_area_struct *vma = avc->vma;
+		unsigned long addr = vma_address(page, vma);
+		if (addr == -EFAULT)
+			continue;
+		mapcount += __split_huge_page_splitting(page, vma, addr);
+	}
+	BUG_ON(mapcount != page_mapcount(page));
+
+	__split_huge_page_refcount(page);
+
+	mapcount2 = 0;
+	list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
+		struct vm_area_struct *vma = avc->vma;
+		unsigned long addr = vma_address(page, vma);
+		if (addr == -EFAULT)
+			continue;
+		mapcount2 += __split_huge_page_map(page, vma, addr);
+	}
+	BUG_ON(mapcount != mapcount2);
+}
+
+int split_huge_page(struct page *page)
+{
+	struct anon_vma *anon_vma;
+	int ret = 1;
+
+	BUG_ON(!PageAnon(page));
+	anon_vma = page_lock_anon_vma(page);
+	if (!anon_vma)
+		goto out;
+	ret = 0;
+	if (!PageCompound(page))
+		goto out_unlock;
+
+	BUG_ON(!PageSwapBacked(page));
+	__split_huge_page(page, anon_vma);
+
+	BUG_ON(PageCompound(page));
+out_unlock:
+	page_unlock_anon_vma(anon_vma);
+out:
+	return ret;
+}
+
+void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd)
+{
+	struct page *page;
+
+	spin_lock(&mm->page_table_lock);
+	if (unlikely(!pmd_trans_huge(*pmd))) {
+		spin_unlock(&mm->page_table_lock);
+		return;
+	}
+	page = pmd_page(*pmd);
+	VM_BUG_ON(!page_count(page));
+	get_page(page);
+	spin_unlock(&mm->page_table_lock);
+
+	/*
+	 * The vma->anon_vma->lock is the wrong lock if the page is shared,
+	 * the anon_vma->lock pointed by page->mapping is the right one.
+	 */
+	split_huge_page(page);
+
+	put_page(page);
+	BUG_ON(pmd_trans_huge(*pmd));
+}
diff --git a/mm/memory.c b/mm/memory.c
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -728,9 +728,9 @@ out_set_pte:
 	return 0;
 }
 
-static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
-		pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
-		unsigned long addr, unsigned long end)
+int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
+		   pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
+		   unsigned long addr, unsigned long end)
 {
 	pte_t *orig_src_pte, *orig_dst_pte;
 	pte_t *src_pte, *dst_pte;
@@ -804,6 +804,16 @@ static inline int copy_pmd_range(struct 
 	src_pmd = pmd_offset(src_pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
+		if (pmd_trans_huge(*src_pmd)) {
+			int err;
+			err = copy_huge_pmd(dst_mm, src_mm,
+					    dst_pmd, src_pmd, addr, vma);
+			if (err == -ENOMEM)
+				return -ENOMEM;
+			if (!err)
+				continue;
+			/* fall through */
+		}
 		if (pmd_none_or_clear_bad(src_pmd))
 			continue;
 		if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
@@ -1006,6 +1016,15 @@ static inline unsigned long zap_pmd_rang
 	pmd = pmd_offset(pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
+		if (pmd_trans_huge(*pmd)) {
+			if (next-addr != HPAGE_PMD_SIZE)
+				split_huge_page_pmd(vma->vm_mm, pmd);
+			else if (zap_huge_pmd(tlb, vma, pmd)) {
+				(*zap_work)--;
+				continue;
+			}
+			/* fall through */
+		}
 		if (pmd_none_or_clear_bad(pmd)) {
 			(*zap_work)--;
 			continue;
@@ -1273,11 +1292,27 @@ struct page *follow_page(struct vm_area_
 	pmd = pmd_offset(pud, address);
 	if (pmd_none(*pmd))
 		goto no_page_table;
-	if (pmd_huge(*pmd)) {
+	if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
 		BUG_ON(flags & FOLL_GET);
 		page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
 		goto out;
 	}
+	if (pmd_trans_huge(*pmd)) {
+		spin_lock(&mm->page_table_lock);
+		if (likely(pmd_trans_huge(*pmd))) {
+			if (unlikely(pmd_trans_splitting(*pmd))) {
+				spin_unlock(&mm->page_table_lock);
+				wait_split_huge_page(vma->anon_vma, pmd);
+			} else {
+				page = follow_trans_huge_pmd(mm, address,
+							     pmd, flags);
+				spin_unlock(&mm->page_table_lock);
+				goto out;
+			}
+		} else
+			spin_unlock(&mm->page_table_lock);
+		/* fall through */
+	}
 	if (unlikely(pmd_bad(*pmd)))
 		goto no_page_table;
 
@@ -3045,9 +3080,9 @@ static int do_nonlinear_fault(struct mm_
  * but allow concurrent faults), and pte mapped but not yet locked.
  * We return with mmap_sem still held, but pte unmapped and unlocked.
  */
-static inline int handle_pte_fault(struct mm_struct *mm,
-		struct vm_area_struct *vma, unsigned long address,
-		pte_t *pte, pmd_t *pmd, unsigned int flags)
+int handle_pte_fault(struct mm_struct *mm,
+		     struct vm_area_struct *vma, unsigned long address,
+		     pte_t *pte, pmd_t *pmd, unsigned int flags)
 {
 	pte_t entry;
 	spinlock_t *ptl;
@@ -3126,6 +3161,22 @@ int handle_mm_fault(struct mm_struct *mm
 	pmd = pmd_alloc(mm, pud, address);
 	if (!pmd)
 		return VM_FAULT_OOM;
+	if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
+		if (!vma->vm_ops)
+			return do_huge_pmd_anonymous_page(mm, vma, address,
+							  pmd, flags);
+	} else {
+		pmd_t orig_pmd = *pmd;
+		barrier();
+		if (pmd_trans_huge(orig_pmd)) {
+			if (flags & FAULT_FLAG_WRITE &&
+			    !pmd_write(orig_pmd) &&
+			    !pmd_trans_splitting(orig_pmd))
+				return do_huge_pmd_wp_page(mm, vma, address,
+							   pmd, orig_pmd);
+			return 0;
+		}
+	}
 	pte = pte_alloc_map(mm, vma, pmd, address);
 	if (!pte)
 		return VM_FAULT_OOM;
diff --git a/mm/rmap.c b/mm/rmap.c
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -56,6 +56,7 @@
 #include <linux/memcontrol.h>
 #include <linux/mmu_notifier.h>
 #include <linux/migrate.h>
+#include <linux/hugetlb.h>
 
 #include <asm/tlbflush.h>
 
@@ -319,7 +320,7 @@ void page_unlock_anon_vma(struct anon_vm
  * Returns virtual address or -EFAULT if page's index/offset is not
  * within the range mapped the @vma.
  */
-static inline unsigned long
+inline unsigned long
 vma_address(struct page *page, struct vm_area_struct *vma)
 {
 	pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
@@ -433,35 +434,17 @@ int page_referenced_one(struct page *pag
 			unsigned long *vm_flags)
 {
 	struct mm_struct *mm = vma->vm_mm;
-	pte_t *pte;
-	spinlock_t *ptl;
 	int referenced = 0;
 
-	pte = page_check_address(page, mm, address, &ptl, 0);
-	if (!pte)
-		goto out;
-
 	/*
 	 * Don't want to elevate referenced for mlocked page that gets this far,
 	 * in order that it progresses to try_to_unmap and is moved to the
 	 * unevictable list.
 	 */
 	if (vma->vm_flags & VM_LOCKED) {
-		*mapcount = 1;	/* break early from loop */
+		*mapcount = 0;	/* break early from loop */
 		*vm_flags |= VM_LOCKED;
-		goto out_unmap;
-	}
-
-	if (ptep_clear_flush_young_notify(vma, address, pte)) {
-		/*
-		 * Don't treat a reference through a sequentially read
-		 * mapping as such.  If the page has been used in
-		 * another mapping, we will catch it; if this other
-		 * mapping is already gone, the unmap path will have
-		 * set PG_referenced or activated the page.
-		 */
-		if (likely(!VM_SequentialReadHint(vma)))
-			referenced++;
+		goto out;
 	}
 
 	/* Pretend the page is referenced if the task has the
@@ -470,9 +453,39 @@ int page_referenced_one(struct page *pag
 			rwsem_is_locked(&mm->mmap_sem))
 		referenced++;
 
-out_unmap:
+	if (unlikely(PageTransHuge(page))) {
+		pmd_t *pmd;
+
+		spin_lock(&mm->page_table_lock);
+		pmd = page_check_address_pmd(page, mm, address,
+					     PAGE_CHECK_ADDRESS_PMD_FLAG);
+		if (pmd && !pmd_trans_splitting(*pmd) &&
+		    pmdp_clear_flush_young_notify(vma, address, pmd))
+			referenced++;
+		spin_unlock(&mm->page_table_lock);
+	} else {
+		pte_t *pte;
+		spinlock_t *ptl;
+
+		pte = page_check_address(page, mm, address, &ptl, 0);
+		if (!pte)
+			goto out;
+
+		if (ptep_clear_flush_young_notify(vma, address, pte)) {
+			/*
+			 * Don't treat a reference through a sequentially read
+			 * mapping as such.  If the page has been used in
+			 * another mapping, we will catch it; if this other
+			 * mapping is already gone, the unmap path will have
+			 * set PG_referenced or activated the page.
+			 */
+			if (likely(!VM_SequentialReadHint(vma)))
+				referenced++;
+		}
+		pte_unmap_unlock(pte, ptl);
+	}
+
 	(*mapcount)--;
-	pte_unmap_unlock(pte, ptl);
 
 	if (referenced)
 		*vm_flags |= vma->vm_flags;
diff --git a/mm/swap.c b/mm/swap.c
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -462,6 +462,43 @@ void __pagevec_release(struct pagevec *p
 
 EXPORT_SYMBOL(__pagevec_release);
 
+/* used by __split_huge_page_refcount() */
+void lru_add_page_tail(struct zone* zone,
+		       struct page *page, struct page *page_tail)
+{
+	int active;
+	enum lru_list lru;
+	const int file = 0;
+	struct list_head *head;
+
+	VM_BUG_ON(!PageHead(page));
+	VM_BUG_ON(PageCompound(page_tail));
+	VM_BUG_ON(PageLRU(page_tail));
+	VM_BUG_ON(!spin_is_locked(&zone->lru_lock));
+
+	SetPageLRU(page_tail);
+
+	if (page_evictable(page_tail, NULL)) {
+		if (PageActive(page)) {
+			SetPageActive(page_tail);
+			active = 1;
+			lru = LRU_ACTIVE_ANON;
+		} else {
+			active = 0;
+			lru = LRU_INACTIVE_ANON;
+		}
+		update_page_reclaim_stat(zone, page_tail, file, active);
+		if (likely(PageLRU(page)))
+			head = page->lru.prev;
+		else
+			head = &zone->lru[lru].list;
+		__add_page_to_lru_list(zone, page_tail, lru, head);
+	} else {
+		SetPageUnevictable(page_tail);
+		add_page_to_lru_list(zone, page_tail, LRU_UNEVICTABLE);
+	}
+}
+
 /*
  * Add the passed pages to the LRU, then drop the caller's refcount
  * on them.  Reinitialises the caller's pagevec.

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[PATCH 32 of 67] verify pmd_trans_huge isn't leaking

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

pte_trans_huge must not leak in certain vmas like the mmio special pfn or
filebacked mappings.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/mm/memory.c b/mm/memory.c
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1421,6 +1421,7 @@ int __get_user_pages(struct task_struct 
 			pmd = pmd_offset(pud, pg);
 			if (pmd_none(*pmd))
 				return i ? : -EFAULT;
+			VM_BUG_ON(pmd_trans_huge(*pmd));
 			pte = pte_offset_map(pmd, pg);
 			if (pte_none(*pte)) {
 				pte_unmap(pte);
@@ -1622,8 +1623,10 @@ pte_t *get_locked_pte(struct mm_struct *
 	pud_t * pud = pud_alloc(mm, pgd, addr);
 	if (pud) {
 		pmd_t * pmd = pmd_alloc(mm, pud, addr);
-		if (pmd)
+		if (pmd) {
+			VM_BUG_ON(pmd_trans_huge(*pmd));
 			return pte_alloc_map_lock(mm, pmd, addr, ptl);
+		}
 	}
 	return NULL;
 }
@@ -1842,6 +1845,7 @@ static inline int remap_pmd_range(struct
 	pmd = pmd_alloc(mm, pud, addr);
 	if (!pmd)
 		return -ENOMEM;
+	VM_BUG_ON(pmd_trans_huge(*pmd));
 	do {
 		next = pmd_addr_end(addr, end);
 		if (remap_pte_range(mm, pmd, addr, next,
@@ -3317,6 +3321,7 @@ static int follow_pte(struct mm_struct *
 		goto out;
 
 	pmd = pmd_offset(pud, address);
+	VM_BUG_ON(pmd_trans_huge(*pmd));
 	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
 		goto out;
 

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[PATCH 33 of 67] madvise(MADV_HUGEPAGE)

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Add madvise MADV_HUGEPAGE to mark regions that are important to be hugepage
backed. Return -EINVAL if the vma is not of an anonymous type, or the feature
isn't built into the kernel. Never silently return success.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -99,6 +99,7 @@ extern void __split_huge_page_pmd(struct
 #endif
 
 extern unsigned long vma_address(struct page *page, struct vm_area_struct *vma);
+extern int hugepage_madvise(unsigned long *vm_flags);
 static inline int PageTransHuge(struct page *page)
 {
 	VM_BUG_ON(PageTail(page));
@@ -121,6 +122,11 @@ static inline int split_huge_page(struct
 #define wait_split_huge_page(__anon_vma, __pmd)	\
 	do { } while (0)
 #define PageTransHuge(page) 0
+static inline int hugepage_madvise(unsigned long *vm_flags)
+{
+	BUG_ON(0);
+	return 0;
+}
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 #endif /* _LINUX_HUGE_MM_H */
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -842,6 +842,22 @@ out:
 	return ret;
 }
 
+int hugepage_madvise(unsigned long *vm_flags)
+{
+	/*
+	 * Be somewhat over-protective like KSM for now!
+	 */
+	if (*vm_flags & (VM_HUGEPAGE | VM_SHARED  | VM_MAYSHARE   |
+			 VM_PFNMAP   | VM_IO      | VM_DONTEXPAND |
+			 VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE |
+			 VM_MIXEDMAP | VM_SAO))
+		return -EINVAL;
+
+	*vm_flags |= VM_HUGEPAGE;
+
+	return 0;
+}
+
 void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd)
 {
 	struct page *page;
diff --git a/mm/madvise.c b/mm/madvise.c
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -71,6 +71,11 @@ static long madvise_behavior(struct vm_a
 		if (error)
 			goto out;
 		break;
+	case MADV_HUGEPAGE:
+		error = hugepage_madvise(&new_flags);
+		if (error)
+			goto out;
+		break;
 	}
 
 	if (new_flags == vma->vm_flags) {
@@ -283,6 +288,9 @@ madvise_behavior_valid(int behavior)
 	case MADV_MERGEABLE:
 	case MADV_UNMERGEABLE:
 #endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	case MADV_HUGEPAGE:
+#endif
 		return 1;
 
 	default:

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[PATCH 34 of 67] pmd_trans_huge migrate bugcheck

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

No pmd_trans_huge should ever materialize in migration ptes areas, because
we split the hugepage before migration ptes are instantiated.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -105,6 +105,10 @@ static inline int PageTransHuge(struct p
 	VM_BUG_ON(PageTail(page));
 	return PageHead(page);
 }
+static inline int PageTransCompound(struct page *page)
+{
+	return PageCompound(page);
+}
 #else /* CONFIG_TRANSPARENT_HUGEPAGE */
 #define HPAGE_PMD_SHIFT ({ BUG(); 0; })
 #define HPAGE_PMD_MASK ({ BUG(); 0; })
@@ -122,6 +126,7 @@ static inline int split_huge_page(struct
 #define wait_split_huge_page(__anon_vma, __pmd)	\
 	do { } while (0)
 #define PageTransHuge(page) 0
+#define PageTransCompound(page) 0
 static inline int hugepage_madvise(unsigned long *vm_flags)
 {
 	BUG_ON(0);
diff --git a/mm/migrate.c b/mm/migrate.c
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -100,6 +100,7 @@ static int remove_migration_pte(struct p
 		goto out;
 
 	pmd = pmd_offset(pud, addr);
+	VM_BUG_ON(pmd_trans_huge(*pmd));
 	if (!pmd_present(*pmd))
 		goto out;
 
@@ -556,6 +557,9 @@ static int unmap_and_move(new_page_t get
 		/* page was freed from under us. So we are done. */
 		goto move_newpage;
 	}
+	if (unlikely(PageTransHuge(page)))
+		if (unlikely(split_huge_page(page)))
+			goto move_newpage;
 
 	/* prepare cgroup just returns 0 or -ENOMEM */
 	rc = -EAGAIN;
@@ -816,6 +820,10 @@ static int do_move_page_to_node_array(st
 		if (PageReserved(page) || PageKsm(page))
 			goto put_and_set;
 
+		if (unlikely(PageTransCompound(page)))
+			if (unlikely(split_huge_page(page)))
+				goto put_and_set;
+
 		pp->page = page;
 		err = page_to_nid(page);
 

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[PATCH 35 of 67] memcg compound

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Teach memcg to charge/uncharge compound pages.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -4,6 +4,10 @@ NOTE: The Memory Resource Controller has
 to as the memory controller in this document. Do not confuse memory controller
 used here with the memory controller that is used in hardware.
 
+NOTE: When in this documentation we refer to PAGE_SIZE, we actually
+mean the real page size of the page being accounted which is bigger than
+PAGE_SIZE for compound pages.
+
 Salient features
 
 a. Enable control of Anonymous, Page Cache (mapped and unmapped) and
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1509,12 +1509,14 @@ static int __cpuinit memcg_stock_cpu_cal
  * oom-killer can be invoked.
  */
 static int __mem_cgroup_try_charge(struct mm_struct *mm,
-			gfp_t gfp_mask, struct mem_cgroup **memcg, bool oom)
+				   gfp_t gfp_mask,
+				   struct mem_cgroup **memcg, bool oom,
+				   int page_size)
 {
 	struct mem_cgroup *mem, *mem_over_limit;
 	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
 	struct res_counter *fail_res;
-	int csize = CHARGE_SIZE;
+	int csize = max(CHARGE_SIZE, (unsigned long) page_size);
 
 	/*
 	 * Unlike gloval-vm's OOM-kill, we're not in memory shortage
@@ -1549,8 +1551,9 @@ static int __mem_cgroup_try_charge(struc
 		int ret = 0;
 		unsigned long flags = 0;
 
-		if (consume_stock(mem))
-			goto done;
+		if (page_size == PAGE_SIZE)
+			if (consume_stock(mem))
+				goto done;
 
 		ret = res_counter_charge(&mem->res, csize, &fail_res);
 		if (likely(!ret)) {
@@ -1570,8 +1573,8 @@ static int __mem_cgroup_try_charge(struc
 									res);
 
 		/* reduce request size and retry */
-		if (csize > PAGE_SIZE) {
-			csize = PAGE_SIZE;
+		if (csize > page_size) {
+			csize = page_size;
 			continue;
 		}
 		if (!(gfp_mask & __GFP_WAIT))
@@ -1647,8 +1650,10 @@ static int __mem_cgroup_try_charge(struc
 			goto bypass;
 		}
 	}
-	if (csize > PAGE_SIZE)
-		refill_stock(mem, csize - PAGE_SIZE);
+	if (csize > page_size)
+		refill_stock(mem, csize - page_size);
+	if (page_size != PAGE_SIZE)
+		__css_get(&mem->css, page_size);
 done:
 	return 0;
 nomem:
@@ -1678,9 +1683,10 @@ static void __mem_cgroup_cancel_charge(s
 	/* we don't need css_put for root */
 }
 
-static void mem_cgroup_cancel_charge(struct mem_cgroup *mem)
+static void mem_cgroup_cancel_charge(struct mem_cgroup *mem,
+				     int page_size)
 {
-	__mem_cgroup_cancel_charge(mem, 1);
+	__mem_cgroup_cancel_charge(mem, page_size >> PAGE_SHIFT);
 }
 
 /*
@@ -1736,8 +1742,9 @@ struct mem_cgroup *try_get_mem_cgroup_fr
  */
 
 static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
-				     struct page_cgroup *pc,
-				     enum charge_type ctype)
+				       struct page_cgroup *pc,
+				       enum charge_type ctype,
+				       int page_size)
 {
 	/* try_charge() can return NULL to *memcg, taking care of it. */
 	if (!mem)
@@ -1746,7 +1753,7 @@ static void __mem_cgroup_commit_charge(s
 	lock_page_cgroup(pc);
 	if (unlikely(PageCgroupUsed(pc))) {
 		unlock_page_cgroup(pc);
-		mem_cgroup_cancel_charge(mem);
+		mem_cgroup_cancel_charge(mem, page_size);
 		return;
 	}
 
@@ -1820,7 +1827,7 @@ static void __mem_cgroup_move_account(st
 	mem_cgroup_charge_statistics(from, pc, false);
 	if (uncharge)
 		/* This is not "cancel", but cancel_charge does all we need. */
-		mem_cgroup_cancel_charge(from);
+		mem_cgroup_cancel_charge(from, PAGE_SIZE);
 
 	/* caller should have done css_get */
 	pc->mem_cgroup = to;
@@ -1881,13 +1888,14 @@ static int mem_cgroup_move_parent(struct
 		goto put;
 
 	parent = mem_cgroup_from_cont(pcg);
-	ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false);
+	ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false,
+				      PAGE_SIZE);
 	if (ret || !parent)
 		goto put_back;
 
 	ret = mem_cgroup_move_account(pc, child, parent, true);
 	if (ret)
-		mem_cgroup_cancel_charge(parent);
+		mem_cgroup_cancel_charge(parent, PAGE_SIZE);
 put_back:
 	putback_lru_page(page);
 put:
@@ -1909,6 +1917,10 @@ static int mem_cgroup_charge_common(stru
 	struct mem_cgroup *mem;
 	struct page_cgroup *pc;
 	int ret;
+	int page_size = PAGE_SIZE;
+
+	if (PageTransHuge(page))
+		page_size <<= compound_order(page);
 
 	pc = lookup_page_cgroup(page);
 	/* can happen at boot */
@@ -1917,11 +1929,11 @@ static int mem_cgroup_charge_common(stru
 	prefetchw(pc);
 
 	mem = memcg;
-	ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true);
+	ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true, page_size);
 	if (ret || !mem)
 		return ret;
 
-	__mem_cgroup_commit_charge(mem, pc, ctype);
+	__mem_cgroup_commit_charge(mem, pc, ctype, page_size);
 	return 0;
 }
 
@@ -1930,8 +1942,6 @@ int mem_cgroup_newpage_charge(struct pag
 {
 	if (mem_cgroup_disabled())
 		return 0;
-	if (PageCompound(page))
-		return 0;
 	/*
 	 * If already mapped, we don't have to account.
 	 * If page cache, page->mapping has address_space.
@@ -1944,7 +1954,7 @@ int mem_cgroup_newpage_charge(struct pag
 	if (unlikely(!mm))
 		mm = &init_mm;
 	return mem_cgroup_charge_common(page, mm, gfp_mask,
-				MEM_CGROUP_CHARGE_TYPE_MAPPED, NULL);
+					MEM_CGROUP_CHARGE_TYPE_MAPPED, NULL);
 }
 
 static void
@@ -2037,14 +2047,14 @@ int mem_cgroup_try_charge_swapin(struct 
 	if (!mem)
 		goto charge_cur_mm;
 	*ptr = mem;
-	ret = __mem_cgroup_try_charge(NULL, mask, ptr, true);
+	ret = __mem_cgroup_try_charge(NULL, mask, ptr, true, PAGE_SIZE);
 	/* drop extra refcnt from tryget */
 	css_put(&mem->css);
 	return ret;
 charge_cur_mm:
 	if (unlikely(!mm))
 		mm = &init_mm;
-	return __mem_cgroup_try_charge(mm, mask, ptr, true);
+	return __mem_cgroup_try_charge(mm, mask, ptr, true, PAGE_SIZE);
 }
 
 static void
@@ -2060,7 +2070,7 @@ __mem_cgroup_commit_charge_swapin(struct
 	cgroup_exclude_rmdir(&ptr->css);
 	pc = lookup_page_cgroup(page);
 	mem_cgroup_lru_del_before_commit_swapcache(page);
-	__mem_cgroup_commit_charge(ptr, pc, ctype);
+	__mem_cgroup_commit_charge(ptr, pc, ctype, PAGE_SIZE);
 	mem_cgroup_lru_add_after_commit_swapcache(page);
 	/*
 	 * Now swap is on-memory. This means this page may be
@@ -2109,11 +2119,12 @@ void mem_cgroup_cancel_charge_swapin(str
 		return;
 	if (!mem)
 		return;
-	mem_cgroup_cancel_charge(mem);
+	mem_cgroup_cancel_charge(mem, PAGE_SIZE);
 }
 
 static void
-__do_uncharge(struct mem_cgroup *mem, const enum charge_type ctype)
+__do_uncharge(struct mem_cgroup *mem, const enum charge_type ctype,
+	      int page_size)
 {
 	struct memcg_batch_info *batch = NULL;
 	bool uncharge_memsw = true;
@@ -2146,14 +2157,14 @@ __do_uncharge(struct mem_cgroup *mem, co
 	if (batch->memcg != mem)
 		goto direct_uncharge;
 	/* remember freed charge and uncharge it later */
-	batch->bytes += PAGE_SIZE;
+	batch->bytes += page_size;
 	if (uncharge_memsw)
-		batch->memsw_bytes += PAGE_SIZE;
+		batch->memsw_bytes += page_size;
 	return;
 direct_uncharge:
-	res_counter_uncharge(&mem->res, PAGE_SIZE);
+	res_counter_uncharge(&mem->res, page_size);
 	if (uncharge_memsw)
-		res_counter_uncharge(&mem->memsw, PAGE_SIZE);
+		res_counter_uncharge(&mem->memsw, page_size);
 	return;
 }
 
@@ -2166,6 +2177,10 @@ __mem_cgroup_uncharge_common(struct page
 	struct page_cgroup *pc;
 	struct mem_cgroup *mem = NULL;
 	struct mem_cgroup_per_zone *mz;
+	int page_size = PAGE_SIZE;
+
+	if (PageTransHuge(page))
+		page_size <<= compound_order(page);
 
 	if (mem_cgroup_disabled())
 		return NULL;
@@ -2205,7 +2220,7 @@ __mem_cgroup_uncharge_common(struct page
 	}
 
 	if (!mem_cgroup_is_root(mem))
-		__do_uncharge(mem, ctype);
+		__do_uncharge(mem, ctype, page_size);
 	if (ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
 		mem_cgroup_swap_statistics(mem, true);
 	mem_cgroup_charge_statistics(mem, pc, false);
@@ -2418,6 +2433,7 @@ int mem_cgroup_prepare_migration(struct 
 	struct mem_cgroup *mem = NULL;
 	int ret = 0;
 
+	VM_BUG_ON(PageTransHuge(page));
 	if (mem_cgroup_disabled())
 		return 0;
 
@@ -2430,7 +2446,8 @@ int mem_cgroup_prepare_migration(struct 
 	unlock_page_cgroup(pc);
 
 	if (mem) {
-		ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false);
+		ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false,
+					      PAGE_SIZE);
 		css_put(&mem->css);
 	}
 	*ptr = mem;
@@ -2473,7 +2490,7 @@ void mem_cgroup_end_migration(struct mem
 	 * __mem_cgroup_commit_charge() check PCG_USED bit of page_cgroup.
 	 * So, double-counting is effectively avoided.
 	 */
-	__mem_cgroup_commit_charge(mem, pc, ctype);
+	__mem_cgroup_commit_charge(mem, pc, ctype, PAGE_SIZE);
 
 	/*
 	 * Both of oldpage and newpage are still under lock_page().
@@ -3940,7 +3957,8 @@ one_by_one:
 			batch_count = PRECHARGE_COUNT_AT_ONCE;
 			cond_resched();
 		}
-		ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false);
+		ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false,
+					      PAGE_SIZE);
 		if (ret || !mem)
 			/* mem_cgroup_clear_mc() will do uncharge later */
 			return -ENOMEM;
@@ -4055,6 +4073,7 @@ static int mem_cgroup_count_precharge_pt
 	pte_t *pte;
 	spinlock_t *ptl;
 
+	VM_BUG_ON(pmd_trans_huge(*pmd));
 	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
 	for (; addr != end; pte++, addr += PAGE_SIZE)
 		if (is_target_pte_for_mc(vma, addr, *pte, NULL))
@@ -4201,6 +4220,7 @@ static int mem_cgroup_move_charge_pte_ra
 	spinlock_t *ptl;
 
 retry:
+	VM_BUG_ON(pmd_trans_huge(*pmd));
 	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
 	for (; addr != end; addr += PAGE_SIZE) {
 		pte_t ptent = *(pte++);

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[PATCH 36 of 67] memcg huge memory

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Add memcg charge/uncharge to hugepage faults in huge_memory.c.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -225,6 +225,7 @@ static int __do_huge_pmd_anonymous_page(
 	VM_BUG_ON(!PageCompound(page));
 	pgtable = pte_alloc_one(mm, haddr);
 	if (unlikely(!pgtable)) {
+		mem_cgroup_uncharge_page(page);
 		put_page(page);
 		return VM_FAULT_OOM;
 	}
@@ -235,6 +236,7 @@ static int __do_huge_pmd_anonymous_page(
 	spin_lock(&mm->page_table_lock);
 	if (unlikely(!pmd_none(*pmd))) {
 		spin_unlock(&mm->page_table_lock);
+		mem_cgroup_uncharge_page(page);
 		put_page(page);
 		pte_free(mm, pgtable);
 	} else {
@@ -278,6 +280,10 @@ int do_huge_pmd_anonymous_page(struct mm
 		page = alloc_hugepage(transparent_hugepage_defrag(vma));
 		if (unlikely(!page))
 			goto out;
+		if (unlikely(mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))) {
+			put_page(page);
+			goto out;
+		}
 
 		return __do_huge_pmd_anonymous_page(mm, vma, haddr, pmd, page);
 	}
@@ -377,9 +383,15 @@ static int do_huge_pmd_wp_page_fallback(
 	for (i = 0; i < HPAGE_PMD_NR; i++) {
 		pages[i] = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
 					  vma, address);
-		if (unlikely(!pages[i])) {
-			while (--i >= 0)
+		if (unlikely(!pages[i] ||
+			     mem_cgroup_newpage_charge(pages[i], mm,
+						       GFP_KERNEL))) {
+			if (pages[i])
 				put_page(pages[i]);
+			while (--i >= 0) {
+				mem_cgroup_uncharge_page(pages[i]);
+				put_page(pages[i]);
+			}
 			kfree(pages);
 			ret |= VM_FAULT_OOM;
 			goto out;
@@ -438,8 +450,10 @@ out:
 
 out_free_pages:
 	spin_unlock(&mm->page_table_lock);
-	for (i = 0; i < HPAGE_PMD_NR; i++)
+	for (i = 0; i < HPAGE_PMD_NR; i++) {
+		mem_cgroup_uncharge_page(pages[i]);
 		put_page(pages[i]);
+	}
 	kfree(pages);
 	goto out;
 }
@@ -482,13 +496,19 @@ int do_huge_pmd_wp_page(struct mm_struct
 		goto out;
 	}
 
+	if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {
+		put_page(new_page);
+		ret |= VM_FAULT_OOM;
+		goto out;
+	}
 	copy_huge_page(new_page, page, haddr, vma, HPAGE_PMD_NR);
 	__SetPageUptodate(new_page);
 
 	spin_lock(&mm->page_table_lock);
-	if (unlikely(!pmd_same(*pmd, orig_pmd)))
+	if (unlikely(!pmd_same(*pmd, orig_pmd))) {
+		mem_cgroup_uncharge_page(new_page);
 		put_page(new_page);
-	else {
+	} else {
 		pmd_t entry;
 		entry = mk_pmd(new_page, vma->vm_page_prot);
 		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);

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[PATCH 37 of 67] transparent hugepage vmstat

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Add hugepage stat information to /proc/vmstat and /proc/meminfo.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
--- a/fs/proc/meminfo.c
+++ b/fs/proc/meminfo.c
@@ -101,6 +101,9 @@ static int meminfo_proc_show(struct seq_
 #ifdef CONFIG_MEMORY_FAILURE
 		"HardwareCorrupted: %5lu kB\n"
 #endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+		"AnonHugePages:  %8lu kB\n"
+#endif
 		,
 		K(i.totalram),
 		K(i.freeram),
@@ -151,6 +154,10 @@ static int meminfo_proc_show(struct seq_
 #ifdef CONFIG_MEMORY_FAILURE
 		,atomic_long_read(&mce_bad_pages) << (PAGE_SHIFT - 10)
 #endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+		,K(global_page_state(NR_ANON_TRANSPARENT_HUGEPAGES) *
+		   HPAGE_PMD_NR)
+#endif
 		);
 
 	hugetlb_report_meminfo(m);
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -112,6 +112,7 @@ enum zone_stat_item {
 	NUMA_LOCAL,		/* allocation from local node */
 	NUMA_OTHER,		/* allocation from other node */
 #endif
+	NR_ANON_TRANSPARENT_HUGEPAGES,
 	NR_VM_ZONE_STAT_ITEMS };
 
 /*
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -726,6 +726,9 @@ static void __split_huge_page_refcount(s
 		put_page(page_tail);
 	}
 
+	__dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
+	__mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR);
+
 	ClearPageCompound(page);
 	compound_unlock(page);
 	spin_unlock_irq(&zone->lru_lock);
diff --git a/mm/rmap.c b/mm/rmap.c
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -796,8 +796,13 @@ void page_add_anon_rmap(struct page *pag
 	struct vm_area_struct *vma, unsigned long address)
 {
 	int first = atomic_inc_and_test(&page->_mapcount);
-	if (first)
-		__inc_zone_page_state(page, NR_ANON_PAGES);
+	if (first) {
+		if (!PageTransHuge(page))
+			__inc_zone_page_state(page, NR_ANON_PAGES);
+		else
+			__inc_zone_page_state(page,
+					      NR_ANON_TRANSPARENT_HUGEPAGES);
+	}
 	if (unlikely(PageKsm(page)))
 		return;
 
@@ -825,7 +830,10 @@ void page_add_new_anon_rmap(struct page 
 	VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
 	SetPageSwapBacked(page);
 	atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */
-	__inc_zone_page_state(page, NR_ANON_PAGES);
+	if (!PageTransHuge(page))
+	    __inc_zone_page_state(page, NR_ANON_PAGES);
+	else
+	    __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
 	__page_set_anon_rmap(page, vma, address);
 	if (page_evictable(page, vma))
 		lru_cache_add_lru(page, LRU_ACTIVE_ANON);
@@ -872,7 +880,11 @@ void page_remove_rmap(struct page *page)
 	}
 	if (PageAnon(page)) {
 		mem_cgroup_uncharge_page(page);
-		__dec_zone_page_state(page, NR_ANON_PAGES);
+		if (!PageTransHuge(page))
+			__dec_zone_page_state(page, NR_ANON_PAGES);
+		else
+			__dec_zone_page_state(page,
+					      NR_ANON_TRANSPARENT_HUGEPAGES);
 	} else {
 		__dec_zone_page_state(page, NR_FILE_MAPPED);
 		mem_cgroup_update_file_mapped(page, -1);
diff --git a/mm/vmstat.c b/mm/vmstat.c
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -658,6 +658,9 @@ static const char * const vmstat_text[] 
 	"numa_local",
 	"numa_other",
 #endif
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	"nr_anon_transparent_hugepages",
+#endif
 
 #ifdef CONFIG_VM_EVENT_COUNTERS
 	"pgpgin",

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Re: [PATCH 37 of 67] transparent hugepage vmstat

[Avi Kivity]

On 04/08/2010 04:51 AM, Andrea Arcangeli wrote:
> From: Andrea Arcangeli<aarcange@redhat.com>
>
> Add hugepage stat information to /proc/vmstat and /proc/meminfo.
>
>
> diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
> --- a/fs/proc/meminfo.c
> +++ b/fs/proc/meminfo.c
> @@ -101,6 +101,9 @@ static int meminfo_proc_show(struct seq_
>   #ifdef CONFIG_MEMORY_FAILURE
>   		"HardwareCorrupted: %5lu kB\n"
>   #endif
> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +		"AnonHugePages:  %8lu kB\n"
> +#endif
>    


The original AnonPages should include AnonHugePages, or applications 
that are unaware of AnonHugePages will see an unexplained drop in AnonPages.

-- 
error compiling committee.c: too many arguments to function

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[PATCH 38 of 67] khugepaged

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Add khugepaged to relocate fragmented pages into hugepages if new hugepages
become available. (this is indipendent of the defrag logic that will have to
make new hugepages available)

The fundamental reason why khugepaged is unavoidable, is that some
memory can be fragmented and not everything can be relocated. So when
a virtual machine quits and releases gigabytes of hugepages, we want
to use those freely available hugepages to create huge-pmd in the
other virtual machines that may be running on fragmented memory, to
maximize the CPU efficiency at all times. The scan is slow, it takes
nearly zero cpu time, except when it copies data (in which case it
means we definitely want to pay for that cpu time) so it seems a good
tradeoff.

In addition to the hugepages being released by other process releasing memory,
we have the strong suspicion that the performance impact of potentially
defragmenting hugepages during or before each page fault could lead to more
performance inconsistency than allocating small pages at first and having them
collapsed into large pages later... if they prove themselfs to be long lived
mappings (khugepaged scan is slow so short lived mappings have low probability
to run into khugepaged if compared to long lived mappings).

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -23,8 +23,11 @@ extern int zap_huge_pmd(struct mmu_gathe
 enum transparent_hugepage_flag {
 	TRANSPARENT_HUGEPAGE_FLAG,
 	TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+	TRANSPARENT_HUGEPAGE_KHUGEPAGED_FLAG,
+	TRANSPARENT_HUGEPAGE_KHUGEPAGED_REQ_MADV_FLAG,
 	TRANSPARENT_HUGEPAGE_DEFRAG_FLAG,
 	TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG,
+	TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG,
 #ifdef CONFIG_DEBUG_VM
 	TRANSPARENT_HUGEPAGE_DEBUG_COW_FLAG,
 #endif
diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h
new file mode 100644
--- /dev/null
+++ b/include/linux/khugepaged.h
@@ -0,0 +1,66 @@
+#ifndef _LINUX_KHUGEPAGED_H
+#define _LINUX_KHUGEPAGED_H
+
+#include <linux/sched.h> /* MMF_VM_HUGEPAGE */
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+extern int __khugepaged_enter(struct mm_struct *mm);
+extern void __khugepaged_exit(struct mm_struct *mm);
+extern int khugepaged_enter_vma_merge(struct vm_area_struct *vma);
+
+#define khugepaged_enabled()					       \
+	(transparent_hugepage_flags &				       \
+	 ((1<<TRANSPARENT_HUGEPAGE_KHUGEPAGED_FLAG) |		       \
+	  (1<<TRANSPARENT_HUGEPAGE_KHUGEPAGED_REQ_MADV_FLAG)))
+#define khugepaged_always()				\
+	(transparent_hugepage_flags &			\
+	 (1<<TRANSPARENT_HUGEPAGE_KHUGEPAGED_FLAG))
+#define khugepaged_req_madv()					\
+	(transparent_hugepage_flags &				\
+	 (1<<TRANSPARENT_HUGEPAGE_KHUGEPAGED_REQ_MADV_FLAG))
+#define khugepaged_defrag()					\
+	(transparent_hugepage_flags &				\
+	 (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG))
+
+static inline int khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
+{
+	if (test_bit(MMF_VM_HUGEPAGE, &oldmm->flags))
+		return __khugepaged_enter(mm);
+	return 0;
+}
+
+static inline void khugepaged_exit(struct mm_struct *mm)
+{
+	if (test_bit(MMF_VM_HUGEPAGE, &mm->flags))
+		__khugepaged_exit(mm);
+}
+
+static inline int khugepaged_enter(struct vm_area_struct *vma)
+{
+	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags))
+		if (khugepaged_always() ||
+		    (khugepaged_req_madv() &&
+		     vma->vm_flags & VM_HUGEPAGE))
+			if (__khugepaged_enter(vma->vm_mm))
+				return -ENOMEM;
+	return 0;
+}
+#else /* CONFIG_TRANSPARENT_HUGEPAGE */
+static inline int khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm)
+{
+	return 0;
+}
+static inline void khugepaged_exit(struct mm_struct *mm)
+{
+}
+static inline int khugepaged_enter(struct vm_area_struct *vma)
+{
+	return 0;
+}
+static inline int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
+{
+	return 0;
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
+#endif /* _LINUX_KHUGEPAGED_H */
diff --git a/include/linux/sched.h b/include/linux/sched.h
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -436,6 +436,7 @@ extern int get_dumpable(struct mm_struct
 #endif
 					/* leave room for more dump flags */
 #define MMF_VM_MERGEABLE	16	/* KSM may merge identical pages */
+#define MMF_VM_HUGEPAGE		17	/* set when VM_HUGEPAGE is set on vma */
 
 #define MMF_INIT_MASK		(MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK)
 
diff --git a/kernel/fork.c b/kernel/fork.c
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -65,6 +65,7 @@
 #include <linux/perf_event.h>
 #include <linux/posix-timers.h>
 #include <linux/user-return-notifier.h>
+#include <linux/khugepaged.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -314,6 +315,9 @@ static int dup_mmap(struct mm_struct *mm
 	retval = ksm_fork(mm, oldmm);
 	if (retval)
 		goto out;
+	retval = khugepaged_fork(mm, oldmm);
+	if (retval)
+		goto out;
 
 	for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
 		struct file *file;
@@ -526,6 +530,7 @@ void mmput(struct mm_struct *mm)
 	if (atomic_dec_and_test(&mm->mm_users)) {
 		exit_aio(mm);
 		ksm_exit(mm);
+		khugepaged_exit(mm); /* must run before exit_mmap */
 		exit_mmap(mm);
 		set_mm_exe_file(mm, NULL);
 		if (!list_empty(&mm->mmlist)) {
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -12,14 +12,124 @@
 #include <linux/mmu_notifier.h>
 #include <linux/rmap.h>
 #include <linux/swap.h>
+#include <linux/mm_inline.h>
+#include <linux/kthread.h>
+#include <linux/khugepaged.h>
 #include <asm/tlb.h>
 #include <asm/pgalloc.h>
 #include "internal.h"
 
+/*
+ * By default transparent hugepage support is enabled for all mappings
+ * and khugepaged scans all mappings. Defrag is only invoked by
+ * khugepaged hugepage allocations and by page faults inside
+ * MADV_HUGEPAGE regions to avoid the risk of slowing down short lived
+ * allocations.
+ */
 unsigned long transparent_hugepage_flags __read_mostly =
-	(1<<TRANSPARENT_HUGEPAGE_FLAG);
+	(1<<TRANSPARENT_HUGEPAGE_FLAG)|
+	(1<<TRANSPARENT_HUGEPAGE_KHUGEPAGED_FLAG)|
+	(1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
+
+/* default scan 8*512 pte (or vmas) every 30 second */
+static unsigned int khugepaged_pages_to_scan __read_mostly = HPAGE_PMD_NR*8;
+static unsigned int khugepaged_pages_collapsed;
+static unsigned int khugepaged_full_scans;
+static unsigned int khugepaged_scan_sleep_millisecs __read_mostly = 10000;
+/* during fragmentation poll the hugepage allocator once every minute */
+static unsigned int khugepaged_alloc_sleep_millisecs __read_mostly = 60000;
+static struct task_struct *khugepaged_thread __read_mostly;
+static DEFINE_MUTEX(khugepaged_mutex);
+static DEFINE_SPINLOCK(khugepaged_mm_lock);
+static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
+/*
+ * default collapse hugepages if there is at least one pte mapped like
+ * it would have happened if the vma was large enough during page
+ * fault.
+ */
+static unsigned int khugepaged_max_ptes_none __read_mostly = HPAGE_PMD_NR-1;
+
+static int khugepaged(void *none);
+static int mm_slots_hash_init(void);
+static int khugepaged_slab_init(void);
+static void khugepaged_slab_free(void);
+
+#define MM_SLOTS_HASH_HEADS 1024
+static struct hlist_head *mm_slots_hash __read_mostly;
+static struct kmem_cache *mm_slot_cache __read_mostly;
+
+/**
+ * struct mm_slot - hash lookup from mm to mm_slot
+ * @hash: hash collision list
+ * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
+ * @mm: the mm that this information is valid for
+ */
+struct mm_slot {
+	struct hlist_node hash;
+	struct list_head mm_node;
+	struct mm_struct *mm;
+};
+
+/**
+ * struct khugepaged_scan - cursor for scanning
+ * @mm_head: the head of the mm list to scan
+ * @mm_slot: the current mm_slot we are scanning
+ * @address: the next address inside that to be scanned
+ *
+ * There is only the one khugepaged_scan instance of this cursor structure.
+ */
+struct khugepaged_scan {
+	struct list_head mm_head;
+	struct mm_slot *mm_slot;
+	unsigned long address;
+} khugepaged_scan = {
+	.mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
+};
+
+static int start_khugepaged(void)
+{
+	int err = 0;
+	if (khugepaged_enabled()) {
+		int wakeup;
+		if (unlikely(!mm_slot_cache || !mm_slots_hash)) {
+			err = -ENOMEM;
+			goto out;
+		}
+		mutex_lock(&khugepaged_mutex);
+		if (!khugepaged_thread)
+			khugepaged_thread = kthread_run(khugepaged, NULL,
+							"khugepaged");
+		if (unlikely(IS_ERR(khugepaged_thread))) {
+			clear_bit(TRANSPARENT_HUGEPAGE_KHUGEPAGED_FLAG,
+				  &transparent_hugepage_flags);
+			clear_bit(TRANSPARENT_HUGEPAGE_KHUGEPAGED_REQ_MADV_FLAG,
+				  &transparent_hugepage_flags);
+			printk(KERN_ERR
+			       "khugepaged: kthread_run(khugepaged) failed\n");
+			err = PTR_ERR(khugepaged_thread);
+			khugepaged_thread = NULL;
+		}
+		wakeup = !list_empty(&khugepaged_scan.mm_head);
+		mutex_unlock(&khugepaged_mutex);
+		if (wakeup)
+			wake_up_interruptible(&khugepaged_wait);
+	} else
+		/* wakeup to exit */
+		wake_up_interruptible(&khugepaged_wait);
+out:
+	return err;
+}
 
 #ifdef CONFIG_SYSFS
+
+static void wakeup_khugepaged(void)
+{
+	mutex_lock(&khugepaged_mutex);
+	if (khugepaged_thread)
+		wake_up_process(khugepaged_thread);
+	mutex_unlock(&khugepaged_mutex);
+}
+
 static ssize_t double_flag_show(struct kobject *kobj,
 				struct kobj_attribute *attr, char *buf,
 				enum transparent_hugepage_flag enabled,
@@ -153,20 +263,240 @@ static struct attribute *hugepage_attr[]
 
 static struct attribute_group hugepage_attr_group = {
 	.attrs = hugepage_attr,
-	.name = "transparent_hugepage",
+};
+
+static ssize_t scan_sleep_millisecs_show(struct kobject *kobj,
+					 struct kobj_attribute *attr,
+					 char *buf)
+{
+	return sprintf(buf, "%u\n", khugepaged_scan_sleep_millisecs);
+}
+
+static ssize_t scan_sleep_millisecs_store(struct kobject *kobj,
+					  struct kobj_attribute *attr,
+					  const char *buf, size_t count)
+{
+	unsigned long msecs;
+	int err;
+
+	err = strict_strtoul(buf, 10, &msecs);
+	if (err || msecs > UINT_MAX)
+		return -EINVAL;
+
+	khugepaged_scan_sleep_millisecs = msecs;
+	wakeup_khugepaged();
+
+	return count;
+}
+static struct kobj_attribute scan_sleep_millisecs_attr =
+	__ATTR(scan_sleep_millisecs, 0644, scan_sleep_millisecs_show,
+	       scan_sleep_millisecs_store);
+
+static ssize_t alloc_sleep_millisecs_show(struct kobject *kobj,
+					  struct kobj_attribute *attr,
+					  char *buf)
+{
+	return sprintf(buf, "%u\n", khugepaged_alloc_sleep_millisecs);
+}
+
+static ssize_t alloc_sleep_millisecs_store(struct kobject *kobj,
+					   struct kobj_attribute *attr,
+					   const char *buf, size_t count)
+{
+	unsigned long msecs;
+	int err;
+
+	err = strict_strtoul(buf, 10, &msecs);
+	if (err || msecs > UINT_MAX)
+		return -EINVAL;
+
+	khugepaged_alloc_sleep_millisecs = msecs;
+	wakeup_khugepaged();
+
+	return count;
+}
+static struct kobj_attribute alloc_sleep_millisecs_attr =
+	__ATTR(alloc_sleep_millisecs, 0644, alloc_sleep_millisecs_show,
+	       alloc_sleep_millisecs_store);
+
+static ssize_t pages_to_scan_show(struct kobject *kobj,
+				  struct kobj_attribute *attr,
+				  char *buf)
+{
+	return sprintf(buf, "%u\n", khugepaged_pages_to_scan);
+}
+static ssize_t pages_to_scan_store(struct kobject *kobj,
+				   struct kobj_attribute *attr,
+				   const char *buf, size_t count)
+{
+	int err;
+	unsigned long pages;
+
+	err = strict_strtoul(buf, 10, &pages);
+	if (err || !pages || pages > UINT_MAX)
+		return -EINVAL;
+
+	khugepaged_pages_to_scan = pages;
+
+	return count;
+}
+static struct kobj_attribute pages_to_scan_attr =
+	__ATTR(pages_to_scan, 0644, pages_to_scan_show,
+	       pages_to_scan_store);
+
+static ssize_t pages_collapsed_show(struct kobject *kobj,
+				    struct kobj_attribute *attr,
+				    char *buf)
+{
+	return sprintf(buf, "%u\n", khugepaged_pages_collapsed);
+}
+static struct kobj_attribute pages_collapsed_attr =
+	__ATTR_RO(pages_collapsed);
+
+static ssize_t full_scans_show(struct kobject *kobj,
+			       struct kobj_attribute *attr,
+			       char *buf)
+{
+	return sprintf(buf, "%u\n", khugepaged_full_scans);
+}
+static struct kobj_attribute full_scans_attr =
+	__ATTR_RO(full_scans);
+
+static ssize_t khugepaged_enabled_show(struct kobject *kobj,
+				       struct kobj_attribute *attr, char *buf)
+{
+	return double_flag_show(kobj, attr, buf,
+				TRANSPARENT_HUGEPAGE_KHUGEPAGED_FLAG,
+				TRANSPARENT_HUGEPAGE_KHUGEPAGED_REQ_MADV_FLAG);
+}
+static ssize_t khugepaged_enabled_store(struct kobject *kobj,
+					struct kobj_attribute *attr,
+					const char *buf, size_t count)
+{
+	ssize_t ret;
+
+	ret = double_flag_store(kobj, attr, buf, count,
+				TRANSPARENT_HUGEPAGE_KHUGEPAGED_FLAG,
+				TRANSPARENT_HUGEPAGE_KHUGEPAGED_REQ_MADV_FLAG);
+	if (ret > 0) {
+		int err = start_khugepaged();
+		if (err)
+			ret = err;
+	}
+	return ret;
+}
+static struct kobj_attribute khugepaged_enabled_attr =
+	__ATTR(enabled, 0644, khugepaged_enabled_show,
+	       khugepaged_enabled_store);
+
+static ssize_t khugepaged_defrag_show(struct kobject *kobj,
+				      struct kobj_attribute *attr, char *buf)
+{
+	return single_flag_show(kobj, attr, buf,
+				TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
+}
+static ssize_t khugepaged_defrag_store(struct kobject *kobj,
+				       struct kobj_attribute *attr,
+				       const char *buf, size_t count)
+{
+	return single_flag_store(kobj, attr, buf, count,
+				 TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
+}
+static struct kobj_attribute khugepaged_defrag_attr =
+	__ATTR(defrag, 0644, khugepaged_defrag_show,
+	       khugepaged_defrag_store);
+
+/*
+ * max_ptes_none controls if khugepaged should collapse hugepages over
+ * any unmapped ptes in turn potentially increasing the memory
+ * footprint of the vmas. When max_ptes_none is 0 khugepaged will not
+ * reduce the available free memory in the system as it
+ * runs. Increasing max_ptes_none will instead potentially reduce the
+ * free memory in the system during the khugepaged scan.
+ */
+static ssize_t khugepaged_max_ptes_none_show(struct kobject *kobj,
+					     struct kobj_attribute *attr,
+					     char *buf)
+{
+	return sprintf(buf, "%u\n", khugepaged_max_ptes_none);
+}
+static ssize_t khugepaged_max_ptes_none_store(struct kobject *kobj,
+					      struct kobj_attribute *attr,
+					      const char *buf, size_t count)
+{
+	int err;
+	unsigned long max_ptes_none;
+
+	err = strict_strtoul(buf, 10, &max_ptes_none);
+	if (err || max_ptes_none > HPAGE_PMD_NR-1)
+		return -EINVAL;
+
+	khugepaged_max_ptes_none = max_ptes_none;
+
+	return count;
+}
+static struct kobj_attribute khugepaged_max_ptes_none_attr =
+	__ATTR(max_ptes_none, 0644, khugepaged_max_ptes_none_show,
+	       khugepaged_max_ptes_none_store);
+
+static struct attribute *khugepaged_attr[] = {
+	&khugepaged_enabled_attr.attr,
+	&khugepaged_defrag_attr.attr,
+	&khugepaged_max_ptes_none_attr.attr,
+	&pages_to_scan_attr.attr,
+	&pages_collapsed_attr.attr,
+	&full_scans_attr.attr,
+	&scan_sleep_millisecs_attr.attr,
+	&alloc_sleep_millisecs_attr.attr,
+	NULL,
+};
+
+static struct attribute_group khugepaged_attr_group = {
+	.attrs = khugepaged_attr,
+	.name = "khugepaged",
 };
 #endif /* CONFIG_SYSFS */
 
 static int __init hugepage_init(void)
 {
+	int err;
 #ifdef CONFIG_SYSFS
-	int err;
+	static struct kobject *hugepage_kobj;
 
-	err = sysfs_create_group(mm_kobj, &hugepage_attr_group);
+	err = -ENOMEM;
+	hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
+	if (unlikely(!hugepage_kobj)) {
+		printk(KERN_ERR "hugepage: failed kobject create\n");
+		goto out;
+	}
+
+	err = sysfs_create_group(hugepage_kobj, &hugepage_attr_group);
+	if (err) {
+		printk(KERN_ERR "hugepage: failed register hugeage group\n");
+		goto out;
+	}
+
+	err = sysfs_create_group(hugepage_kobj, &khugepaged_attr_group);
+	if (err) {
+		printk(KERN_ERR "hugepage: failed register hugeage group\n");
+		goto out;
+	}
+#endif
+
+	err = khugepaged_slab_init();
 	if (err)
-		printk(KERN_ERR "hugepage: register sysfs failed\n");
-#endif
-	return 0;
+		goto out;
+
+	err = mm_slots_hash_init();
+	if (err) {
+		khugepaged_slab_free();
+		goto out;
+	}
+
+	start_khugepaged();
+
+out:
+	return err;
 }
 module_init(hugepage_init)
 
@@ -183,6 +513,15 @@ static int __init setup_transparent_huge
 		       transparent_hugepage_flags);
 		transparent_hugepage_flags = 0;
 	}
+	if (test_bit(TRANSPARENT_HUGEPAGE_KHUGEPAGED_FLAG,
+		     &transparent_hugepage_flags) &&
+	    test_bit(TRANSPARENT_HUGEPAGE_KHUGEPAGED_REQ_MADV_FLAG,
+		     &transparent_hugepage_flags)) {
+		printk(KERN_WARNING
+		       "transparent_hugepage=%lu invalid parameter, disabling",
+		       transparent_hugepage_flags);
+		transparent_hugepage_flags = 0;
+	}
 	return 1;
 }
 __setup("transparent_hugepage=", setup_transparent_hugepage);
@@ -277,6 +616,8 @@ int do_huge_pmd_anonymous_page(struct mm
 	if (haddr >= vma->vm_start && haddr + HPAGE_PMD_SIZE <= vma->vm_end) {
 		if (unlikely(anon_vma_prepare(vma)))
 			return VM_FAULT_OOM;
+		if (unlikely(khugepaged_enter(vma)))
+			return VM_FAULT_OOM;
 		page = alloc_hugepage(transparent_hugepage_defrag(vma));
 		if (unlikely(!page))
 			goto out;
@@ -881,6 +1222,755 @@ int hugepage_madvise(unsigned long *vm_f
 	return 0;
 }
 
+static int __init khugepaged_slab_init(void)
+{
+	mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
+					  sizeof(struct mm_slot),
+					  __alignof__(struct mm_slot), 0, NULL);
+	if (!mm_slot_cache)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void __init khugepaged_slab_free(void)
+{
+	kmem_cache_destroy(mm_slot_cache);
+	mm_slot_cache = NULL;
+}
+
+static inline struct mm_slot *alloc_mm_slot(void)
+{
+	if (!mm_slot_cache)	/* initialization failed */
+		return NULL;
+	return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
+}
+
+static inline void free_mm_slot(struct mm_slot *mm_slot)
+{
+	kmem_cache_free(mm_slot_cache, mm_slot);
+}
+
+static int __init mm_slots_hash_init(void)
+{
+	mm_slots_hash = kzalloc(MM_SLOTS_HASH_HEADS * sizeof(struct hlist_head),
+				GFP_KERNEL);
+	if (!mm_slots_hash)
+		return -ENOMEM;
+	return 0;
+}
+
+#if 0
+static void __init mm_slots_hash_free(void)
+{
+	kfree(mm_slots_hash);
+	mm_slots_hash = NULL;
+}
+#endif
+
+static struct mm_slot *get_mm_slot(struct mm_struct *mm)
+{
+	struct mm_slot *mm_slot;
+	struct hlist_head *bucket;
+	struct hlist_node *node;
+
+	bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
+				% MM_SLOTS_HASH_HEADS];
+	hlist_for_each_entry(mm_slot, node, bucket, hash) {
+		if (mm == mm_slot->mm)
+			return mm_slot;
+	}
+	return NULL;
+}
+
+static void insert_to_mm_slots_hash(struct mm_struct *mm,
+				    struct mm_slot *mm_slot)
+{
+	struct hlist_head *bucket;
+
+	bucket = &mm_slots_hash[((unsigned long)mm / sizeof(struct mm_struct))
+				% MM_SLOTS_HASH_HEADS];
+	mm_slot->mm = mm;
+	hlist_add_head(&mm_slot->hash, bucket);
+}
+
+static inline int khugepaged_test_exit(struct mm_struct *mm)
+{
+	return atomic_read(&mm->mm_users) == 0;
+}
+
+int __khugepaged_enter(struct mm_struct *mm)
+{
+	struct mm_slot *mm_slot;
+	int wakeup;
+
+	mm_slot = alloc_mm_slot();
+	if (!mm_slot)
+		return -ENOMEM;
+
+	/* __khugepaged_exit() must not run from under us */
+	VM_BUG_ON(khugepaged_test_exit(mm));
+	if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
+		free_mm_slot(mm_slot);
+		return 0;
+	}
+
+	spin_lock(&khugepaged_mm_lock);
+	insert_to_mm_slots_hash(mm, mm_slot);
+	/*
+	 * Insert just behind the scanning cursor, to let the area settle
+	 * down a little.
+	 */
+	wakeup = list_empty(&khugepaged_scan.mm_head);
+	list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
+	spin_unlock(&khugepaged_mm_lock);
+
+	atomic_inc(&mm->mm_count);
+	if (wakeup)
+		wake_up_interruptible(&khugepaged_wait);
+
+	return 0;
+}
+
+int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
+{
+	unsigned long hstart, hend;
+	if (!vma->anon_vma)
+		/*
+		 * Not yet faulted in so we will register later in the
+		 * page fault if needed.
+		 */
+		return 0;
+	if (vma->vm_file || vma->vm_ops)
+		/* khugepaged not yet working on file or special mappings */
+		return 0;
+	VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma));
+	hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
+	hend = vma->vm_end & HPAGE_PMD_MASK;
+	if (hstart < hend)
+		return khugepaged_enter(vma);
+	return 0;
+}
+
+void __khugepaged_exit(struct mm_struct *mm)
+{
+	struct mm_slot *mm_slot;
+	int free = 0;
+
+	spin_lock(&khugepaged_mm_lock);
+	mm_slot = get_mm_slot(mm);
+	if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
+		hlist_del(&mm_slot->hash);
+		list_del(&mm_slot->mm_node);
+		free = 1;
+	}
+
+	if (free) {
+		spin_unlock(&khugepaged_mm_lock);
+		clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
+		free_mm_slot(mm_slot);
+		mmdrop(mm);
+	} else if (mm_slot) {
+		spin_unlock(&khugepaged_mm_lock);
+		/*
+		 * This is required to serialize against
+		 * khugepaged_test_exit() (which is guaranteed to run
+		 * under mmap sem read mode). Stop here (after we
+		 * return all pagetables will be destroyed) until
+		 * khugepaged has finished working on the pagetables
+		 * under the mmap_sem.
+		 */
+		down_write(&mm->mmap_sem);
+		up_write(&mm->mmap_sem);
+	} else
+		spin_unlock(&khugepaged_mm_lock);
+}
+
+static void release_pte_page(struct page *page)
+{
+	/* 0 stands for page_is_file_cache(page) == false */
+	dec_zone_page_state(page, NR_ISOLATED_ANON + 0);
+	unlock_page(page);
+	putback_lru_page(page);
+}
+
+static void release_pte_pages(pte_t *pte, pte_t *_pte)
+{
+	while (--_pte >= pte) {
+		pte_t pteval = *_pte;
+		if (!pte_none(pteval))
+			release_pte_page(pte_page(pteval));
+	}
+}
+
+static void release_all_pte_pages(pte_t *pte)
+{
+	release_pte_pages(pte, pte + HPAGE_PMD_NR);
+}
+
+static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
+					unsigned long address,
+					pte_t *pte)
+{
+	struct page *page;
+	pte_t *_pte;
+	int referenced = 0, isolated = 0, none = 0;
+	for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
+	     _pte++, address += PAGE_SIZE) {
+		pte_t pteval = *_pte;
+		if (pte_none(pteval)) {
+			if (++none <= khugepaged_max_ptes_none)
+				continue;
+			else {
+				release_pte_pages(pte, _pte);
+				goto out;
+			}
+		}
+		if (!pte_present(pteval) || !pte_write(pteval)) {
+			release_pte_pages(pte, _pte);
+			goto out;
+		}
+		page = vm_normal_page(vma, address, pteval);
+		if (unlikely(!page)) {
+			release_pte_pages(pte, _pte);
+			goto out;
+		}
+		VM_BUG_ON(PageCompound(page));
+		BUG_ON(!PageAnon(page));
+		VM_BUG_ON(!PageSwapBacked(page));
+
+		/* cannot use mapcount: can't collapse if there's a gup pin */
+		if (page_count(page) != 1) {
+			release_pte_pages(pte, _pte);
+			goto out;
+		}
+		/*
+		 * We can do it before isolate_lru_page because the
+		 * page can't be freed from under us. NOTE: PG_lock
+		 * is needed to serialize against split_huge_page
+		 * when invoked from the VM.
+		 */
+		if (!trylock_page(page)) {
+			release_pte_pages(pte, _pte);
+			goto out;
+		}
+		/*
+		 * Isolate the page to avoid collapsing an hugepage
+		 * currently in use by the VM.
+		 */
+		if (isolate_lru_page(page)) {
+			unlock_page(page);
+			release_pte_pages(pte, _pte);
+			goto out;
+		}
+		/* 0 stands for page_is_file_cache(page) == false */
+		inc_zone_page_state(page, NR_ISOLATED_ANON + 0);
+		VM_BUG_ON(!PageLocked(page));
+		VM_BUG_ON(PageLRU(page));
+
+		/* If there is no mapped pte young don't collapse the page */
+		if (pte_young(pteval))
+			referenced = 1;
+	}
+	if (unlikely(!referenced))
+		release_all_pte_pages(pte);
+	else
+		isolated = 1;
+out:
+	return isolated;
+}
+
+static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
+				      struct vm_area_struct *vma,
+				      unsigned long address,
+				      spinlock_t *ptl)
+{
+	pte_t *_pte;
+	for (_pte = pte; _pte < pte+HPAGE_PMD_NR; _pte++) {
+		pte_t pteval = *_pte;
+		struct page *src_page;
+
+		if (pte_none(pteval)) {
+			clear_user_highpage(page, address);
+			add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
+		} else {
+			src_page = pte_page(pteval);
+			copy_user_highpage(page, src_page, address, vma);
+			VM_BUG_ON(page_mapcount(src_page) != 1);
+			VM_BUG_ON(page_count(src_page) != 2);
+			release_pte_page(src_page);
+			/*
+			 * ptl mostly unnecessary, but preempt has to
+			 * be disabled to update the per-cpu stats
+			 * inside page_remove_rmap().
+			 */
+			spin_lock(ptl);
+			/*
+			 * paravirt calls inside pte_clear here are
+			 * superfluous.
+			 */
+			pte_clear(vma->vm_mm, address, _pte);
+			page_remove_rmap(src_page);
+			spin_unlock(ptl);
+			free_page_and_swap_cache(src_page);
+		}
+
+		address += PAGE_SIZE;
+		page++;
+	}
+}
+
+static void collapse_huge_page(struct mm_struct *mm,
+			       unsigned long address,
+			       struct page **hpage)
+{
+	struct vm_area_struct *vma;
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd, _pmd;
+	pte_t *pte;
+	pgtable_t pgtable;
+	struct page *new_page;
+	spinlock_t *ptl;
+	int isolated;
+	unsigned long hstart, hend;
+
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+	VM_BUG_ON(!*hpage);
+
+	/*
+	 * Prevent all access to pagetables with the exception of
+	 * gup_fast later hanlded by the ptep_clear_flush and the VM
+	 * handled by the anon_vma lock + PG_lock.
+	 */
+	down_write(&mm->mmap_sem);
+	if (unlikely(khugepaged_test_exit(mm)))
+		goto out;
+
+	vma = find_vma(mm, address);
+	hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
+	hend = vma->vm_end & HPAGE_PMD_MASK;
+	if (address < hstart || address + HPAGE_PMD_SIZE > hend)
+		goto out;
+
+	if (!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always())
+		goto out;
+
+	/* VM_PFNMAP vmas may have vm_ops null but vm_file set */
+	if (!vma->anon_vma || vma->vm_ops || vma->vm_file)
+		goto out;
+	VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma));
+
+	pgd = pgd_offset(mm, address);
+	if (!pgd_present(*pgd))
+		goto out;
+
+	pud = pud_offset(pgd, address);
+	if (!pud_present(*pud))
+		goto out;
+
+	pmd = pmd_offset(pud, address);
+	/* pmd can't go away or become huge under us */
+	if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
+		goto out;
+
+	new_page = *hpage;
+	if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)))
+		goto out;
+
+	/*
+	 * Stop anon_vma rmap pagetable access. vma->anon_vma->lock is
+	 * enough for now (we don't need to check each anon_vma
+	 * pointed by each page->mapping) because collapse_huge_page
+	 * only works on not-shared anon pages (that are guaranteed to
+	 * belong to vma->anon_vma).
+	 */
+	spin_lock(&vma->anon_vma->lock);
+
+	pte = pte_offset_map(pmd, address);
+	ptl = pte_lockptr(mm, pmd);
+
+	spin_lock(&mm->page_table_lock); /* probably unnecessary */
+	/*
+	 * After this gup_fast can't run anymore. This also removes
+	 * any huge TLB entry from the CPU so we won't allow
+	 * huge and small TLB entries for the same virtual address
+	 * to avoid the risk of CPU bugs in that area.
+	 */
+	_pmd = pmdp_clear_flush_notify(vma, address, pmd);
+	spin_unlock(&mm->page_table_lock);
+
+	spin_lock(ptl);
+	isolated = __collapse_huge_page_isolate(vma, address, pte);
+	spin_unlock(ptl);
+	pte_unmap(pte);
+
+	if (unlikely(!isolated)) {
+		spin_lock(&mm->page_table_lock);
+		BUG_ON(!pmd_none(*pmd));
+		set_pmd_at(mm, address, pmd, _pmd);
+		spin_unlock(&mm->page_table_lock);
+		spin_unlock(&vma->anon_vma->lock);
+		mem_cgroup_uncharge_page(new_page);
+		goto out;
+	}
+
+	/*
+	 * All pages are isolated and locked so anon_vma rmap
+	 * can't run anymore.
+	 */
+	spin_unlock(&vma->anon_vma->lock);
+
+	__collapse_huge_page_copy(pte, new_page, vma, address, ptl);
+	__SetPageUptodate(new_page);
+	pgtable = pmd_pgtable(_pmd);
+	VM_BUG_ON(page_count(pgtable) != 1);
+	VM_BUG_ON(page_mapcount(pgtable) != 0);
+
+	_pmd = mk_pmd(new_page, vma->vm_page_prot);
+	_pmd = maybe_pmd_mkwrite(pmd_mkdirty(_pmd), vma);
+	_pmd = pmd_mkhuge(_pmd);
+
+	/*
+	 * spin_lock() below is not the equivalent of smp_wmb(), so
+	 * this is needed to avoid the copy_huge_page writes to become
+	 * visible after the set_pmd_at() write.
+	 */
+	smp_wmb();
+
+	spin_lock(&mm->page_table_lock);
+	BUG_ON(!pmd_none(*pmd));
+	page_add_new_anon_rmap(new_page, vma, address);
+	set_pmd_at(mm, address, pmd, _pmd);
+	update_mmu_cache(vma, address, entry);
+	prepare_pmd_huge_pte(pgtable, mm);
+	mm->nr_ptes--;
+	spin_unlock(&mm->page_table_lock);
+
+	*hpage = NULL;
+	khugepaged_pages_collapsed++;
+out:
+	up_write(&mm->mmap_sem);
+}
+
+static int khugepaged_scan_pmd(struct mm_struct *mm,
+			       struct vm_area_struct *vma,
+			       unsigned long address,
+			       struct page **hpage)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte, *_pte;
+	int ret = 0, referenced = 0, none = 0;
+	struct page *page;
+	unsigned long _address;
+	spinlock_t *ptl;
+
+	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
+
+	pgd = pgd_offset(mm, address);
+	if (!pgd_present(*pgd))
+		goto out;
+
+	pud = pud_offset(pgd, address);
+	if (!pud_present(*pud))
+		goto out;
+
+	pmd = pmd_offset(pud, address);
+	if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
+		goto out;
+
+	pte = pte_offset_map_lock(mm, pmd, address, &ptl);
+	for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
+	     _pte++, _address += PAGE_SIZE) {
+		pte_t pteval = *_pte;
+		if (pte_none(pteval)) {
+			if (++none <= khugepaged_max_ptes_none)
+				continue;
+			else
+				goto out_unmap;
+		}
+		if (!pte_present(pteval) || !pte_write(pteval))
+			goto out_unmap;
+		page = vm_normal_page(vma, _address, pteval);
+		if (unlikely(!page))
+			goto out_unmap;
+		VM_BUG_ON(PageCompound(page));
+		if (!PageLRU(page) || PageLocked(page) || !PageAnon(page))
+			goto out_unmap;
+		/* cannot use mapcount: can't collapse if there's a gup pin */
+		if (page_count(page) != 1)
+			goto out_unmap;
+		if (pte_young(pteval))
+			referenced = 1;
+	}
+	if (referenced)
+		ret = 1;
+out_unmap:
+	pte_unmap_unlock(pte, ptl);
+	if (ret) {
+		up_read(&mm->mmap_sem);
+		collapse_huge_page(mm, address, hpage);
+	}
+out:
+	return ret;
+}
+
+static void collect_mm_slot(struct mm_slot *mm_slot)
+{
+	struct mm_struct *mm = mm_slot->mm;
+
+	VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock));
+
+	if (khugepaged_test_exit(mm)) {
+		/* free mm_slot */
+		hlist_del(&mm_slot->hash);
+		list_del(&mm_slot->mm_node);
+
+		/*
+		 * Not strictly needed because the mm exited already.
+		 *
+		 * clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
+		 */
+
+		/* khugepaged_mm_lock actually not necessary for the below */
+		free_mm_slot(mm_slot);
+		mmdrop(mm);
+	}
+}
+
+static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
+					    struct page **hpage)
+{
+	struct mm_slot *mm_slot;
+	struct mm_struct *mm;
+	struct vm_area_struct *vma;
+	int progress = 0;
+
+	VM_BUG_ON(!pages);
+	VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock));
+
+	if (khugepaged_scan.mm_slot)
+		mm_slot = khugepaged_scan.mm_slot;
+	else {
+		mm_slot = list_entry(khugepaged_scan.mm_head.next,
+				     struct mm_slot, mm_node);
+		khugepaged_scan.address = 0;
+		khugepaged_scan.mm_slot = mm_slot;
+	}
+	spin_unlock(&khugepaged_mm_lock);
+
+	mm = mm_slot->mm;
+	down_read(&mm->mmap_sem);
+	if (unlikely(khugepaged_test_exit(mm)))
+		vma = NULL;
+	else
+		vma = find_vma(mm, khugepaged_scan.address);
+
+	progress++;
+	for (; vma; vma = vma->vm_next) {
+		unsigned long hstart, hend;
+
+		cond_resched();
+		if (unlikely(khugepaged_test_exit(mm))) {
+			progress++;
+			break;
+		}
+
+		if (!(vma->vm_flags & VM_HUGEPAGE) &&
+		    !khugepaged_always()) {
+			progress++;
+			continue;
+		}
+
+		/* VM_PFNMAP vmas may have vm_ops null but vm_file set */
+		if (!vma->anon_vma || vma->vm_ops || vma->vm_file) {
+			khugepaged_scan.address = vma->vm_end;
+			progress++;
+			continue;
+		}
+		VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma));
+
+		hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
+		hend = vma->vm_end & HPAGE_PMD_MASK;
+		if (hstart >= hend) {
+			progress++;
+			continue;
+		}
+		if (khugepaged_scan.address < hstart)
+			khugepaged_scan.address = hstart;
+		if (khugepaged_scan.address > hend) {
+			khugepaged_scan.address = hend + HPAGE_PMD_SIZE;
+			progress++;
+			continue;
+		}
+		BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
+
+		while (khugepaged_scan.address < hend) {
+			int ret;
+			cond_resched();
+			if (unlikely(khugepaged_test_exit(mm)))
+				goto breakouterloop;
+
+			VM_BUG_ON(khugepaged_scan.address < hstart ||
+				  khugepaged_scan.address + HPAGE_PMD_SIZE >
+				  hend);
+			ret = khugepaged_scan_pmd(mm, vma,
+						  khugepaged_scan.address,
+						  hpage);
+			/* move to next address */
+			khugepaged_scan.address += HPAGE_PMD_SIZE;
+			progress += HPAGE_PMD_NR;
+			if (ret)
+				/* we released mmap_sem so break loop */
+				goto breakouterloop_mmap_sem;
+			if (progress >= pages)
+				goto breakouterloop;
+		}
+	}
+breakouterloop:
+	up_read(&mm->mmap_sem); /* exit_mmap will destroy ptes after this */
+breakouterloop_mmap_sem:
+
+	spin_lock(&khugepaged_mm_lock);
+	BUG_ON(khugepaged_scan.mm_slot != mm_slot);
+	/*
+	 * Release the current mm_slot if this mm is about to die, or
+	 * if we scanned all vmas of this mm.
+	 */
+	if (khugepaged_test_exit(mm) || !vma) {
+		/*
+		 * Make sure that if mm_users is reaching zero while
+		 * khugepaged runs here, khugepaged_exit will find
+		 * mm_slot not pointing to the exiting mm.
+		 */
+		if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
+			khugepaged_scan.mm_slot = list_entry(
+				mm_slot->mm_node.next,
+				struct mm_slot, mm_node);
+			khugepaged_scan.address = 0;
+		} else {
+			khugepaged_scan.mm_slot = NULL;
+			khugepaged_full_scans++;
+		}
+
+		collect_mm_slot(mm_slot);
+	}
+
+	return progress;
+}
+
+static int khugepaged_has_work(void)
+{
+	return !list_empty(&khugepaged_scan.mm_head) &&
+		khugepaged_enabled();
+}
+
+static int khugepaged_wait_event(void)
+{
+	return !list_empty(&khugepaged_scan.mm_head) ||
+		!khugepaged_enabled();
+}
+
+static void khugepaged_do_scan(struct page **hpage)
+{
+	unsigned int progress = 0, pass_through_head = 0;
+	unsigned int pages = khugepaged_pages_to_scan;
+
+	barrier(); /* write khugepaged_pages_to_scan to local stack */
+
+	while (progress < pages) {
+		cond_resched();
+
+		if (!*hpage) {
+			*hpage = alloc_hugepage(khugepaged_defrag());
+			if (unlikely(!*hpage))
+				break;
+		}
+
+		spin_lock(&khugepaged_mm_lock);
+		if (!khugepaged_scan.mm_slot)
+			pass_through_head++;
+		if (khugepaged_has_work() &&
+		    pass_through_head < 2)
+			progress += khugepaged_scan_mm_slot(pages - progress,
+							    hpage);
+		else
+			progress = pages;
+		spin_unlock(&khugepaged_mm_lock);
+	}
+}
+
+static struct page *khugepaged_alloc_hugepage(void)
+{
+	struct page *hpage;
+
+	do {
+		hpage = alloc_hugepage(khugepaged_defrag());
+		if (!hpage)
+			schedule_timeout_interruptible(
+				msecs_to_jiffies(
+					khugepaged_alloc_sleep_millisecs));
+	} while (unlikely(!hpage) &&
+		 likely(khugepaged_enabled()));
+	return hpage;
+}
+
+static void khugepaged_loop(void)
+{
+	struct page *hpage;
+
+	while (likely(khugepaged_enabled())) {
+		hpage = khugepaged_alloc_hugepage();
+		if (unlikely(!hpage))
+			break;
+
+		khugepaged_do_scan(&hpage);
+		if (hpage)
+			put_page(hpage);
+		if (khugepaged_has_work()) {
+			if (!khugepaged_scan_sleep_millisecs)
+				continue;
+			schedule_timeout_interruptible(
+				msecs_to_jiffies(
+					khugepaged_scan_sleep_millisecs));
+		} else if (khugepaged_enabled())
+			wait_event_interruptible(khugepaged_wait,
+						 khugepaged_wait_event());
+	}
+}
+
+static int khugepaged(void *none)
+{
+	struct mm_slot *mm_slot;
+
+	set_user_nice(current, 19);
+
+	for (;;) {
+		BUG_ON(khugepaged_thread != current);
+		khugepaged_loop();
+		BUG_ON(khugepaged_thread != current);
+
+		mutex_lock(&khugepaged_mutex);
+		if (!khugepaged_enabled())
+			break;
+		mutex_unlock(&khugepaged_mutex);
+	}
+
+	spin_lock(&khugepaged_mm_lock);
+	mm_slot = khugepaged_scan.mm_slot;
+	khugepaged_scan.mm_slot = NULL;
+	if (mm_slot)
+		collect_mm_slot(mm_slot);
+	spin_unlock(&khugepaged_mm_lock);
+
+	khugepaged_thread = NULL;
+	mutex_unlock(&khugepaged_mutex);
+
+	return 0;
+}
+
 void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd)
 {
 	struct page *page;
diff --git a/mm/mmap.c b/mm/mmap.c
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -28,6 +28,7 @@
 #include <linux/rmap.h>
 #include <linux/mmu_notifier.h>
 #include <linux/perf_event.h>
+#include <linux/khugepaged.h>
 
 #include <asm/uaccess.h>
 #include <asm/cacheflush.h>
@@ -800,6 +801,7 @@ struct vm_area_struct *vma_merge(struct 
 				end, prev->vm_pgoff, NULL);
 		if (err)
 			return NULL;
+		khugepaged_enter_vma_merge(prev);
 		return prev;
 	}
 
@@ -818,6 +820,7 @@ struct vm_area_struct *vma_merge(struct 
 				next->vm_pgoff - pglen, NULL);
 		if (err)
 			return NULL;
+		khugepaged_enter_vma_merge(area);
 		return area;
 	}
 

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[PATCH 39 of 67] don't leave orhpaned swap cache after ksm merging

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

When swapcache is replaced by a ksm page don't leave orhpaned swap cache.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
---

diff --git a/mm/ksm.c b/mm/ksm.c
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -817,7 +817,7 @@ static int replace_page(struct vm_area_s
 	set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot));
 
 	page_remove_rmap(page);
-	put_page(page);
+	free_page_and_swap_cache(page);
 
 	pte_unmap_unlock(ptep, ptl);
 	err = 0;
@@ -863,7 +863,18 @@ static int try_to_merge_one_page(struct 
 	 * ptes are necessarily already write-protected.  But in either
 	 * case, we need to lock and check page_count is not raised.
 	 */
-	if (write_protect_page(vma, page, &orig_pte) == 0) {
+	err = write_protect_page(vma, page, &orig_pte);
+
+	/*
+	 * After this mapping is wrprotected we don't need further
+	 * checks for PageSwapCache vs page_count unlock_page(page)
+	 * and we rely only on the pte_same() check run under PT lock
+	 * to ensure the pte didn't change since when we wrprotected
+	 * it under PG_lock.
+	 */
+	unlock_page(page);
+
+	if (!err) {
 		if (!kpage) {
 			/*
 			 * While we hold page lock, upgrade page from
@@ -872,22 +883,22 @@ static int try_to_merge_one_page(struct 
 			 */
 			set_page_stable_node(page, NULL);
 			mark_page_accessed(page);
-			err = 0;
 		} else if (pages_identical(page, kpage))
 			err = replace_page(vma, page, kpage, orig_pte);
-	}
+	} else
+		err = -EFAULT;
 
 	if ((vma->vm_flags & VM_LOCKED) && kpage && !err) {
+		lock_page(page);	/* for LRU manipulation */
 		munlock_vma_page(page);
+		unlock_page(page);
 		if (!PageMlocked(kpage)) {
-			unlock_page(page);
 			lock_page(kpage);
 			mlock_vma_page(kpage);
-			page = kpage;		/* for final unlock */
+			unlock_page(kpage);
 		}
 	}
 
-	unlock_page(page);
 out:
 	return err;
 }

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[PATCH 40 of 67] skip transhuge pages in ksm for now

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Skip transhuge pages in ksm for now.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
---

diff --git a/mm/ksm.c b/mm/ksm.c
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -449,7 +449,7 @@ static struct page *get_mergeable_page(s
 	page = follow_page(vma, addr, FOLL_GET);
 	if (!page)
 		goto out;
-	if (PageAnon(page)) {
+	if (PageAnon(page) && !PageTransCompound(page)) {
 		flush_anon_page(vma, page, addr);
 		flush_dcache_page(page);
 	} else {
@@ -1305,7 +1305,19 @@ next_mm:
 			if (ksm_test_exit(mm))
 				break;
 			*page = follow_page(vma, ksm_scan.address, FOLL_GET);
-			if (*page && PageAnon(*page)) {
+			if (!*page) {
+				ksm_scan.address += PAGE_SIZE;
+				cond_resched();
+				continue;
+			}
+			if (PageTransCompound(*page)) {
+				put_page(*page);
+				ksm_scan.address &= HPAGE_PMD_MASK;
+				ksm_scan.address += HPAGE_PMD_SIZE;
+				cond_resched();
+				continue;
+			}
+			if (PageAnon(*page)) {
 				flush_anon_page(vma, *page, ksm_scan.address);
 				flush_dcache_page(*page);
 				rmap_item = get_next_rmap_item(slot,
@@ -1319,8 +1331,7 @@ next_mm:
 				up_read(&mm->mmap_sem);
 				return rmap_item;
 			}
-			if (*page)
-				put_page(*page);
+			put_page(*page);
 			ksm_scan.address += PAGE_SIZE;
 			cond_resched();
 		}

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[PATCH 41 of 67] remove PG_buddy

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

PG_buddy can be converted to _mapcount == -2. So the PG_compound_lock can be
added to page->flags without overflowing (because of the sparse section bits
increasing) with CONFIG_X86_PAE=y and CONFIG_X86_PAT=y. This also has to move
the memory hotplug code from _mapcount to lru.next to avoid any risk of
clashes. We can't use lru.next for PG_buddy removal, but memory hotplug can use
lru.next even more easily than the mapcount instead.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/fs/proc/page.c b/fs/proc/page.c
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -116,15 +116,17 @@ u64 stable_page_flags(struct page *page)
 	if (PageHuge(page))
 		u |= 1 << KPF_HUGE;
 
+	/*
+	 * Caveats on high order pages: page->_count will only be set
+	 * -1 on the head page; SLUB/SLQB do the same for PG_slab;
+	 * SLOB won't set PG_slab at all on compound pages.
+	 */
+	if (PageBuddy(page))
+		u |= 1 << KPF_BUDDY;
+
 	u |= kpf_copy_bit(k, KPF_LOCKED,	PG_locked);
 
-	/*
-	 * Caveats on high order pages:
-	 * PG_buddy will only be set on the head page; SLUB/SLQB do the same
-	 * for PG_slab; SLOB won't set PG_slab at all on compound pages.
-	 */
 	u |= kpf_copy_bit(k, KPF_SLAB,		PG_slab);
-	u |= kpf_copy_bit(k, KPF_BUDDY,		PG_buddy);
 
 	u |= kpf_copy_bit(k, KPF_ERROR,		PG_error);
 	u |= kpf_copy_bit(k, KPF_DIRTY,		PG_dirty);
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -13,12 +13,16 @@ struct mem_section;
 #ifdef CONFIG_MEMORY_HOTPLUG
 
 /*
- * Types for free bootmem.
- * The normal smallest mapcount is -1. Here is smaller value than it.
+ * Types for free bootmem stored in page->lru.next. These have to be in
+ * some random range in unsigned long space for debugging purposes.
  */
-#define SECTION_INFO		(-1 - 1)
-#define MIX_SECTION_INFO	(-1 - 2)
-#define NODE_INFO		(-1 - 3)
+enum {
+	MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE = 12,
+	SECTION_INFO = MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE,
+	MIX_SECTION_INFO,
+	NODE_INFO,
+	MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE = NODE_INFO,
+};
 
 /*
  * pgdat resizing functions
diff --git a/include/linux/mm.h b/include/linux/mm.h
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -358,6 +358,27 @@ static inline void init_page_count(struc
 	atomic_set(&page->_count, 1);
 }
 
+/*
+ * PageBuddy() indicate that the page is free and in the buddy system
+ * (see mm/page_alloc.c).
+ */
+static inline int PageBuddy(struct page *page)
+{
+	return atomic_read(&page->_mapcount) == -2;
+}
+
+static inline void __SetPageBuddy(struct page *page)
+{
+	VM_BUG_ON(atomic_read(&page->_mapcount) != -1);
+	atomic_set(&page->_mapcount, -2);
+}
+
+static inline void __ClearPageBuddy(struct page *page)
+{
+	VM_BUG_ON(!PageBuddy(page));
+	atomic_set(&page->_mapcount, -1);
+}
+
 void put_page(struct page *page);
 void put_pages_list(struct list_head *pages);
 
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -48,9 +48,6 @@
  * struct page (these bits with information) are always mapped into kernel
  * address space...
  *
- * PG_buddy is set to indicate that the page is free and in the buddy system
- * (see mm/page_alloc.c).
- *
  * PG_hwpoison indicates that a page got corrupted in hardware and contains
  * data with incorrect ECC bits that triggered a machine check. Accessing is
  * not safe since it may cause another machine check. Don't touch!
@@ -96,7 +93,6 @@ enum pageflags {
 	PG_swapcache,		/* Swap page: swp_entry_t in private */
 	PG_mappedtodisk,	/* Has blocks allocated on-disk */
 	PG_reclaim,		/* To be reclaimed asap */
-	PG_buddy,		/* Page is free, on buddy lists */
 	PG_swapbacked,		/* Page is backed by RAM/swap */
 	PG_unevictable,		/* Page is "unevictable"  */
 #ifdef CONFIG_MMU
@@ -235,7 +231,6 @@ PAGEFLAG(OwnerPriv1, owner_priv_1) TESTC
  * risky: they bypass page accounting.
  */
 TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback)
-__PAGEFLAG(Buddy, buddy)
 PAGEFLAG(MappedToDisk, mappedtodisk)
 
 /* PG_readahead is only used for file reads; PG_reclaim is only for writes */
@@ -430,7 +425,7 @@ static inline void ClearPageCompound(str
 #define PAGE_FLAGS_CHECK_AT_FREE \
 	(1 << PG_lru	 | 1 << PG_locked    | \
 	 1 << PG_private | 1 << PG_private_2 | \
-	 1 << PG_buddy	 | 1 << PG_writeback | 1 << PG_reserved | \
+	 1 << PG_writeback | 1 << PG_reserved | \
 	 1 << PG_slab	 | 1 << PG_swapcache | 1 << PG_active | \
 	 1 << PG_unevictable | __PG_MLOCKED | __PG_HWPOISON | \
 	 __PG_COMPOUND_LOCK)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -65,9 +65,10 @@ static void release_memory_resource(stru
 
 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
 #ifndef CONFIG_SPARSEMEM_VMEMMAP
-static void get_page_bootmem(unsigned long info,  struct page *page, int type)
+static void get_page_bootmem(unsigned long info,  struct page *page,
+			     unsigned long type)
 {
-	atomic_set(&page->_mapcount, type);
+	page->lru.next = (struct list_head *) type;
 	SetPagePrivate(page);
 	set_page_private(page, info);
 	atomic_inc(&page->_count);
@@ -77,15 +78,16 @@ static void get_page_bootmem(unsigned lo
  * so use __ref to tell modpost not to generate a warning */
 void __ref put_page_bootmem(struct page *page)
 {
-	int type;
+	unsigned long type;
 
-	type = atomic_read(&page->_mapcount);
-	BUG_ON(type >= -1);
+	type = (unsigned long) page->lru.next;
+	BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
+	       type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE);
 
 	if (atomic_dec_return(&page->_count) == 1) {
 		ClearPagePrivate(page);
 		set_page_private(page, 0);
-		reset_page_mapcount(page);
+		INIT_LIST_HEAD(&page->lru);
 		__free_pages_bootmem(page, 0);
 	}
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -426,8 +426,8 @@ __find_combined_index(unsigned long page
  * (c) a page and its buddy have the same order &&
  * (d) a page and its buddy are in the same zone.
  *
- * For recording whether a page is in the buddy system, we use PG_buddy.
- * Setting, clearing, and testing PG_buddy is serialized by zone->lock.
+ * For recording whether a page is in the buddy system, we set ->_mapcount -2.
+ * Setting, clearing, and testing _mapcount -2 is serialized by zone->lock.
  *
  * For recording page's order, we use page_private(page).
  */
@@ -460,7 +460,7 @@ static inline int page_is_buddy(struct p
  * as necessary, plus some accounting needed to play nicely with other
  * parts of the VM system.
  * At each level, we keep a list of pages, which are heads of continuous
- * free pages of length of (1 << order) and marked with PG_buddy. Page's
+ * free pages of length of (1 << order) and marked with _mapcount -2. Page's
  * order is recorded in page_private(page) field.
  * So when we are allocating or freeing one, we can derive the state of the
  * other.  That is, if we allocate a small block, and both were   
@@ -5214,7 +5214,6 @@ static struct trace_print_flags pageflag
 	{1UL << PG_swapcache,		"swapcache"	},
 	{1UL << PG_mappedtodisk,	"mappedtodisk"	},
 	{1UL << PG_reclaim,		"reclaim"	},
-	{1UL << PG_buddy,		"buddy"		},
 	{1UL << PG_swapbacked,		"swapbacked"	},
 	{1UL << PG_unevictable,		"unevictable"	},
 #ifdef CONFIG_MMU
diff --git a/mm/sparse.c b/mm/sparse.c
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -668,10 +668,10 @@ static void __kfree_section_memmap(struc
 static void free_map_bootmem(struct page *page, unsigned long nr_pages)
 {
 	unsigned long maps_section_nr, removing_section_nr, i;
-	int magic;
+	unsigned long magic;
 
 	for (i = 0; i < nr_pages; i++, page++) {
-		magic = atomic_read(&page->_mapcount);
+		magic = (unsigned long) page->lru.next;
 
 		BUG_ON(magic == NODE_INFO);
 

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[PATCH 42 of 67] add x86 32bit support

[Andrea Arcangeli]

From: Johannes Weiner <hannes@cmpxchg.org>

Add support for transparent hugepages to x86 32bit.

Share the same VM_ bitflag for VM_MAPPED_COPY. mm/nommu.c will never support
transparent hugepages.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
---

diff --git a/arch/x86/include/asm/pgtable-2level.h b/arch/x86/include/asm/pgtable-2level.h
--- a/arch/x86/include/asm/pgtable-2level.h
+++ b/arch/x86/include/asm/pgtable-2level.h
@@ -46,6 +46,15 @@ static inline pte_t native_ptep_get_and_
 #define native_ptep_get_and_clear(xp) native_local_ptep_get_and_clear(xp)
 #endif
 
+#ifdef CONFIG_SMP
+static inline pmd_t native_pmdp_get_and_clear(pmd_t *xp)
+{
+	return __pmd(xchg((pmdval_t *)xp, 0));
+}
+#else
+#define native_pmdp_get_and_clear(xp) native_local_pmdp_get_and_clear(xp)
+#endif
+
 /*
  * Bits _PAGE_BIT_PRESENT, _PAGE_BIT_FILE and _PAGE_BIT_PROTNONE are taken,
  * split up the 29 bits of offset into this range:
diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
--- a/arch/x86/include/asm/pgtable-3level.h
+++ b/arch/x86/include/asm/pgtable-3level.h
@@ -104,6 +104,29 @@ static inline pte_t native_ptep_get_and_
 #define native_ptep_get_and_clear(xp) native_local_ptep_get_and_clear(xp)
 #endif
 
+#ifdef CONFIG_SMP
+union split_pmd {
+	struct {
+		u32 pmd_low;
+		u32 pmd_high;
+	};
+	pmd_t pmd;
+};
+static inline pmd_t native_pmdp_get_and_clear(pmd_t *pmdp)
+{
+	union split_pmd res, *orig = (union split_pmd *)pmdp;
+
+	/* xchg acts as a barrier before setting of the high bits */
+	res.pmd_low = xchg(&orig->pmd_low, 0);
+	res.pmd_high = orig->pmd_high;
+	orig->pmd_high = 0;
+
+	return res.pmd;
+}
+#else
+#define native_pmdp_get_and_clear(xp) native_local_pmdp_get_and_clear(xp)
+#endif
+
 /*
  * Bits 0, 6 and 7 are taken in the low part of the pte,
  * put the 32 bits of offset into the high part.
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -95,6 +95,11 @@ static inline int pte_young(pte_t pte)
 	return pte_flags(pte) & _PAGE_ACCESSED;
 }
 
+static inline int pmd_young(pmd_t pmd)
+{
+	return pmd_flags(pmd) & _PAGE_ACCESSED;
+}
+
 static inline int pte_write(pte_t pte)
 {
 	return pte_flags(pte) & _PAGE_RW;
@@ -143,6 +148,18 @@ static inline int pmd_large(pmd_t pte)
 		(_PAGE_PSE | _PAGE_PRESENT);
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline int pmd_trans_splitting(pmd_t pmd)
+{
+	return pmd_val(pmd) & _PAGE_SPLITTING;
+}
+
+static inline int pmd_trans_huge(pmd_t pmd)
+{
+	return pmd_val(pmd) & _PAGE_PSE;
+}
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
 static inline pte_t pte_set_flags(pte_t pte, pteval_t set)
 {
 	pteval_t v = native_pte_val(pte);
@@ -217,6 +234,55 @@ static inline pte_t pte_mkspecial(pte_t 
 	return pte_set_flags(pte, _PAGE_SPECIAL);
 }
 
+static inline pmd_t pmd_set_flags(pmd_t pmd, pmdval_t set)
+{
+	pmdval_t v = native_pmd_val(pmd);
+
+	return __pmd(v | set);
+}
+
+static inline pmd_t pmd_clear_flags(pmd_t pmd, pmdval_t clear)
+{
+	pmdval_t v = native_pmd_val(pmd);
+
+	return __pmd(v & ~clear);
+}
+
+static inline pmd_t pmd_mkold(pmd_t pmd)
+{
+	return pmd_clear_flags(pmd, _PAGE_ACCESSED);
+}
+
+static inline pmd_t pmd_wrprotect(pmd_t pmd)
+{
+	return pmd_clear_flags(pmd, _PAGE_RW);
+}
+
+static inline pmd_t pmd_mkdirty(pmd_t pmd)
+{
+	return pmd_set_flags(pmd, _PAGE_DIRTY);
+}
+
+static inline pmd_t pmd_mkhuge(pmd_t pmd)
+{
+	return pmd_set_flags(pmd, _PAGE_PSE);
+}
+
+static inline pmd_t pmd_mkyoung(pmd_t pmd)
+{
+	return pmd_set_flags(pmd, _PAGE_ACCESSED);
+}
+
+static inline pmd_t pmd_mkwrite(pmd_t pmd)
+{
+	return pmd_set_flags(pmd, _PAGE_RW);
+}
+
+static inline pmd_t pmd_mknotpresent(pmd_t pmd)
+{
+	return pmd_clear_flags(pmd, _PAGE_PRESENT);
+}
+
 /*
  * Mask out unsupported bits in a present pgprot.  Non-present pgprots
  * can use those bits for other purposes, so leave them be.
@@ -525,6 +591,14 @@ static inline pte_t native_local_ptep_ge
 	return res;
 }
 
+static inline pmd_t native_local_pmdp_get_and_clear(pmd_t *pmdp)
+{
+	pmd_t res = *pmdp;
+
+	native_pmd_clear(pmdp);
+	return res;
+}
+
 static inline void native_set_pte_at(struct mm_struct *mm, unsigned long addr,
 				     pte_t *ptep , pte_t pte)
 {
@@ -612,6 +686,49 @@ static inline void ptep_set_wrprotect(st
 	pte_update(mm, addr, ptep);
 }
 
+#define mk_pmd(page, pgprot)   pfn_pmd(page_to_pfn(page), (pgprot))
+
+#define  __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
+extern int pmdp_set_access_flags(struct vm_area_struct *vma,
+				 unsigned long address, pmd_t *pmdp,
+				 pmd_t entry, int dirty);
+
+#define __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG
+extern int pmdp_test_and_clear_young(struct vm_area_struct *vma,
+				     unsigned long addr, pmd_t *pmdp);
+
+#define __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
+extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
+				  unsigned long address, pmd_t *pmdp);
+
+
+#define __HAVE_ARCH_PMDP_SPLITTING_FLUSH
+extern void pmdp_splitting_flush(struct vm_area_struct *vma,
+				 unsigned long addr, pmd_t *pmdp);
+
+#define __HAVE_ARCH_PMD_WRITE
+static inline int pmd_write(pmd_t pmd)
+{
+	return pmd_flags(pmd) & _PAGE_RW;
+}
+
+#define __HAVE_ARCH_PMDP_GET_AND_CLEAR
+static inline pmd_t pmdp_get_and_clear(struct mm_struct *mm, unsigned long addr,
+				       pmd_t *pmdp)
+{
+	pmd_t pmd = native_pmdp_get_and_clear(pmdp);
+	pmd_update(mm, addr, pmdp);
+	return pmd;
+}
+
+#define __HAVE_ARCH_PMDP_SET_WRPROTECT
+static inline void pmdp_set_wrprotect(struct mm_struct *mm,
+				      unsigned long addr, pmd_t *pmdp)
+{
+	clear_bit(_PAGE_BIT_RW, (unsigned long *)pmdp);
+	pmd_update(mm, addr, pmdp);
+}
+
 /*
  * clone_pgd_range(pgd_t *dst, pgd_t *src, int count);
  *
diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -182,115 +182,6 @@ extern void cleanup_highmap(void);
 
 #define __HAVE_ARCH_PTE_SAME
 
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-static inline int pmd_trans_splitting(pmd_t pmd)
-{
-	return pmd_val(pmd) & _PAGE_SPLITTING;
-}
-
-static inline int pmd_trans_huge(pmd_t pmd)
-{
-	return pmd_val(pmd) & _PAGE_PSE;
-}
-#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
-
-#define mk_pmd(page, pgprot)   pfn_pmd(page_to_pfn(page), (pgprot))
-
-#define  __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
-extern int pmdp_set_access_flags(struct vm_area_struct *vma,
-				 unsigned long address, pmd_t *pmdp,
-				 pmd_t entry, int dirty);
-
-#define __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG
-extern int pmdp_test_and_clear_young(struct vm_area_struct *vma,
-				     unsigned long addr, pmd_t *pmdp);
-
-#define __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
-extern int pmdp_clear_flush_young(struct vm_area_struct *vma,
-				  unsigned long address, pmd_t *pmdp);
-
-
-#define __HAVE_ARCH_PMDP_SPLITTING_FLUSH
-extern void pmdp_splitting_flush(struct vm_area_struct *vma,
-				 unsigned long addr, pmd_t *pmdp);
-
-#define __HAVE_ARCH_PMD_WRITE
-static inline int pmd_write(pmd_t pmd)
-{
-	return pmd_flags(pmd) & _PAGE_RW;
-}
-
-#define __HAVE_ARCH_PMDP_GET_AND_CLEAR
-static inline pmd_t pmdp_get_and_clear(struct mm_struct *mm, unsigned long addr,
-				       pmd_t *pmdp)
-{
-	pmd_t pmd = native_pmdp_get_and_clear(pmdp);
-	pmd_update(mm, addr, pmdp);
-	return pmd;
-}
-
-#define __HAVE_ARCH_PMDP_SET_WRPROTECT
-static inline void pmdp_set_wrprotect(struct mm_struct *mm,
-				      unsigned long addr, pmd_t *pmdp)
-{
-	clear_bit(_PAGE_BIT_RW, (unsigned long *)&pmdp->pmd);
-	pmd_update(mm, addr, pmdp);
-}
-
-static inline int pmd_young(pmd_t pmd)
-{
-	return pmd_flags(pmd) & _PAGE_ACCESSED;
-}
-
-static inline pmd_t pmd_set_flags(pmd_t pmd, pmdval_t set)
-{
-	pmdval_t v = native_pmd_val(pmd);
-
-	return native_make_pmd(v | set);
-}
-
-static inline pmd_t pmd_clear_flags(pmd_t pmd, pmdval_t clear)
-{
-	pmdval_t v = native_pmd_val(pmd);
-
-	return native_make_pmd(v & ~clear);
-}
-
-static inline pmd_t pmd_mkold(pmd_t pmd)
-{
-	return pmd_clear_flags(pmd, _PAGE_ACCESSED);
-}
-
-static inline pmd_t pmd_wrprotect(pmd_t pmd)
-{
-	return pmd_clear_flags(pmd, _PAGE_RW);
-}
-
-static inline pmd_t pmd_mkdirty(pmd_t pmd)
-{
-	return pmd_set_flags(pmd, _PAGE_DIRTY);
-}
-
-static inline pmd_t pmd_mkhuge(pmd_t pmd)
-{
-	return pmd_set_flags(pmd, _PAGE_PSE);
-}
-
-static inline pmd_t pmd_mkyoung(pmd_t pmd)
-{
-	return pmd_set_flags(pmd, _PAGE_ACCESSED);
-}
-
-static inline pmd_t pmd_mkwrite(pmd_t pmd)
-{
-	return pmd_set_flags(pmd, _PAGE_RW);
-}
-
-static inline pmd_t pmd_mknotpresent(pmd_t pmd)
-{
-	return pmd_clear_flags(pmd, _PAGE_PRESENT);
-}
-
 #endif /* !__ASSEMBLY__ */
 
 #endif /* _ASM_X86_PGTABLE_64_H */
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -352,7 +352,7 @@ int pmdp_test_and_clear_young(struct vm_
 
 	if (pmd_young(*pmdp))
 		ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
-					 (unsigned long *) &pmdp->pmd);
+					 (unsigned long *)pmdp);
 
 	if (ret)
 		pmd_update(vma->vm_mm, addr, pmdp);
@@ -394,7 +394,7 @@ void pmdp_splitting_flush(struct vm_area
 	int set;
 	VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 	set = !test_and_set_bit(_PAGE_BIT_SPLITTING,
-				(unsigned long *)&pmdp->pmd);
+				(unsigned long *)pmdp);
 	if (set) {
 		pmd_update(vma->vm_mm, address, pmdp);
 		/* need tlb flush only to serialize against gup-fast */
diff --git a/include/linux/mm.h b/include/linux/mm.h
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -98,7 +98,11 @@ extern unsigned int kobjsize(const void 
 #define VM_NORESERVE	0x00200000	/* should the VM suppress accounting */
 #define VM_HUGETLB	0x00400000	/* Huge TLB Page VM */
 #define VM_NONLINEAR	0x00800000	/* Is non-linear (remap_file_pages) */
+#ifndef CONFIG_TRANSPARENT_HUGEPAGE
 #define VM_MAPPED_COPY	0x01000000	/* T if mapped copy of data (nommu mmap) */
+#else
+#define VM_HUGEPAGE	0x01000000	/* MADV_HUGEPAGE marked this vma */
+#endif
 #define VM_INSERTPAGE	0x02000000	/* The vma has had "vm_insert_page()" done on it */
 #define VM_ALWAYSDUMP	0x04000000	/* Always include in core dumps */
 
@@ -107,9 +111,6 @@ extern unsigned int kobjsize(const void 
 #define VM_SAO		0x20000000	/* Strong Access Ordering (powerpc) */
 #define VM_PFN_AT_MMAP	0x40000000	/* PFNMAP vma that is fully mapped at mmap time */
 #define VM_MERGEABLE	0x80000000	/* KSM may merge identical pages */
-#if BITS_PER_LONG > 32
-#define VM_HUGEPAGE	0x100000000UL	/* MADV_HUGEPAGE marked this vma */
-#endif
 
 #ifndef VM_STACK_DEFAULT_FLAGS		/* arch can override this */
 #define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
diff --git a/mm/Kconfig b/mm/Kconfig
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -290,7 +290,7 @@ config NOMMU_INITIAL_TRIM_EXCESS
 
 config TRANSPARENT_HUGEPAGE
 	bool "Transparent Hugepage support" if EMBEDDED
-	depends on X86_64 && MMU
+	depends on X86 && MMU
 	default y
 	help
 	  Transparent Hugepages allows the kernel to use huge pages and

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[PATCH 43 of 67] mincore transparent hugepage support

[Andrea Arcangeli]

From: Johannes Weiner <hannes@cmpxchg.org>

Handle transparent huge page pmd entries natively instead of splitting
them into subpages.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
---

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -19,6 +19,9 @@ extern struct page *follow_trans_huge_pm
 extern int zap_huge_pmd(struct mmu_gather *tlb,
 			struct vm_area_struct *vma,
 			pmd_t *pmd);
+extern int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
+			unsigned long addr, unsigned long end,
+			unsigned char *vec);
 
 enum transparent_hugepage_flag {
 	TRANSPARENT_HUGEPAGE_FLAG,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -936,6 +936,31 @@ int zap_huge_pmd(struct mmu_gather *tlb,
 	return ret;
 }
 
+int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
+		unsigned long addr, unsigned long end,
+		unsigned char *vec)
+{
+	int ret = 0;
+
+	spin_lock(&vma->vm_mm->page_table_lock);
+	if (likely(pmd_trans_huge(*pmd))) {
+		ret = !pmd_trans_splitting(*pmd);
+		spin_unlock(&vma->vm_mm->page_table_lock);
+		if (unlikely(!ret))
+			wait_split_huge_page(vma->anon_vma, pmd);
+		else {
+			/*
+			 * All logical pages in the range are present
+			 * if backed by a huge page.
+			 */
+			memset(vec, 1, (end - addr) >> PAGE_SHIFT);
+		}
+	} else
+		spin_unlock(&vma->vm_mm->page_table_lock);
+
+	return ret;
+}
+
 pmd_t *page_check_address_pmd(struct page *page,
 			      struct mm_struct *mm,
 			      unsigned long address,
diff --git a/mm/mincore.c b/mm/mincore.c
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -154,7 +154,13 @@ static void mincore_pmd_range(struct vm_
 	pmd = pmd_offset(pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
-		split_huge_page_pmd(vma->vm_mm, pmd);
+		if (pmd_trans_huge(*pmd)) {
+			if (mincore_huge_pmd(vma, pmd, addr, next, vec)) {
+				vec += (next - addr) >> PAGE_SHIFT;
+				continue;
+			}
+			/* fall through */
+		}
 		if (pmd_none_or_clear_bad(pmd))
 			mincore_unmapped_range(vma, addr, next, vec);
 		else

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[PATCH 44 of 67] add pmd_modify

[Andrea Arcangeli]

From: Johannes Weiner <hannes@cmpxchg.org>

Add pmd_modify() for use with mprotect() on huge pmds.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
---

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -323,6 +323,16 @@ static inline pte_t pte_modify(pte_t pte
 	return __pte(val);
 }
 
+static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
+{
+	pmdval_t val = pmd_val(pmd);
+
+	val &= _HPAGE_CHG_MASK;
+	val |= massage_pgprot(newprot) & ~_HPAGE_CHG_MASK;
+
+	return __pmd(val);
+}
+
 /* mprotect needs to preserve PAT bits when updating vm_page_prot */
 #define pgprot_modify pgprot_modify
 static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -72,6 +72,7 @@
 /* Set of bits not changed in pte_modify */
 #define _PAGE_CHG_MASK	(PTE_PFN_MASK | _PAGE_PCD | _PAGE_PWT |		\
 			 _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY)
+#define _HPAGE_CHG_MASK (_PAGE_CHG_MASK | _PAGE_PSE)
 
 #define _PAGE_CACHE_MASK	(_PAGE_PCD | _PAGE_PWT)
 #define _PAGE_CACHE_WB		(0)

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[PATCH 45 of 67] mprotect: pass vma down to page table walkers

[Andrea Arcangeli]

From: Johannes Weiner <hannes@cmpxchg.org>

Waiting for huge pmds to finish splitting requires the vma's anon_vma,
so pass along the vma instead of the mm, we can always get the latter
when we need it.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
---

diff --git a/mm/mprotect.c b/mm/mprotect.c
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -35,10 +35,11 @@ static inline pgprot_t pgprot_modify(pgp
 }
 #endif
 
-static void change_pte_range(struct mm_struct *mm, pmd_t *pmd,
+static void change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
 		unsigned long addr, unsigned long end, pgprot_t newprot,
 		int dirty_accountable)
 {
+	struct mm_struct *mm = vma->vm_mm;
 	pte_t *pte, oldpte;
 	spinlock_t *ptl;
 
@@ -78,7 +79,7 @@ static void change_pte_range(struct mm_s
 	pte_unmap_unlock(pte - 1, ptl);
 }
 
-static inline void change_pmd_range(struct mm_struct *mm, pud_t *pud,
+static inline void change_pmd_range(struct vm_area_struct *vma, pud_t *pud,
 		unsigned long addr, unsigned long end, pgprot_t newprot,
 		int dirty_accountable)
 {
@@ -88,14 +89,14 @@ static inline void change_pmd_range(stru
 	pmd = pmd_offset(pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
-		split_huge_page_pmd(mm, pmd);
+		split_huge_page_pmd(vma->vm_mm, pmd);
 		if (pmd_none_or_clear_bad(pmd))
 			continue;
-		change_pte_range(mm, pmd, addr, next, newprot, dirty_accountable);
+		change_pte_range(vma, pmd, addr, next, newprot, dirty_accountable);
 	} while (pmd++, addr = next, addr != end);
 }
 
-static inline void change_pud_range(struct mm_struct *mm, pgd_t *pgd,
+static inline void change_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
 		unsigned long addr, unsigned long end, pgprot_t newprot,
 		int dirty_accountable)
 {
@@ -107,7 +108,7 @@ static inline void change_pud_range(stru
 		next = pud_addr_end(addr, end);
 		if (pud_none_or_clear_bad(pud))
 			continue;
-		change_pmd_range(mm, pud, addr, next, newprot, dirty_accountable);
+		change_pmd_range(vma, pud, addr, next, newprot, dirty_accountable);
 	} while (pud++, addr = next, addr != end);
 }
 
@@ -127,7 +128,7 @@ static void change_protection(struct vm_
 		next = pgd_addr_end(addr, end);
 		if (pgd_none_or_clear_bad(pgd))
 			continue;
-		change_pud_range(mm, pgd, addr, next, newprot, dirty_accountable);
+		change_pud_range(vma, pgd, addr, next, newprot, dirty_accountable);
 	} while (pgd++, addr = next, addr != end);
 	flush_tlb_range(vma, start, end);
 }

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[PATCH 46 of 67] mprotect: transparent huge page support

[Andrea Arcangeli]

From: Johannes Weiner <hannes@cmpxchg.org>

Natively handle huge pmds when changing page tables on behalf of
mprotect().

I left out update_mmu_cache() because we do not need it on x86 anyway
but more importantly the interface works on ptes, not pmds.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
---

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -22,6 +22,8 @@ extern int zap_huge_pmd(struct mmu_gathe
 extern int mincore_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 			unsigned long addr, unsigned long end,
 			unsigned char *vec);
+extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
+			unsigned long addr, pgprot_t newprot);
 
 enum transparent_hugepage_flag {
 	TRANSPARENT_HUGEPAGE_FLAG,
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -961,6 +961,33 @@ int mincore_huge_pmd(struct vm_area_stru
 	return ret;
 }
 
+int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
+		unsigned long addr, pgprot_t newprot)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	int ret = 0;
+
+	spin_lock(&mm->page_table_lock);
+	if (likely(pmd_trans_huge(*pmd))) {
+		if (unlikely(pmd_trans_splitting(*pmd))) {
+			spin_unlock(&mm->page_table_lock);
+			wait_split_huge_page(vma->anon_vma, pmd);
+		} else {
+			pmd_t entry;
+
+			entry = pmdp_get_and_clear(mm, addr, pmd);
+			entry = pmd_modify(entry, newprot);
+			set_pmd_at(mm, addr, pmd, entry);
+			spin_unlock(&vma->vm_mm->page_table_lock);
+			flush_tlb_range(vma, addr, addr + HPAGE_PMD_SIZE);
+			ret = 1;
+		}
+	} else
+		spin_unlock(&vma->vm_mm->page_table_lock);
+
+	return ret;
+}
+
 pmd_t *page_check_address_pmd(struct page *page,
 			      struct mm_struct *mm,
 			      unsigned long address,
diff --git a/mm/mprotect.c b/mm/mprotect.c
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -89,7 +89,13 @@ static inline void change_pmd_range(stru
 	pmd = pmd_offset(pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
-		split_huge_page_pmd(vma->vm_mm, pmd);
+		if (pmd_trans_huge(*pmd)) {
+			if (next - addr != HPAGE_PMD_SIZE)
+				split_huge_page_pmd(vma->vm_mm, pmd);
+			else if (change_huge_pmd(vma, pmd, addr, newprot))
+				continue;
+			/* fall through */
+		}
 		if (pmd_none_or_clear_bad(pmd))
 			continue;
 		change_pte_range(vma, pmd, addr, next, newprot, dirty_accountable);

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[PATCH 47 of 67] set recommended min free kbytes

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

If transparent hugepage is enabled initialize min_free_kbytes to an optimal
value by default. This moves the hugeadm algorithm in kernel.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -86,6 +86,51 @@ struct khugepaged_scan {
 	.mm_head = LIST_HEAD_INIT(khugepaged_scan.mm_head),
 };
 
+
+static int set_recommended_min_free_kbytes(void)
+{
+	struct zone *zone;
+	int nr_zones = 0;
+	unsigned long recommended_min;
+	extern int min_free_kbytes;
+
+	if (!test_bit(TRANSPARENT_HUGEPAGE_FLAG,
+		      &transparent_hugepage_flags) &&
+	    !test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+		      &transparent_hugepage_flags) &&
+	    !test_bit(TRANSPARENT_HUGEPAGE_KHUGEPAGED_FLAG,
+		      &transparent_hugepage_flags) &&
+	    !test_bit(TRANSPARENT_HUGEPAGE_KHUGEPAGED_REQ_MADV_FLAG,
+		      &transparent_hugepage_flags))
+		return 0;
+
+	for_each_populated_zone(zone)
+		nr_zones++;
+
+	/* Make sure at least 2 hugepages are free for MIGRATE_RESERVE */
+	recommended_min = HPAGE_PMD_NR * nr_zones * 2;
+
+	/*
+	 * Make sure that on average at least two pageblocks are almost free
+	 * of another type, one for a migratetype to fall back to and a
+	 * second to avoid subsequent fallbacks of other types There are 3
+	 * MIGRATE_TYPES we care about.
+	 */
+	recommended_min += HPAGE_PMD_NR * nr_zones * 3 * 3;
+
+	/* don't ever allow to reserve more than 5% of the lowmem */
+	recommended_min = min(recommended_min,
+			      (unsigned long) nr_free_buffer_pages() / 20);
+	recommended_min <<= (PAGE_SHIFT-10);
+
+	if (recommended_min > min_free_kbytes) {
+		min_free_kbytes = recommended_min;
+		setup_per_zone_wmarks();
+	}
+	return 0;
+}
+late_initcall(set_recommended_min_free_kbytes);
+
 static int start_khugepaged(void)
 {
 	int err = 0;
@@ -113,6 +158,8 @@ static int start_khugepaged(void)
 		mutex_unlock(&khugepaged_mutex);
 		if (wakeup)
 			wake_up_interruptible(&khugepaged_wait);
+
+		set_recommended_min_free_kbytes();
 	} else
 		/* wakeup to exit */
 		wake_up_interruptible(&khugepaged_wait);
@@ -178,9 +225,20 @@ static ssize_t enabled_store(struct kobj
 			     struct kobj_attribute *attr,
 			     const char *buf, size_t count)
 {
-	return double_flag_store(kobj, attr, buf, count,
-				 TRANSPARENT_HUGEPAGE_FLAG,
-				 TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
+	ssize_t ret;
+
+	ret = double_flag_store(kobj, attr, buf, count,
+				TRANSPARENT_HUGEPAGE_FLAG,
+				TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG);
+
+	if (ret > 0 &&
+	    (test_bit(TRANSPARENT_HUGEPAGE_FLAG,
+		      &transparent_hugepage_flags) ||
+	     test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
+		      &transparent_hugepage_flags)))
+		set_recommended_min_free_kbytes();
+
+	return ret;
 }
 static struct kobj_attribute enabled_attr =
 	__ATTR(enabled, 0644, enabled_show, enabled_store);
@@ -495,6 +553,8 @@ static int __init hugepage_init(void)
 
 	start_khugepaged();
 
+	set_recommended_min_free_kbytes();
+
 out:
 	return err;
 }

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[PATCH 48 of 67] remove lumpy_reclaim

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

Even with memory compaction enabled, without this patch, after:

	echo always >/sys/kernel/mm/transparent_hugepage/defrag

the system becomes unusable and swaps despite gigabytes of clean cache
available in the inactive list. Any frequent high order allocation (despite
being done with noretry/nomemalloc/nowarn) grinds the system to unusable state.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/mm/vmscan.c b/mm/vmscan.c
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1130,7 +1130,6 @@ static unsigned long shrink_inactive_lis
 	unsigned long nr_scanned = 0;
 	unsigned long nr_reclaimed = 0;
 	struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
-	int lumpy_reclaim = 0;
 
 	while (unlikely(too_many_isolated(zone, file, sc))) {
 		congestion_wait(BLK_RW_ASYNC, HZ/10);
@@ -1140,18 +1139,6 @@ static unsigned long shrink_inactive_lis
 			return SWAP_CLUSTER_MAX;
 	}
 
-	/*
-	 * If we need a large contiguous chunk of memory, or have
-	 * trouble getting a small set of contiguous pages, we
-	 * will reclaim both active and inactive pages.
-	 *
-	 * We use the same threshold as pageout congestion_wait below.
-	 */
-	if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
-		lumpy_reclaim = 1;
-	else if (sc->order && priority < DEF_PRIORITY - 2)
-		lumpy_reclaim = 1;
-
 	pagevec_init(&pvec, 1);
 
 	lru_add_drain();
@@ -1163,12 +1150,11 @@ static unsigned long shrink_inactive_lis
 		unsigned long nr_freed;
 		unsigned long nr_active;
 		unsigned int count[NR_LRU_LISTS] = { 0, };
-		int mode = lumpy_reclaim ? ISOLATE_BOTH : ISOLATE_INACTIVE;
 		unsigned long nr_anon;
 		unsigned long nr_file;
 
 		nr_taken = sc->isolate_pages(SWAP_CLUSTER_MAX,
-			     &page_list, &nr_scan, sc->order, mode,
+			     &page_list, &nr_scan, sc->order, ISOLATE_INACTIVE,
 				zone, sc->mem_cgroup, 0, file);
 
 		if (scanning_global_lru(sc)) {
@@ -1209,27 +1195,6 @@ static unsigned long shrink_inactive_lis
 		nr_scanned += nr_scan;
 		nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC);
 
-		/*
-		 * If we are direct reclaiming for contiguous pages and we do
-		 * not reclaim everything in the list, try again and wait
-		 * for IO to complete. This will stall high-order allocations
-		 * but that should be acceptable to the caller
-		 */
-		if (nr_freed < nr_taken && !current_is_kswapd() &&
-		    lumpy_reclaim) {
-			congestion_wait(BLK_RW_ASYNC, HZ/10);
-
-			/*
-			 * The attempt at page out may have made some
-			 * of the pages active, mark them inactive again.
-			 */
-			nr_active = clear_active_flags(&page_list, count);
-			count_vm_events(PGDEACTIVATE, nr_active);
-
-			nr_freed += shrink_page_list(&page_list, sc,
-							PAGEOUT_IO_SYNC);
-		}
-
 		nr_reclaimed += nr_freed;
 
 		local_irq_disable();

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[PATCH 49 of 67] Take a reference to the anon_vma before migrating

[Andrea Arcangeli]

From: Mel Gorman <mel@csn.ul.ie>

rmap_walk_anon() does not use page_lock_anon_vma() for looking up and
locking an anon_vma and it does not appear to have sufficient locking to
ensure the anon_vma does not disappear from under it.

This patch copies an approach used by KSM to take a reference on the
anon_vma while pages are being migrated. This should prevent rmap_walk()
running into nasty surprises later because anon_vma has been freed.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
---

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -29,6 +29,9 @@ struct anon_vma {
 #ifdef CONFIG_KSM
 	atomic_t ksm_refcount;
 #endif
+#ifdef CONFIG_MIGRATION
+	atomic_t migrate_refcount;
+#endif
 	/*
 	 * NOTE: the LSB of the head.next is set by
 	 * mm_take_all_locks() _after_ taking the above lock. So the
@@ -81,6 +84,26 @@ static inline int ksm_refcount(struct an
 	return 0;
 }
 #endif /* CONFIG_KSM */
+#ifdef CONFIG_MIGRATION
+static inline void migrate_refcount_init(struct anon_vma *anon_vma)
+{
+	atomic_set(&anon_vma->migrate_refcount, 0);
+}
+
+static inline int migrate_refcount(struct anon_vma *anon_vma)
+{
+	return atomic_read(&anon_vma->migrate_refcount);
+}
+#else
+static inline void migrate_refcount_init(struct anon_vma *anon_vma)
+{
+}
+
+static inline int migrate_refcount(struct anon_vma *anon_vma)
+{
+	return 0;
+}
+#endif /* CONFIG_MIGRATE */
 
 static inline struct anon_vma *page_anon_vma(struct page *page)
 {
diff --git a/mm/migrate.c b/mm/migrate.c
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -549,6 +549,7 @@ static int unmap_and_move(new_page_t get
 	int rcu_locked = 0;
 	int charge = 0;
 	struct mem_cgroup *mem = NULL;
+	struct anon_vma *anon_vma = NULL;
 
 	if (!newpage)
 		return -ENOMEM;
@@ -608,6 +609,8 @@ static int unmap_and_move(new_page_t get
 	if (PageAnon(page)) {
 		rcu_read_lock();
 		rcu_locked = 1;
+		anon_vma = page_anon_vma(page);
+		atomic_inc(&anon_vma->migrate_refcount);
 	}
 
 	/*
@@ -647,6 +650,15 @@ skip_unmap:
 	if (rc)
 		remove_migration_ptes(page, page);
 rcu_unlock:
+
+	/* Drop an anon_vma reference if we took one */
+	if (anon_vma && atomic_dec_and_lock(&anon_vma->migrate_refcount, &anon_vma->lock)) {
+		int empty = list_empty(&anon_vma->head);
+		spin_unlock(&anon_vma->lock);
+		if (empty)
+			anon_vma_free(anon_vma);
+	}
+
 	if (rcu_locked)
 		rcu_read_unlock();
 uncharge:
diff --git a/mm/rmap.c b/mm/rmap.c
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -250,7 +250,8 @@ static void anon_vma_unlink(struct anon_
 	list_del(&anon_vma_chain->same_anon_vma);
 
 	/* We must garbage collect the anon_vma if it's empty */
-	empty = list_empty(&anon_vma->head) && !ksm_refcount(anon_vma);
+	empty = list_empty(&anon_vma->head) && !ksm_refcount(anon_vma) &&
+					!migrate_refcount(anon_vma);
 	spin_unlock(&anon_vma->lock);
 
 	if (empty)
@@ -275,6 +276,7 @@ static void anon_vma_ctor(void *data)
 
 	spin_lock_init(&anon_vma->lock);
 	ksm_refcount_init(anon_vma);
+	migrate_refcount_init(anon_vma);
 	INIT_LIST_HEAD(&anon_vma->head);
 }
 
@@ -1365,10 +1367,8 @@ static int rmap_walk_anon(struct page *p
 	/*
 	 * Note: remove_migration_ptes() cannot use page_lock_anon_vma()
 	 * because that depends on page_mapped(); but not all its usages
-	 * are holding mmap_sem, which also gave the necessary guarantee
-	 * (that this anon_vma's slab has not already been destroyed).
-	 * This needs to be reviewed later: avoiding page_lock_anon_vma()
-	 * is risky, and currently limits the usefulness of rmap_walk().
+	 * are holding mmap_sem. Users without mmap_sem are required to
+	 * take a reference count to prevent the anon_vma disappearing
 	 */
 	anon_vma = page_anon_vma(page);
 	if (!anon_vma)

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[PATCH 50 of 67] Do not try to migrate unmapped anonymous pages

[Andrea Arcangeli]

From: Mel Gorman <mel@csn.ul.ie>

rmap_walk_anon() was triggering errors in memory compaction that look like
use-after-free errors. The problem is that between the page being isolated
from the LRU and rcu_read_lock() being taken, the mapcount of the page
dropped to 0 and the anon_vma gets freed. This can happen during memory
compaction if pages being migrated belong to a process that exits before
migration completes. Hence, the use-after-free race looks like

 1. Page isolated for migration
 2. Process exits
 3. page_mapcount(page) drops to zero so anon_vma was no longer reliable
 4. unmap_and_move() takes the rcu_lock but the anon_vma is already garbage
 4. call try_to_unmap, looks up tha anon_vma and "locks" it but the lock
    is garbage.

This patch checks the mapcount after the rcu lock is taken. If the
mapcount is zero, the anon_vma is assumed to be freed and no further
action is taken.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---

diff --git a/mm/migrate.c b/mm/migrate.c
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -609,6 +609,17 @@ static int unmap_and_move(new_page_t get
 	if (PageAnon(page)) {
 		rcu_read_lock();
 		rcu_locked = 1;
+
+		/*
+		 * If the page has no mappings any more, just bail. An
+		 * unmapped anon page is likely to be freed soon but worse,
+		 * it's possible its anon_vma disappeared between when
+		 * the page was isolated and when we reached here while
+		 * the RCU lock was not held
+		 */
+		if (!page_mapped(page))
+			goto rcu_unlock;
+
 		anon_vma = page_anon_vma(page);
 		atomic_inc(&anon_vma->migrate_refcount);
 	}

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[PATCH 51 of 67] Share the anon_vma ref counts between KSM and page migration

[Andrea Arcangeli]

From: Mel Gorman <mel@csn.ul.ie>

For clarity of review, KSM and page migration have separate refcounts on
the anon_vma. While clear, this is a waste of memory. This patch gets
KSM and page migration to share their toys in a spirit of harmony.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -26,11 +26,17 @@
  */
 struct anon_vma {
 	spinlock_t lock;	/* Serialize access to vma list */
-#ifdef CONFIG_KSM
-	atomic_t ksm_refcount;
-#endif
-#ifdef CONFIG_MIGRATION
-	atomic_t migrate_refcount;
+#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
+
+	/*
+	 * The external_refcount is taken by either KSM or page migration
+	 * to take a reference to an anon_vma when there is no
+	 * guarantee that the vma of page tables will exist for
+	 * the duration of the operation. A caller that takes
+	 * the reference is responsible for clearing up the
+	 * anon_vma if they are the last user on release
+	 */
+	atomic_t external_refcount;
 #endif
 	/*
 	 * NOTE: the LSB of the head.next is set by
@@ -64,46 +70,26 @@ struct anon_vma_chain {
 };
 
 #ifdef CONFIG_MMU
-#ifdef CONFIG_KSM
-static inline void ksm_refcount_init(struct anon_vma *anon_vma)
+#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
+static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
 {
-	atomic_set(&anon_vma->ksm_refcount, 0);
+	atomic_set(&anon_vma->external_refcount, 0);
 }
 
-static inline int ksm_refcount(struct anon_vma *anon_vma)
+static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
 {
-	return atomic_read(&anon_vma->ksm_refcount);
+	return atomic_read(&anon_vma->external_refcount);
 }
 #else
-static inline void ksm_refcount_init(struct anon_vma *anon_vma)
+static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
 {
 }
 
-static inline int ksm_refcount(struct anon_vma *anon_vma)
+static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
 {
 	return 0;
 }
 #endif /* CONFIG_KSM */
-#ifdef CONFIG_MIGRATION
-static inline void migrate_refcount_init(struct anon_vma *anon_vma)
-{
-	atomic_set(&anon_vma->migrate_refcount, 0);
-}
-
-static inline int migrate_refcount(struct anon_vma *anon_vma)
-{
-	return atomic_read(&anon_vma->migrate_refcount);
-}
-#else
-static inline void migrate_refcount_init(struct anon_vma *anon_vma)
-{
-}
-
-static inline int migrate_refcount(struct anon_vma *anon_vma)
-{
-	return 0;
-}
-#endif /* CONFIG_MIGRATE */
 
 static inline struct anon_vma *page_anon_vma(struct page *page)
 {
diff --git a/mm/ksm.c b/mm/ksm.c
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -318,14 +318,14 @@ static void hold_anon_vma(struct rmap_it
 			  struct anon_vma *anon_vma)
 {
 	rmap_item->anon_vma = anon_vma;
-	atomic_inc(&anon_vma->ksm_refcount);
+	atomic_inc(&anon_vma->external_refcount);
 }
 
 static void drop_anon_vma(struct rmap_item *rmap_item)
 {
 	struct anon_vma *anon_vma = rmap_item->anon_vma;
 
-	if (atomic_dec_and_lock(&anon_vma->ksm_refcount, &anon_vma->lock)) {
+	if (atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->lock)) {
 		int empty = list_empty(&anon_vma->head);
 		spin_unlock(&anon_vma->lock);
 		if (empty)
diff --git a/mm/migrate.c b/mm/migrate.c
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -621,7 +621,7 @@ static int unmap_and_move(new_page_t get
 			goto rcu_unlock;
 
 		anon_vma = page_anon_vma(page);
-		atomic_inc(&anon_vma->migrate_refcount);
+		atomic_inc(&anon_vma->external_refcount);
 	}
 
 	/*
@@ -663,7 +663,7 @@ skip_unmap:
 rcu_unlock:
 
 	/* Drop an anon_vma reference if we took one */
-	if (anon_vma && atomic_dec_and_lock(&anon_vma->migrate_refcount, &anon_vma->lock)) {
+	if (anon_vma && atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->lock)) {
 		int empty = list_empty(&anon_vma->head);
 		spin_unlock(&anon_vma->lock);
 		if (empty)
diff --git a/mm/rmap.c b/mm/rmap.c
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -250,8 +250,7 @@ static void anon_vma_unlink(struct anon_
 	list_del(&anon_vma_chain->same_anon_vma);
 
 	/* We must garbage collect the anon_vma if it's empty */
-	empty = list_empty(&anon_vma->head) && !ksm_refcount(anon_vma) &&
-					!migrate_refcount(anon_vma);
+	empty = list_empty(&anon_vma->head) && !anonvma_external_refcount(anon_vma);
 	spin_unlock(&anon_vma->lock);
 
 	if (empty)
@@ -275,8 +274,7 @@ static void anon_vma_ctor(void *data)
 	struct anon_vma *anon_vma = data;
 
 	spin_lock_init(&anon_vma->lock);
-	ksm_refcount_init(anon_vma);
-	migrate_refcount_init(anon_vma);
+	anonvma_external_refcount_init(anon_vma);
 	INIT_LIST_HEAD(&anon_vma->head);
 }
 

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[PATCH 52 of 67] Allow CONFIG_MIGRATION to be set without CONFIG_NUMA or memory hot-remove

[Andrea Arcangeli]

From: Mel Gorman <mel@csn.ul.ie>

CONFIG_MIGRATION currently depends on CONFIG_NUMA or on the architecture
being able to hot-remove memory. The main users of page migration such as
sys_move_pages(), sys_migrate_pages() and cpuset process migration are
only beneficial on NUMA so it makes sense.

As memory compaction will operate within a zone and is useful on both NUMA
and non-NUMA systems, this patch allows CONFIG_MIGRATION to be set if the
user selects CONFIG_COMPACTION as an option.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---

diff --git a/mm/Kconfig b/mm/Kconfig
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -172,6 +172,16 @@ config SPLIT_PTLOCK_CPUS
 	default "4"
 
 #
+# support for memory compaction
+config COMPACTION
+	bool "Allow for memory compaction"
+	def_bool y
+	select MIGRATION
+	depends on EXPERIMENTAL && HUGETLB_PAGE && MMU
+	help
+	  Allows the compaction of memory for the allocation of huge pages.
+
+#
 # support for page migration
 #
 config MIGRATION
@@ -180,9 +190,11 @@ config MIGRATION
 	depends on NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE
 	help
 	  Allows the migration of the physical location of pages of processes
-	  while the virtual addresses are not changed. This is useful for
-	  example on NUMA systems to put pages nearer to the processors accessing
-	  the page.
+	  while the virtual addresses are not changed. This is useful in
+	  two situations. The first is on NUMA systems to put pages nearer
+	  to the processors accessing. The second is when allocating huge
+	  pages as migration can relocate pages to satisfy a huge page
+	  allocation instead of reclaiming.
 
 config PHYS_ADDR_T_64BIT
 	def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT

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[PATCH 53 of 67] Export unusable free space index via /proc/unusable_index

[Andrea Arcangeli]

From: Mel Gorman <mel@csn.ul.ie>

Unusable free space index is a measure of external fragmentation that
takes the allocation size into account. For the most part, the huge page
size will be the size of interest but not necessarily so it is exported
on a per-order and per-zone basis via /proc/unusable_index.

The index is a value between 0 and 1. It can be expressed as a
percentage by multiplying by 100 as documented in
Documentation/filesystems/proc.txt.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
---

diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -451,6 +451,7 @@ Table 1-5: Kernel info in /proc
  sys         See chapter 2                                     
  sysvipc     Info of SysVIPC Resources (msg, sem, shm)		(2.4)
  tty	     Info of tty drivers
+ unusable_index Additional page allocator information (see text)(2.5)
  uptime      System uptime                                     
  version     Kernel version                                    
  video	     bttv info of video resources			(2.4)
@@ -604,7 +605,7 @@ ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in Z
 available in ZONE_NORMAL, etc... 
 
 More information relevant to external fragmentation can be found in
-pagetypeinfo.
+pagetypeinfo and unusable_index
 
 > cat /proc/pagetypeinfo
 Page block order: 9
@@ -645,6 +646,16 @@ unless memory has been mlock()'d. Some o
 also be allocatable although a lot of filesystem metadata may have to be
 reclaimed to achieve this.
 
+> cat /proc/unusable_index
+Node 0, zone      DMA 0.000 0.000 0.000 0.001 0.005 0.013 0.021 0.037 0.037 0.101 0.230
+Node 0, zone   Normal 0.000 0.000 0.000 0.001 0.002 0.002 0.005 0.015 0.028 0.028 0.054
+
+The unusable free space index measures how much of the available free
+memory cannot be used to satisfy an allocation of a given size and is a
+value between 0 and 1. The higher the value, the more of free memory is
+unusable and by implication, the worse the external fragmentation is. This
+can be expressed as a percentage by multiplying by 100.
+
 ..............................................................................
 
 meminfo:
diff --git a/mm/vmstat.c b/mm/vmstat.c
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -454,6 +454,106 @@ static int frag_show(struct seq_file *m,
 	return 0;
 }
 
+
+struct contig_page_info {
+	unsigned long free_pages;
+	unsigned long free_blocks_total;
+	unsigned long free_blocks_suitable;
+};
+
+/*
+ * Calculate the number of free pages in a zone, how many contiguous
+ * pages are free and how many are large enough to satisfy an allocation of
+ * the target size. Note that this function makes no attempt to estimate
+ * how many suitable free blocks there *might* be if MOVABLE pages were
+ * migrated. Calculating that is possible, but expensive and can be
+ * figured out from userspace
+ */
+static void fill_contig_page_info(struct zone *zone,
+				unsigned int suitable_order,
+				struct contig_page_info *info)
+{
+	unsigned int order;
+
+	info->free_pages = 0;
+	info->free_blocks_total = 0;
+	info->free_blocks_suitable = 0;
+
+	for (order = 0; order < MAX_ORDER; order++) {
+		unsigned long blocks;
+
+		/* Count number of free blocks */
+		blocks = zone->free_area[order].nr_free;
+		info->free_blocks_total += blocks;
+
+		/* Count free base pages */
+		info->free_pages += blocks << order;
+
+		/* Count the suitable free blocks */
+		if (order >= suitable_order)
+			info->free_blocks_suitable += blocks <<
+						(order - suitable_order);
+	}
+}
+
+/*
+ * Return an index indicating how much of the available free memory is
+ * unusable for an allocation of the requested size.
+ */
+static int unusable_free_index(unsigned int order,
+				struct contig_page_info *info)
+{
+	/* No free memory is interpreted as all free memory is unusable */
+	if (info->free_pages == 0)
+		return 1000;
+
+	/*
+	 * Index should be a value between 0 and 1. Return a value to 3
+	 * decimal places.
+	 *
+	 * 0 => no fragmentation
+	 * 1 => high fragmentation
+	 */
+	return div_u64((info->free_pages - (info->free_blocks_suitable << order)) * 1000ULL, info->free_pages);
+
+}
+
+static void unusable_show_print(struct seq_file *m,
+					pg_data_t *pgdat, struct zone *zone)
+{
+	unsigned int order;
+	int index;
+	struct contig_page_info info;
+
+	seq_printf(m, "Node %d, zone %8s ",
+				pgdat->node_id,
+				zone->name);
+	for (order = 0; order < MAX_ORDER; ++order) {
+		fill_contig_page_info(zone, order, &info);
+		index = unusable_free_index(order, &info);
+		seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
+	}
+
+	seq_putc(m, '\n');
+}
+
+/*
+ * Display unusable free space index
+ * XXX: Could be a lot more efficient, but it's not a critical path
+ */
+static int unusable_show(struct seq_file *m, void *arg)
+{
+	pg_data_t *pgdat = (pg_data_t *)arg;
+
+	/* check memoryless node */
+	if (!node_state(pgdat->node_id, N_HIGH_MEMORY))
+		return 0;
+
+	walk_zones_in_node(m, pgdat, unusable_show_print);
+
+	return 0;
+}
+
 static void pagetypeinfo_showfree_print(struct seq_file *m,
 					pg_data_t *pgdat, struct zone *zone)
 {
@@ -604,6 +704,25 @@ static const struct file_operations page
 	.release	= seq_release,
 };
 
+static const struct seq_operations unusable_op = {
+	.start	= frag_start,
+	.next	= frag_next,
+	.stop	= frag_stop,
+	.show	= unusable_show,
+};
+
+static int unusable_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &unusable_op);
+}
+
+static const struct file_operations unusable_file_ops = {
+	.open		= unusable_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
 #ifdef CONFIG_ZONE_DMA
 #define TEXT_FOR_DMA(xx) xx "_dma",
 #else
@@ -951,6 +1070,7 @@ static int __init setup_vmstat(void)
 #ifdef CONFIG_PROC_FS
 	proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);
 	proc_create("pagetypeinfo", S_IRUGO, NULL, &pagetypeinfo_file_ops);
+	proc_create("unusable_index", S_IRUGO, NULL, &unusable_file_ops);
 	proc_create("vmstat", S_IRUGO, NULL, &proc_vmstat_file_operations);
 	proc_create("zoneinfo", S_IRUGO, NULL, &proc_zoneinfo_file_operations);
 #endif

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[PATCH 54 of 67] Export fragmentation index via /proc/extfrag_index

[Andrea Arcangeli]

From: Mel Gorman <mel@csn.ul.ie>

Fragmentation index is a value that makes sense when an allocation of a
given size would fail. The index indicates whether an allocation failure is
due to a lack of memory (values towards 0) or due to external fragmentation
(value towards 1).  For the most part, the huge page size will be the size
of interest but not necessarily so it is exported on a per-order and per-zone
basis via /proc/extfrag_index

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
---

diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -420,6 +420,7 @@ Table 1-5: Kernel info in /proc
  filesystems Supported filesystems                             
  driver	     Various drivers grouped here, currently rtc (2.4)
  execdomains Execdomains, related to security			(2.4)
+ extfrag_index Additional page allocator information (see text) (2.5)
  fb	     Frame Buffer devices				(2.4)
  fs	     File system parameters, currently nfs/exports	(2.4)
  ide         Directory containing info about the IDE subsystem 
@@ -605,7 +606,7 @@ ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in Z
 available in ZONE_NORMAL, etc... 
 
 More information relevant to external fragmentation can be found in
-pagetypeinfo and unusable_index
+pagetypeinfo, unusable_index and extfrag_index.
 
 > cat /proc/pagetypeinfo
 Page block order: 9
@@ -656,6 +657,17 @@ value between 0 and 1. The higher the va
 unusable and by implication, the worse the external fragmentation is. This
 can be expressed as a percentage by multiplying by 100.
 
+> cat /proc/extfrag_index
+Node 0, zone      DMA -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.00
+Node 0, zone   Normal -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 -1.000 0.954
+
+The external fragmentation index, is only meaningful if an allocation
+would fail and indicates what the failure is due to. A value of -1 such as
+in many of the examples above states that the allocation would succeed.
+If it would fail, the value is between 0 and 1. A value tending towards
+0 implies the allocation failed due to a lack of memory. A value tending
+towards 1 implies it failed due to external fragmentation.
+
 ..............................................................................
 
 meminfo:
diff --git a/mm/vmstat.c b/mm/vmstat.c
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -16,6 +16,7 @@
 #include <linux/cpu.h>
 #include <linux/vmstat.h>
 #include <linux/sched.h>
+#include <linux/math64.h>
 
 #ifdef CONFIG_VM_EVENT_COUNTERS
 DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
@@ -554,6 +555,67 @@ static int unusable_show(struct seq_file
 	return 0;
 }
 
+/*
+ * A fragmentation index only makes sense if an allocation of a requested
+ * size would fail. If that is true, the fragmentation index indicates
+ * whether external fragmentation or a lack of memory was the problem.
+ * The value can be used to determine if page reclaim or compaction
+ * should be used
+ */
+int fragmentation_index(unsigned int order, struct contig_page_info *info)
+{
+	unsigned long requested = 1UL << order;
+
+	if (!info->free_blocks_total)
+		return 0;
+
+	/* Fragmentation index only makes sense when a request would fail */
+	if (info->free_blocks_suitable)
+		return -1000;
+
+	/*
+	 * Index is between 0 and 1 so return within 3 decimal places
+	 *
+	 * 0 => allocation would fail due to lack of memory
+	 * 1 => allocation would fail due to fragmentation
+	 */
+	return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
+}
+
+
+static void extfrag_show_print(struct seq_file *m,
+					pg_data_t *pgdat, struct zone *zone)
+{
+	unsigned int order;
+	int index;
+
+	/* Alloc on stack as interrupts are disabled for zone walk */
+	struct contig_page_info info;
+
+	seq_printf(m, "Node %d, zone %8s ",
+				pgdat->node_id,
+				zone->name);
+	for (order = 0; order < MAX_ORDER; ++order) {
+		fill_contig_page_info(zone, order, &info);
+		index = fragmentation_index(order, &info);
+		seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
+	}
+
+	seq_putc(m, '\n');
+}
+
+/*
+ * Display fragmentation index for orders that allocations would fail for
+ */
+static int extfrag_show(struct seq_file *m, void *arg)
+{
+	pg_data_t *pgdat = (pg_data_t *)arg;
+
+	walk_zones_in_node(m, pgdat, extfrag_show_print);
+
+	return 0;
+}
+
 static void pagetypeinfo_showfree_print(struct seq_file *m,
 					pg_data_t *pgdat, struct zone *zone)
 {
@@ -723,6 +785,25 @@ static const struct file_operations unus
 	.release	= seq_release,
 };
 
+static const struct seq_operations extfrag_op = {
+	.start	= frag_start,
+	.next	= frag_next,
+	.stop	= frag_stop,
+	.show	= extfrag_show,
+};
+
+static int extfrag_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &extfrag_op);
+}
+
+static const struct file_operations extfrag_file_ops = {
+	.open		= extfrag_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
 #ifdef CONFIG_ZONE_DMA
 #define TEXT_FOR_DMA(xx) xx "_dma",
 #else
@@ -1071,6 +1152,7 @@ static int __init setup_vmstat(void)
 	proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);
 	proc_create("pagetypeinfo", S_IRUGO, NULL, &pagetypeinfo_file_ops);
 	proc_create("unusable_index", S_IRUGO, NULL, &unusable_file_ops);
+	proc_create("extfrag_index", S_IRUGO, NULL, &extfrag_file_ops);
 	proc_create("vmstat", S_IRUGO, NULL, &proc_vmstat_file_operations);
 	proc_create("zoneinfo", S_IRUGO, NULL, &proc_zoneinfo_file_operations);
 #endif

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[PATCH 55 of 67] Move definition for LRU isolation modes to a header

[Andrea Arcangeli]

From: Mel Gorman <mel@csn.ul.ie>

Currently, vmscan.c defines the isolation modes for
__isolate_lru_page(). Memory compaction needs access to these modes for
isolating pages for migration.  This patch exports them.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
---

diff --git a/include/linux/swap.h b/include/linux/swap.h
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -240,6 +240,11 @@ static inline void lru_cache_add_active_
 	__lru_cache_add(page, LRU_ACTIVE_FILE);
 }
 
+/* LRU Isolation modes. */
+#define ISOLATE_INACTIVE 0	/* Isolate inactive pages. */
+#define ISOLATE_ACTIVE 1	/* Isolate active pages. */
+#define ISOLATE_BOTH 2		/* Isolate both active and inactive pages. */
+
 /* linux/mm/vmscan.c */
 extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 					gfp_t gfp_mask, nodemask_t *mask);
diff --git a/mm/vmscan.c b/mm/vmscan.c
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -839,11 +839,6 @@ keep:
 	return nr_reclaimed;
 }
 
-/* LRU Isolation modes. */
-#define ISOLATE_INACTIVE 0	/* Isolate inactive pages. */
-#define ISOLATE_ACTIVE 1	/* Isolate active pages. */
-#define ISOLATE_BOTH 2		/* Isolate both active and inactive pages. */
-
 /*
  * Attempt to remove the specified page from its LRU.  Only take this page
  * if it is of the appropriate PageActive status.  Pages which are being

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[PATCH 56 of 67] Memory compaction core

[Andrea Arcangeli]

From: Mel Gorman <mel@csn.ul.ie>

This patch is the core of a mechanism which compacts memory in a zone by
relocating movable pages towards the end of the zone.

A single compaction run involves a migration scanner and a free scanner.
Both scanners operate on pageblock-sized areas in the zone. The migration
scanner starts at the bottom of the zone and searches for all movable pages
within each area, isolating them onto a private list called migratelist.
The free scanner starts at the top of the zone and searches for suitable
areas and consumes the free pages within making them available for the
migration scanner. The pages isolated for migration are then migrated to
the newly isolated free pages.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
---

diff --git a/include/linux/compaction.h b/include/linux/compaction.h
new file mode 100644
--- /dev/null
+++ b/include/linux/compaction.h
@@ -0,0 +1,9 @@
+#ifndef _LINUX_COMPACTION_H
+#define _LINUX_COMPACTION_H
+
+/* Return values for compact_zone() */
+#define COMPACT_INCOMPLETE	0
+#define COMPACT_PARTIAL		1
+#define COMPACT_COMPLETE	2
+
+#endif /* _LINUX_COMPACTION_H */
diff --git a/include/linux/mm.h b/include/linux/mm.h
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -384,6 +384,7 @@ void put_page(struct page *page);
 void put_pages_list(struct list_head *pages);
 
 void split_page(struct page *page, unsigned int order);
+int split_free_page(struct page *page);
 
 /*
  * Compound pages have a destructor function.  Provide a
diff --git a/include/linux/swap.h b/include/linux/swap.h
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -151,6 +151,7 @@ enum {
 };
 
 #define SWAP_CLUSTER_MAX 32
+#define COMPACT_CLUSTER_MAX SWAP_CLUSTER_MAX
 
 #define SWAP_MAP_MAX	0x3e	/* Max duplication count, in first swap_map */
 #define SWAP_MAP_BAD	0x3f	/* Note pageblock is bad, in first swap_map */
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -43,6 +43,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
 		KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY,
 		KSWAPD_SKIP_CONGESTION_WAIT,
 		PAGEOUTRUN, ALLOCSTALL, PGROTATED,
+		COMPACTBLOCKS, COMPACTPAGES, COMPACTPAGEFAILED,
 #ifdef CONFIG_HUGETLB_PAGE
 		HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
 #endif
diff --git a/mm/Makefile b/mm/Makefile
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -33,6 +33,7 @@ obj-$(CONFIG_FAILSLAB) += failslab.o
 obj-$(CONFIG_MEMORY_HOTPLUG) += memory_hotplug.o
 obj-$(CONFIG_FS_XIP) += filemap_xip.o
 obj-$(CONFIG_MIGRATION) += migrate.o
+obj-$(CONFIG_COMPACTION) += compaction.o
 ifdef CONFIG_SMP
 obj-y += percpu.o
 else
diff --git a/mm/compaction.c b/mm/compaction.c
new file mode 100644
--- /dev/null
+++ b/mm/compaction.c
@@ -0,0 +1,390 @@
+/*
+ * linux/mm/compaction.c
+ *
+ * Memory compaction for the reduction of external fragmentation. Note that
+ * this heavily depends upon page migration to do all the real heavy
+ * lifting
+ *
+ * Copyright IBM Corp. 2007-2010 Mel Gorman <mel@csn.ul.ie>
+ */
+#include <linux/swap.h>
+#include <linux/migrate.h>
+#include <linux/compaction.h>
+#include <linux/mm_inline.h>
+#include <linux/backing-dev.h>
+#include "internal.h"
+
+/*
+ * compact_control is used to track pages being migrated and the free pages
+ * they are being migrated to during memory compaction. The free_pfn starts
+ * at the end of a zone and migrate_pfn begins at the start. Movable pages
+ * are moved to the end of a zone during a compaction run and the run
+ * completes when free_pfn <= migrate_pfn
+ */
+struct compact_control {
+	struct list_head freepages;	/* List of free pages to migrate to */
+	struct list_head migratepages;	/* List of pages being migrated */
+	unsigned long nr_freepages;	/* Number of isolated free pages */
+	unsigned long nr_migratepages;	/* Number of pages to migrate */
+	unsigned long free_pfn;		/* isolate_freepages search base */
+	unsigned long migrate_pfn;	/* isolate_migratepages search base */
+
+	/* Account for isolated anon and file pages */
+	unsigned long nr_anon;
+	unsigned long nr_file;
+
+	struct zone *zone;
+};
+
+static unsigned long release_freepages(struct list_head *freelist)
+{
+	struct page *page, *next;
+	unsigned long count = 0;
+
+	list_for_each_entry_safe(page, next, freelist, lru) {
+		list_del(&page->lru);
+		__free_page(page);
+		count++;
+	}
+
+	return count;
+}
+
+/* Isolate free pages onto a private freelist. Must hold zone->lock */
+static unsigned long isolate_freepages_block(struct zone *zone,
+				unsigned long blockpfn,
+				struct list_head *freelist)
+{
+	unsigned long zone_end_pfn, end_pfn;
+	int total_isolated = 0;
+	struct page *cursor;
+
+	/* Get the last PFN we should scan for free pages at */
+	zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
+	end_pfn = min(blockpfn + pageblock_nr_pages, zone_end_pfn);
+
+	/* Find the first usable PFN in the block to initialse page cursor */
+	for (; blockpfn < end_pfn; blockpfn++) {
+		if (pfn_valid_within(blockpfn))
+			break;
+	}
+	cursor = pfn_to_page(blockpfn);
+
+	/* Isolate free pages. This assumes the block is valid */
+	for (; blockpfn < end_pfn; blockpfn++, cursor++) {
+		int isolated, i;
+		struct page *page = cursor;
+
+		if (!pfn_valid_within(blockpfn))
+			continue;
+
+		if (!PageBuddy(page))
+			continue;
+
+		/* Found a free page, break it into order-0 pages */
+		isolated = split_free_page(page);
+		total_isolated += isolated;
+		for (i = 0; i < isolated; i++) {
+			list_add(&page->lru, freelist);
+			page++;
+		}
+
+		/* If a page was split, advance to the end of it */
+		if (isolated) {
+			blockpfn += isolated - 1;
+			cursor += isolated - 1;
+		}
+	}
+
+	return total_isolated;
+}
+
+/* Returns true if the page is within a block suitable for migration to */
+static bool suitable_migration_target(struct page *page)
+{
+
+	int migratetype = get_pageblock_migratetype(page);
+
+	/* Don't interfere with memory hot-remove or the min_free_kbytes blocks */
+	if (migratetype == MIGRATE_ISOLATE || migratetype == MIGRATE_RESERVE)
+		return false;
+
+	/* If the page is a large free page, then allow migration */
+	if (PageBuddy(page) && page_order(page) >= pageblock_order)
+		return true;
+
+	/* If the block is MIGRATE_MOVABLE, allow migration */
+	if (migratetype == MIGRATE_MOVABLE)
+		return true;
+
+	/* Otherwise skip the block */
+	return false;
+}
+
+/*
+ * Based on information in the current compact_control, find blocks
+ * suitable for isolating free pages from and then isolate them.
+ */
+static void isolate_freepages(struct zone *zone,
+				struct compact_control *cc)
+{
+	struct page *page;
+	unsigned long high_pfn, low_pfn, pfn;
+	unsigned long flags;
+	int nr_freepages = cc->nr_freepages;
+	struct list_head *freelist = &cc->freepages;
+
+	pfn = cc->free_pfn;
+	low_pfn = cc->migrate_pfn + pageblock_nr_pages;
+	high_pfn = low_pfn;
+
+	/*
+	 * Isolate free pages until enough are available to migrate the
+	 * pages on cc->migratepages. We stop searching if the migrate
+	 * and free page scanners meet or enough free pages are isolated.
+	 */
+	spin_lock_irqsave(&zone->lock, flags);
+	for (; pfn > low_pfn && cc->nr_migratepages > nr_freepages;
+					pfn -= pageblock_nr_pages) {
+		unsigned long isolated;
+
+		if (!pfn_valid(pfn))
+			continue;
+
+		/* 
+		 * Check for overlapping nodes/zones. It's possible on some
+		 * configurations to have a setup like
+		 * node0 node1 node0
+		 * i.e. it's possible that all pages within a zones range of
+		 * pages do not belong to a single zone.
+		 */
+		page = pfn_to_page(pfn);
+		if (page_zone(page) != zone)
+			continue;
+
+		/* Check the block is suitable for migration */
+		if (!suitable_migration_target(page))
+			continue;
+
+		/* Found a block suitable for isolating free pages from */
+		isolated = isolate_freepages_block(zone, pfn, freelist);
+		nr_freepages += isolated;
+
+		/*
+		 * Record the highest PFN we isolated pages from. When next
+		 * looking for free pages, the search will restart here as
+		 * page migration may have returned some pages to the allocator
+		 */
+		if (isolated)
+			high_pfn = max(high_pfn, pfn);
+	}
+	spin_unlock_irqrestore(&zone->lock, flags);
+
+	cc->free_pfn = high_pfn;
+	cc->nr_freepages = nr_freepages;
+}
+
+/* Update the number of anon and file isolated pages in the zone */
+static void acct_isolated(struct zone *zone, struct compact_control *cc)
+{
+	struct page *page;
+	unsigned int count[NR_LRU_LISTS] = { 0, };
+
+	list_for_each_entry(page, &cc->migratepages, lru) {
+		int lru = page_lru_base_type(page);
+		count[lru]++;
+	}
+
+	cc->nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
+	cc->nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
+	__mod_zone_page_state(zone, NR_ISOLATED_ANON, cc->nr_anon);
+	__mod_zone_page_state(zone, NR_ISOLATED_FILE, cc->nr_file);
+}
+
+/* Similar to reclaim, but different enough that they don't share logic */
+static bool too_many_isolated(struct zone *zone)
+{
+
+	unsigned long inactive, isolated;
+
+	inactive = zone_page_state(zone, NR_INACTIVE_FILE) +
+					zone_page_state(zone, NR_INACTIVE_ANON);
+	isolated = zone_page_state(zone, NR_ISOLATED_FILE) +
+					zone_page_state(zone, NR_ISOLATED_ANON);
+
+	return isolated > inactive;
+}
+
+/*
+ * Isolate all pages that can be migrated from the block pointed to by
+ * the migrate scanner within compact_control.
+ */
+static unsigned long isolate_migratepages(struct zone *zone,
+					struct compact_control *cc)
+{
+	unsigned long low_pfn, end_pfn;
+	struct list_head *migratelist = &cc->migratepages;
+
+	/* Do not scan outside zone boundaries */
+	low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn);
+
+	/* Only scan within a pageblock boundary */
+	end_pfn = ALIGN(low_pfn + pageblock_nr_pages, pageblock_nr_pages);
+
+	/* Do not cross the free scanner or scan within a memory hole */
+	if (end_pfn > cc->free_pfn || !pfn_valid(low_pfn)) {
+		cc->migrate_pfn = end_pfn;
+		return 0;
+	}
+
+	/*
+	 * Ensure that there are not too many pages isolated from the LRU
+	 * list by either parallel reclaimers or compaction. If there are,
+	 * delay for some time until fewer pages are isolated
+	 */
+	while (unlikely(too_many_isolated(zone))) {
+		congestion_wait(BLK_RW_ASYNC, HZ/10);
+
+		if (fatal_signal_pending(current))
+			return 0;
+	}
+
+	/* Time to isolate some pages for migration */
+	spin_lock_irq(&zone->lru_lock);
+	for (; low_pfn < end_pfn; low_pfn++) {
+		struct page *page;
+		if (!pfn_valid_within(low_pfn))
+			continue;
+
+		/* Get the page and skip if free */
+		page = pfn_to_page(low_pfn);
+		if (PageBuddy(page)) {
+			low_pfn += (1 << page_order(page)) - 1;
+			continue;
+		}
+
+		/* Try isolate the page */
+		if (__isolate_lru_page(page, ISOLATE_BOTH, 0) != 0)
+			continue;
+
+		/* Successfully isolated */
+		del_page_from_lru_list(zone, page, page_lru(page));
+		list_add(&page->lru, migratelist);
+		mem_cgroup_del_lru(page);
+		cc->nr_migratepages++;
+
+		/* Avoid isolating too much */
+		if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
+			break;
+	}
+
+	acct_isolated(zone, cc);
+
+	spin_unlock_irq(&zone->lru_lock);
+	cc->migrate_pfn = low_pfn;
+
+	return cc->nr_migratepages;
+}
+
+/*
+ * This is a migrate-callback that "allocates" freepages by taking pages
+ * from the isolated freelists in the block we are migrating to.
+ */
+static struct page *compaction_alloc(struct page *migratepage,
+					unsigned long data,
+					int **result)
+{
+	struct compact_control *cc = (struct compact_control *)data;
+	struct page *freepage;
+
+	/* Isolate free pages if necessary */
+	if (list_empty(&cc->freepages)) {
+		isolate_freepages(cc->zone, cc);
+
+		if (list_empty(&cc->freepages))
+			return NULL;
+	}
+
+	freepage = list_entry(cc->freepages.next, struct page, lru);
+	list_del(&freepage->lru);
+	cc->nr_freepages--;
+
+	return freepage;
+}
+
+/*
+ * We cannot control nr_migratepages and nr_freepages fully when migration is
+ * running as migrate_pages() has no knowledge of compact_control. When
+ * migration is complete, we count the number of pages on the lists by hand.
+ */
+static void update_nr_listpages(struct compact_control *cc)
+{
+	int nr_migratepages = 0;
+	int nr_freepages = 0;
+	struct page *page;
+
+	list_for_each_entry(page, &cc->migratepages, lru)
+		nr_migratepages++;
+	list_for_each_entry(page, &cc->freepages, lru)
+		nr_freepages++;
+
+	cc->nr_migratepages = nr_migratepages;
+	cc->nr_freepages = nr_freepages;
+}
+
+static inline int compact_finished(struct zone *zone,
+						struct compact_control *cc)
+{
+	if (fatal_signal_pending(current))
+		return COMPACT_PARTIAL;
+
+	/* Compaction run completes if the migrate and free scanner meet */
+	if (cc->free_pfn <= cc->migrate_pfn)
+		return COMPACT_COMPLETE;
+
+	return COMPACT_INCOMPLETE;
+}
+
+static int compact_zone(struct zone *zone, struct compact_control *cc)
+{
+	int ret;
+
+	/* Setup to move all movable pages to the end of the zone */
+	cc->migrate_pfn = zone->zone_start_pfn;
+	cc->free_pfn = cc->migrate_pfn + zone->spanned_pages;
+	cc->free_pfn &= ~(pageblock_nr_pages-1);
+
+	migrate_prep();
+
+	while ((ret = compact_finished(zone, cc)) == COMPACT_INCOMPLETE) {
+		unsigned long nr_migrate, nr_remaining;
+
+		if (!isolate_migratepages(zone, cc))
+			continue;
+
+		nr_migrate = cc->nr_migratepages;
+		migrate_pages(&cc->migratepages, compaction_alloc,
+						(unsigned long)cc, 0);
+		update_nr_listpages(cc);
+		nr_remaining = cc->nr_migratepages;
+
+		count_vm_event(COMPACTBLOCKS);
+		count_vm_events(COMPACTPAGES, nr_migrate - nr_remaining);
+		if (nr_remaining)
+			count_vm_events(COMPACTPAGEFAILED, nr_remaining);
+
+		/* Release LRU pages not migrated */
+		if (!list_empty(&cc->migratepages)) {
+			putback_lru_pages(&cc->migratepages);
+			cc->nr_migratepages = 0;
+		}
+
+	}
+
+	/* Release free pages and check accounting */
+	cc->nr_freepages -= release_freepages(&cc->freepages);
+	VM_BUG_ON(cc->nr_freepages != 0);
+
+	return ret;
+}
+
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1191,6 +1191,45 @@ void split_page(struct page *page, unsig
 }
 
 /*
+ * Similar to split_page except the page is already free. As this is only
+ * being used for migration, the migratetype of the block also changes.
+ */
+int split_free_page(struct page *page)
+{
+	unsigned int order;
+	unsigned long watermark;
+	struct zone *zone;
+
+	BUG_ON(!PageBuddy(page));
+
+	zone = page_zone(page);
+	order = page_order(page);
+
+	/* Obey watermarks as if the page was being allocated */
+	watermark = low_wmark_pages(zone) + (1 << order);
+	if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
+		return 0;
+
+	/* Remove page from free list */
+	list_del(&page->lru);
+	zone->free_area[order].nr_free--;
+	rmv_page_order(page);
+	__mod_zone_page_state(zone, NR_FREE_PAGES, -(1UL << order));
+
+	/* Split into individual pages */
+	set_page_refcounted(page);
+	split_page(page, order);
+
+	if (order >= pageblock_order - 1) {
+		struct page *endpage = page + (1 << order) - 1;
+		for (; page < endpage; page += pageblock_nr_pages)
+			set_pageblock_migratetype(page, MIGRATE_MOVABLE);
+	}
+
+	return 1 << order;
+}
+
+/*
  * Really, prep_compound_page() should be called from __rmqueue_bulk().  But
  * we cheat by calling it from here, in the order > 0 path.  Saves a branch
  * or two.
diff --git a/mm/vmstat.c b/mm/vmstat.c
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -896,6 +896,11 @@ static const char * const vmstat_text[] 
 	"allocstall",
 
 	"pgrotated",
+
+	"compact_blocks_moved",
+	"compact_pages_moved",
+	"compact_pagemigrate_failed",
+
 #ifdef CONFIG_HUGETLB_PAGE
 	"htlb_buddy_alloc_success",
 	"htlb_buddy_alloc_fail",

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Re: [PATCH 56 of 67] Memory compaction core

[Johannes Weiner]

Andrea,

On Thu, Apr 08, 2010 at 03:51:39AM +0200, Andrea Arcangeli wrote:
> +static unsigned long isolate_migratepages(struct zone *zone,
> +					struct compact_control *cc)
> +{
> +	unsigned long low_pfn, end_pfn;
> +	struct list_head *migratelist = &cc->migratepages;
> +
> +	/* Do not scan outside zone boundaries */
> +	low_pfn = max(cc->migrate_pfn, zone->zone_start_pfn);
> +
> +	/* Only scan within a pageblock boundary */
> +	end_pfn = ALIGN(low_pfn + pageblock_nr_pages, pageblock_nr_pages);
> +
> +	/* Do not cross the free scanner or scan within a memory hole */
> +	if (end_pfn > cc->free_pfn || !pfn_valid(low_pfn)) {
> +		cc->migrate_pfn = end_pfn;
> +		return 0;
> +	}
> +
> +	/*
> +	 * Ensure that there are not too many pages isolated from the LRU
> +	 * list by either parallel reclaimers or compaction. If there are,
> +	 * delay for some time until fewer pages are isolated
> +	 */
> +	while (unlikely(too_many_isolated(zone))) {
> +		congestion_wait(BLK_RW_ASYNC, HZ/10);
> +
> +		if (fatal_signal_pending(current))
> +			return 0;
> +	}
> +
> +	/* Time to isolate some pages for migration */
> +	spin_lock_irq(&zone->lru_lock);
> +	for (; low_pfn < end_pfn; low_pfn++) {
> +		struct page *page;
> +		if (!pfn_valid_within(low_pfn))
> +			continue;
> +
> +		/* Get the page and skip if free */
> +		page = pfn_to_page(low_pfn);
> +		if (PageBuddy(page)) {

Should this be

		if (PageBuddy(page) || PageTransHuge(page)) {

> +			low_pfn += (1 << page_order(page)) - 1;
> +			continue;
> +		}

instead?

> +
> +		/* Try isolate the page */
> +		if (__isolate_lru_page(page, ISOLATE_BOTH, 0) != 0)
> +			continue;
> +
> +		/* Successfully isolated */
> +		del_page_from_lru_list(zone, page, page_lru(page));
> +		list_add(&page->lru, migratelist);
> +		mem_cgroup_del_lru(page);
> +		cc->nr_migratepages++;
> +
> +		/* Avoid isolating too much */
> +		if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
> +			break;
> +	}
> +
> +	acct_isolated(zone, cc);
> +
> +	spin_unlock_irq(&zone->lru_lock);
> +	cc->migrate_pfn = low_pfn;
> +
> +	return cc->nr_migratepages;

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Re: [PATCH 56 of 67] Memory compaction core

[Andrea Arcangeli]

Hi Johannes,

On Thu, Apr 08, 2010 at 06:18:14PM +0200, Johannes Weiner wrote:
> Andrea,
> 
> > +		/* Get the page and skip if free */
> > +		page = pfn_to_page(low_pfn);
> > +		if (PageBuddy(page)) {
> 
> Should this be
> 
> 		if (PageBuddy(page) || PageTransHuge(page)) {
> 
> > +			low_pfn += (1 << page_order(page)) - 1;
> > +			continue;
> > +		}
> 
> instead?

That was the original code (without PageTransHuge) and what you will
find in -mm. But calling page_order crashes because there's only the
lru_lock here (not the zone->lock), so PageBuddy will go away from
under us and it won't be set when page_order is called.

It's a minor optimization so the fix is what I implemented with:

     if (PageBuddy(page))
     	continue;

I also noticed this loop misses the check for PageTransCompound. Your
PageTransHuge check above would make it crash if it touches a tail
page. this scans all pfn so if a order 10 allocation exists in the
system, that could trip on it. PageTransCompound is the right check
and it'll fix Avi's issue.

I'm undecided if it's safe to have PageTransCompound checked before or
after __isolate_lru_page.

Now split_huge_page_refcount clears PG_head/tail gauranteed under
zone->lru_lock so there's zero risk of PageTransCompound to go away
from under us there. In fact we can also check the
compound_order(page) there, safely. It can't go away from under us
(unlike the page_order when PageBuddy is set).

But khugepaged might create hugepages from under us at that
point. While if we run it after __isolate_lru_page we keep khugepaged
away too, because khugepaged has to isolate the pages to collapse
them, and secondly because khugepaged will never touch a page with
pinned page_count.

> 
> > +
> > +		/* Try isolate the page */
> > +		if (__isolate_lru_page(page, ISOLATE_BOTH, 0) != 0)
> > +			continue;
> > +
> > +		/* Successfully isolated */
> > +		del_page_from_lru_list(zone, page, page_lru(page));
> > +		list_add(&page->lru, migratelist);
> > +		mem_cgroup_del_lru(page);
> > +		cc->nr_migratepages++;
> > +
> > +		/* Avoid isolating too much */
> > +		if (cc->nr_migratepages == COMPACT_CLUSTER_MAX)
> > +			break;
> > +	}
> > +
> > +	acct_isolated(zone, cc);
> > +
> > +	spin_unlock_irq(&zone->lru_lock);
> > +	cc->migrate_pfn = low_pfn;
> > +
> > +	return cc->nr_migratepages;
> 

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Re: [PATCH 56 of 67] Memory compaction core

[Andrea Arcangeli]

Hi Johannes,

I think this should fix the inefficiency. What you think?

Still it shouldn't be able to fix any instability. And I'm afraid
it'll hide bugs. Nevertheless this is the correct behavior, it's
pointless to migrate hugepages around even if it is supposed to work
fine and needed by move_pages.

I'm going to commit it to my tree after some testing.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/mm/compaction.c b/mm/compaction.c
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -265,10 +265,34 @@ static unsigned long isolate_migratepage
 		if (PageBuddy(page))
 			continue;
 
+		/*
+		 * __split_huge_page_refcount() runs with the
+		 * zone->lru_lock held so PG_head can't go away from
+		 * under us. We use PageTransCompound because
+		 * PageTransHuge would VM_BUG_ON if it runs into some
+		 * random tail page that doesn't belong to transparent
+		 * hugepage subsystem during the pfn scan.
+		 */
+		if (PageTransCompound(page)) {
+			low_pfn += (1 << page_order(page)) - 1;
+			continue;
+		}
+
 		/* Try isolate the page */
 		if (__isolate_lru_page(page, ISOLATE_BOTH, 0) != 0)
 			continue;
 
+		/*
+		 * khugepaged cannot generate an hugepage queued into
+		 * the LRU before __isolate_lru_page runs, because
+		 * it has to take the zone->lru_lock first in order to
+		 * set PageLRU onto the hugepage. And PageHead is always
+		 * set by the buddy allocator before returning the hugepage
+		 * to khugepaged and in turn before taking the lru_lock
+		 * to set PageLRU.
+		 */
+		BUG_ON(PageTransCompound(page));
+
 		/* Successfully isolated */
 		del_page_from_lru_list(zone, page, page_lru(page));
 		list_add(&page->lru, migratelist);

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Re: [PATCH 56 of 67] Memory compaction core

[Andrea Arcangeli]

On Thu, Apr 08, 2010 at 07:09:48PM +0200, Andrea Arcangeli wrote:
> +		if (PageTransCompound(page)) {
> +			low_pfn += (1 << page_order(page)) - 1;
> +			continue;
> +		}

Thinking again the low_pfn += I'll have to remove it even from the
hugepage case, because this could be a compound page that doesn't
belong to transparent hugepage support, so it could go away from under
us and make the order-reading invalid despite we hold the lru_lock.

Unless we mark the transparent hugepages with a special bit in the
page->flags we can't retain this optimization.

This would have been safe if we used compound_order and we knew it was
owned by transparent hugepage support. Given how short we are in
page->flags (I already had to remove the PG_buddy) it's unlikely we
can mark it specially and retain this.

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Re: [PATCH 56 of 67] Memory compaction core

[Johannes Weiner]

On Thu, Apr 08, 2010 at 07:14:58PM +0200, Andrea Arcangeli wrote:
> On Thu, Apr 08, 2010 at 07:09:48PM +0200, Andrea Arcangeli wrote:
> > +		if (PageTransCompound(page)) {
> > +			low_pfn += (1 << page_order(page)) - 1;
> > +			continue;
> > +		}
> 
> Thinking again the low_pfn += I'll have to remove it even from the
> hugepage case, because this could be a compound page that doesn't
> belong to transparent hugepage support, so it could go away from under
> us and make the order-reading invalid despite we hold the lru_lock.

Compared to _splitting_ huge pages, it's already an improvement, even
without the clever skipping :-)

> Unless we mark the transparent hugepages with a special bit in the
> page->flags we can't retain this optimization.
> 
> This would have been safe if we used compound_order and we knew it was
> owned by transparent hugepage support. Given how short we are in
> page->flags (I already had to remove the PG_buddy) it's unlikely we
> can mark it specially and retain this.

Humm, maybe the start pfn could be huge page aligned?  That would make
it possible to check for PageTransHuge() and skip over compound_order()
pages.  This way, we should never actually run into PG_tail pages.

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Re: [PATCH 56 of 67] Memory compaction core

[Andrea Arcangeli]

On Thu, Apr 08, 2010 at 07:56:04PM +0200, Johannes Weiner wrote:
> Humm, maybe the start pfn could be huge page aligned?  That would make
> it possible to check for PageTransHuge() and skip over compound_order()
> pages.  This way, we should never actually run into PG_tail pages.

The problem here are random compound pages that aren't owned by the
transparent hugepage subsystem. If we can't identify those, it's
unsafe to call compound_order (like it's unsafe to call page_order for
pagebuddy pages).

I don't see a way to solve this without a new PG_ bitflag. We could do
a 64-bit only optimization though... ;)

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Re: [PATCH 56 of 67] Memory compaction core

[Johannes Weiner]

On Thu, Apr 08, 2010 at 07:58:47PM +0200, Andrea Arcangeli wrote:
> On Thu, Apr 08, 2010 at 07:56:04PM +0200, Johannes Weiner wrote:
> > Humm, maybe the start pfn could be huge page aligned?  That would make
> > it possible to check for PageTransHuge() and skip over compound_order()
> > pages.  This way, we should never actually run into PG_tail pages.
> 
> The problem here are random compound pages that aren't owned by the
> transparent hugepage subsystem. If we can't identify those, it's
> unsafe to call compound_order (like it's unsafe to call page_order for
> pagebuddy pages).

But transparent huge pages are the only compound pages on the LRU, so
we should be able to identify them.

The lru_lock excludes isolation, splitting and collapsing, so I think
this is safe:

	if (PageLRU() && PageTransCompound()) {
		low_pfn += (1 << compound_order()) - 1
		continue
	}

	if (__isolate_lru_page())
		continue

	...

Do I still miss something?  If so, I will shut up now :-)

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Re: [PATCH 56 of 67] Memory compaction core

[Andrea Arcangeli]

On Thu, Apr 08, 2010 at 08:48:42PM +0200, Johannes Weiner wrote:
> On Thu, Apr 08, 2010 at 07:58:47PM +0200, Andrea Arcangeli wrote:
> > On Thu, Apr 08, 2010 at 07:56:04PM +0200, Johannes Weiner wrote:
> > > Humm, maybe the start pfn could be huge page aligned?  That would make
> > > it possible to check for PageTransHuge() and skip over compound_order()
> > > pages.  This way, we should never actually run into PG_tail pages.
> > 
> > The problem here are random compound pages that aren't owned by the
> > transparent hugepage subsystem. If we can't identify those, it's
> > unsafe to call compound_order (like it's unsafe to call page_order for
> > pagebuddy pages).
> 
> But transparent huge pages are the only compound pages on the LRU, so
> we should be able to identify them.
> 
> The lru_lock excludes isolation, splitting and collapsing, so I think
> this is safe:
> 
> 	if (PageLRU() && PageTransCompound()) {
> 		low_pfn += (1 << compound_order()) - 1
> 		continue
> 	}
> 
> 	if (__isolate_lru_page())
> 		continue
> 
> 	...

I don't see anything wrong with this. You're right lru_lock excludes
isolation, splitting and collapsing (collapsing if it's pagelru it
means it already happened).

Thanks for thinking this optimization in detail. I guess retaining the
other optimization will be harder. It depends how costly it is to take
the zone->lock, the main annoyance is that we can only do that if we
release the lru_lock first or we get lock inversion deadlocks. So it
costs 4 locked ops to skip max 1024 pages (but in average it'll be
much less than 1024 pages, more like 128 [no math just random guess]
when there's quite some ram free).

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Re: [PATCH 56 of 67] Memory compaction core

[Andrea Arcangeli]

Hi Johannes,

I changed it like this.

-------
Subject: transhuge isolate_migratepages()

From: Andrea Arcangeli <aarcange@redhat.com>

It's not worth migrating transparent hugepages during compaction. Those
hugepages don't create fragmentation.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/mm/compaction.c b/mm/compaction.c
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -265,10 +265,23 @@ static unsigned long isolate_migratepage
 		if (PageBuddy(page))
 			continue;
 
+		if (!PageLRU(page))
+			continue;
+
+		/*
+		 * PageLRU is set, and lru_lock excludes isolation,
+		 * splitting and collapsing (collapsing has already
+		 * happened if PageLRU is set).
+		 */
+		if (PageTransHuge(page))
+			continue;
+
 		/* Try isolate the page */
 		if (__isolate_lru_page(page, ISOLATE_BOTH, 0) != 0)
 			continue;
 
+		VM_BUG_ON(PageTransCompound(page));
+
 		/* Successfully isolated */
 		del_page_from_lru_list(zone, page, page_lru(page));
 		list_add(&page->lru, migratelist);


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Re: [PATCH 56 of 67] Memory compaction core

[Mel Gorman]

On Thu, Apr 08, 2010 at 11:23:32PM +0200, Andrea Arcangeli wrote:
> On Thu, Apr 08, 2010 at 08:48:42PM +0200, Johannes Weiner wrote:
> > On Thu, Apr 08, 2010 at 07:58:47PM +0200, Andrea Arcangeli wrote:
> > > On Thu, Apr 08, 2010 at 07:56:04PM +0200, Johannes Weiner wrote:
> > > > Humm, maybe the start pfn could be huge page aligned?  That would make
> > > > it possible to check for PageTransHuge() and skip over compound_order()
> > > > pages.  This way, we should never actually run into PG_tail pages.
> > > 
> > > The problem here are random compound pages that aren't owned by the
> > > transparent hugepage subsystem. If we can't identify those, it's
> > > unsafe to call compound_order (like it's unsafe to call page_order for
> > > pagebuddy pages).
> > 
> > But transparent huge pages are the only compound pages on the LRU, so
> > we should be able to identify them.
> > 
> > The lru_lock excludes isolation, splitting and collapsing, so I think
> > this is safe:
> > 
> > 	if (PageLRU() && PageTransCompound()) {
> > 		low_pfn += (1 << compound_order()) - 1
> > 		continue
> > 	}
> > 
> > 	if (__isolate_lru_page())
> > 		continue
> > 
> > 	...
> 
> I don't see anything wrong with this. You're right lru_lock excludes
> isolation, splitting and collapsing (collapsing if it's pagelru it
> means it already happened).
> 
> Thanks for thinking this optimization in detail. I guess retaining the
> other optimization will be harder. It depends how costly it is to take
> the zone->lock, the main annoyance is that we can only do that if we
> release the lru_lock first or we get lock inversion deadlocks.

I would find it very difficult to justify the cost of dropping one lock
and taking the other myself. It's potentially stalling other allocators for
order-0 pages (i.e. per-cpu refill) so that direct compaction for high-order
pages can go very slightly faster. 

> So it
> costs 4 locked ops to skip max 1024 pages (but in average it'll be
> much less than 1024 pages, more like 128 [no math just random guess]
> when there's quite some ram free).
> 

4 irq-safe locked ops. I don't know off-hand what the cycle cost of disabling
and enabling IRQs is but I'd expect it to be longer than what it takes to
scan over a few pages.

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab

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Re: [PATCH 56 of 67] Memory compaction core

[Andrea Arcangeli]

On Fri, Apr 09, 2010 at 11:51:27AM +0100, Mel Gorman wrote:
> 4 irq-safe locked ops. I don't know off-hand what the cycle cost of disabling
> and enabling IRQs is but I'd expect it to be longer than what it takes to
> scan over a few pages.

Agreed.

BTW, after the #19 release the rmap_mapcount != page_mapcount error
that triggered also without memory compaction never happened again, so
that error was most certainly caused by the anon-vma changes, that I
backed out in #19 (as the fixes didn't work yet for me).

The bug in remove_migration_pte happened again once but this time I
tracked it down and fixed. rmap_walk will have lookup in parent or
child vmas that may have been cowed and collapsed by khugepaged.

You can find this already in 8707120d97e7052ffb45f9879efce8e7bd361711
in aa.git (soon I'll post a -20 release, I wanted to add numa
awareness to alloc_hugepage first). I've been running with
8707120d97e7052ffb45f9879efce8e7bd361711 with heavy load on multiple
systems with memory compaction enabled in direct reclaim of hugepage
faults, and there's zero problem. So we're fully stable now (again).

diff --git a/mm/migrate.c b/mm/migrate.c
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -100,6 +100,13 @@ static int remove_migration_pte(struct p
 		goto out;
 
 	pmd = pmd_offset(pud, addr);
+	if (pmd_trans_huge(*pmd)) {
+		/* verify this pmd isn't mapping our old page */
+		BUG_ON(!pmd_present(*pmd));
+		BUG_ON(PageTransCompound(old));
+		BUG_ON(pmd_page(*pmd) == old);
+		goto out;
+	}
 	if (!pmd_present(*pmd))
 		goto out;
 

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[PATCH 57 of 67] Add /proc trigger for memory compaction

[Andrea Arcangeli]

From: Mel Gorman <mel@csn.ul.ie>

This patch adds a proc file /proc/sys/vm/compact_memory. When an arbitrary
value is written to the file, all zones are compacted. The expected user
of such a trigger is a job scheduler that prepares the system before the
target application runs.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
---

diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -19,6 +19,7 @@ files can be found in mm/swap.c.
 Currently, these files are in /proc/sys/vm:
 
 - block_dump
+- compact_memory
 - dirty_background_bytes
 - dirty_background_ratio
 - dirty_bytes
@@ -64,6 +65,15 @@ information on block I/O debugging is in
 
 ==============================================================
 
+compact_memory
+
+Available only when CONFIG_COMPACTION is set. When 1 is written to the file,
+all zones are compacted such that free memory is available in contiguous
+blocks where possible. This can be important for example in the allocation of
+huge pages although processes will also directly compact memory as required.
+
+==============================================================
+
 dirty_background_bytes
 
 Contains the amount of dirty memory at which the pdflush background writeback
diff --git a/include/linux/compaction.h b/include/linux/compaction.h
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -6,4 +6,10 @@
 #define COMPACT_PARTIAL		1
 #define COMPACT_COMPLETE	2
 
+#ifdef CONFIG_COMPACTION
+extern int sysctl_compact_memory;
+extern int sysctl_compaction_handler(struct ctl_table *table, int write,
+			void __user *buffer, size_t *length, loff_t *ppos);
+#endif /* CONFIG_COMPACTION */
+
 #endif /* _LINUX_COMPACTION_H */
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -52,6 +52,7 @@
 #include <linux/slow-work.h>
 #include <linux/perf_event.h>
 #include <linux/kprobes.h>
+#include <linux/compaction.h>
 
 #include <asm/uaccess.h>
 #include <asm/processor.h>
@@ -1099,6 +1100,15 @@ static struct ctl_table vm_table[] = {
 		.mode		= 0644,
 		.proc_handler	= drop_caches_sysctl_handler,
 	},
+#ifdef CONFIG_COMPACTION
+	{
+		.procname	= "compact_memory",
+		.data		= &sysctl_compact_memory,
+		.maxlen		= sizeof(int),
+		.mode		= 0200,
+		.proc_handler	= sysctl_compaction_handler,
+	},
+#endif /* CONFIG_COMPACTION */
 	{
 		.procname	= "min_free_kbytes",
 		.data		= &min_free_kbytes,
diff --git a/mm/compaction.c b/mm/compaction.c
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -12,6 +12,7 @@
 #include <linux/compaction.h>
 #include <linux/mm_inline.h>
 #include <linux/backing-dev.h>
+#include <linux/sysctl.h>
 #include "internal.h"
 
 /*
@@ -332,7 +333,7 @@ static void update_nr_listpages(struct c
 	cc->nr_freepages = nr_freepages;
 }
 
-static inline int compact_finished(struct zone *zone,
+static int compact_finished(struct zone *zone,
 						struct compact_control *cc)
 {
 	if (fatal_signal_pending(current))
@@ -388,3 +389,63 @@ static int compact_zone(struct zone *zon
 	return ret;
 }
 
+/* Compact all zones within a node */
+static int compact_node(int nid)
+{
+	int zoneid;
+	pg_data_t *pgdat;
+	struct zone *zone;
+
+	if (nid < 0 || nid >= nr_node_ids || !node_online(nid))
+		return -EINVAL;
+	pgdat = NODE_DATA(nid);
+
+	/* Flush pending updates to the LRU lists */
+	lru_add_drain_all();
+
+	for (zoneid = 0; zoneid < MAX_NR_ZONES; zoneid++) {
+		struct compact_control cc = {
+			.nr_freepages = 0,
+			.nr_migratepages = 0,
+		};
+
+		zone = &pgdat->node_zones[zoneid];
+		if (!populated_zone(zone))
+			continue;
+
+		cc.zone = zone,
+		INIT_LIST_HEAD(&cc.freepages);
+		INIT_LIST_HEAD(&cc.migratepages);
+
+		compact_zone(zone, &cc);
+
+		VM_BUG_ON(!list_empty(&cc.freepages));
+		VM_BUG_ON(!list_empty(&cc.migratepages));
+	}
+
+	return 0;
+}
+
+/* Compact all nodes in the system */
+static int compact_nodes(void)
+{
+	int nid;
+
+	for_each_online_node(nid)
+		compact_node(nid);
+
+	return COMPACT_COMPLETE;
+}
+
+/* The written value is actually unused, all memory is compacted */
+int sysctl_compact_memory;
+
+/* This is the entry point for compacting all nodes via /proc/sys/vm */
+int sysctl_compaction_handler(struct ctl_table *table, int write,
+			void __user *buffer, size_t *length, loff_t *ppos)
+{
+	if (write)
+		return compact_nodes();
+
+	return 0;
+}

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[PATCH 58 of 67] Add /sys trigger for per-node memory compaction

[Andrea Arcangeli]

From: Mel Gorman <mel@csn.ul.ie>

This patch adds a per-node sysfs file called compact. When the file is
written to, each zone in that node is compacted. The intention that this
would be used by something like a job scheduler in a batch system before
a job starts so that the job can allocate the maximum number of
hugepages without significant start-up cost.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---

diff --git a/Documentation/ABI/testing/sysfs-devices-node b/Documentation/ABI/testing/sysfs-devices-node
new file mode 100644
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices-node
@@ -0,0 +1,7 @@
+What:		/sys/devices/system/node/nodeX/compact
+Date:		February 2010
+Contact:	Mel Gorman <mel@csn.ul.ie>
+Description:
+		When this file is written to, all memory within that node
+		will be compacted. When it completes, memory will be freed
+		into blocks which have as many contiguous pages as possible
diff --git a/drivers/base/node.c b/drivers/base/node.c
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -16,6 +16,7 @@
 #include <linux/device.h>
 #include <linux/swap.h>
 #include <linux/slab.h>
+#include <linux/compaction.h>
 
 static struct sysdev_class_attribute *node_state_attrs[];
 
@@ -246,6 +247,8 @@ int register_node(struct node *node, int
 		scan_unevictable_register_node(node);
 
 		hugetlb_register_node(node);
+
+		compaction_register_node(node);
 	}
 	return error;
 }
diff --git a/include/linux/compaction.h b/include/linux/compaction.h
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -12,4 +12,20 @@ extern int sysctl_compaction_handler(str
 			void __user *buffer, size_t *length, loff_t *ppos);
 #endif /* CONFIG_COMPACTION */
 
+#if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
+extern int compaction_register_node(struct node *node);
+extern void compaction_unregister_node(struct node *node);
+
+#else
+
+static inline int compaction_register_node(struct node *node)
+{
+	return 0;
+}
+
+static inline void compaction_unregister_node(struct node *node)
+{
+}
+#endif /* CONFIG_COMPACTION && CONFIG_SYSFS && CONFIG_NUMA */
+
 #endif /* _LINUX_COMPACTION_H */
diff --git a/mm/compaction.c b/mm/compaction.c
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -13,6 +13,7 @@
 #include <linux/mm_inline.h>
 #include <linux/backing-dev.h>
 #include <linux/sysctl.h>
+#include <linux/sysfs.h>
 #include "internal.h"
 
 /*
@@ -449,3 +450,25 @@ int sysctl_compaction_handler(struct ctl
 
 	return 0;
 }
+
+#if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
+ssize_t sysfs_compact_node(struct sys_device *dev,
+			struct sysdev_attribute *attr,
+			const char *buf, size_t count)
+{
+	compact_node(dev->id);
+
+	return count;
+}
+static SYSDEV_ATTR(compact, S_IWUSR, NULL, sysfs_compact_node);
+
+int compaction_register_node(struct node *node)
+{
+	return sysdev_create_file(&node->sysdev, &attr_compact);
+}
+
+void compaction_unregister_node(struct node *node)
+{
+	return sysdev_remove_file(&node->sysdev, &attr_compact);
+}
+#endif /* CONFIG_SYSFS && CONFIG_NUMA */

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[PATCH 59 of 67] Direct compact when a high-order allocation fails

[Andrea Arcangeli]

From: Mel Gorman <mel@csn.ul.ie>

Ordinarily when a high-order allocation fails, direct reclaim is entered to
free pages to satisfy the allocation.  With this patch, it is determined if
an allocation failed due to external fragmentation instead of low memory
and if so, the calling process will compact until a suitable page is
freed. Compaction by moving pages in memory is considerably cheaper than
paging out to disk and works where there are locked pages or no swap. If
compaction fails to free a page of a suitable size, then reclaim will
still occur.

Direct compaction returns as soon as possible. As each block is compacted,
it is checked if a suitable page has been freed and if so, it returns.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
---

diff --git a/include/linux/compaction.h b/include/linux/compaction.h
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -1,15 +1,27 @@
 #ifndef _LINUX_COMPACTION_H
 #define _LINUX_COMPACTION_H
 
-/* Return values for compact_zone() */
-#define COMPACT_INCOMPLETE	0
-#define COMPACT_PARTIAL		1
-#define COMPACT_COMPLETE	2
+/* Return values for compact_zone() and try_to_compact_pages() */
+#define COMPACT_SKIPPED		0
+#define COMPACT_INCOMPLETE	1
+#define COMPACT_PARTIAL		2
+#define COMPACT_COMPLETE	3
 
 #ifdef CONFIG_COMPACTION
 extern int sysctl_compact_memory;
 extern int sysctl_compaction_handler(struct ctl_table *table, int write,
 			void __user *buffer, size_t *length, loff_t *ppos);
+
+extern int fragmentation_index(struct zone *zone, unsigned int order);
+extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
+			int order, gfp_t gfp_mask, nodemask_t *mask);
+#else
+static inline unsigned long try_to_compact_pages(struct zonelist *zonelist,
+			int order, gfp_t gfp_mask, nodemask_t *nodemask)
+{
+	return COMPACT_INCOMPLETE;
+}
+
 #endif /* CONFIG_COMPACTION */
 
 #if defined(CONFIG_COMPACTION) && defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -44,6 +44,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
 		KSWAPD_SKIP_CONGESTION_WAIT,
 		PAGEOUTRUN, ALLOCSTALL, PGROTATED,
 		COMPACTBLOCKS, COMPACTPAGES, COMPACTPAGEFAILED,
+		COMPACTSTALL, COMPACTFAIL, COMPACTSUCCESS,
 #ifdef CONFIG_HUGETLB_PAGE
 		HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
 #endif
diff --git a/mm/compaction.c b/mm/compaction.c
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -35,6 +35,8 @@ struct compact_control {
 	unsigned long nr_anon;
 	unsigned long nr_file;
 
+	unsigned int order;		/* order a direct compactor needs */
+	int migratetype;		/* MOVABLE, RECLAIMABLE etc */
 	struct zone *zone;
 };
 
@@ -337,6 +339,9 @@ static void update_nr_listpages(struct c
 static int compact_finished(struct zone *zone,
 						struct compact_control *cc)
 {
+	unsigned int order;
+	unsigned long watermark = low_wmark_pages(zone) + (1 << cc->order);
+
 	if (fatal_signal_pending(current))
 		return COMPACT_PARTIAL;
 
@@ -344,6 +349,24 @@ static int compact_finished(struct zone 
 	if (cc->free_pfn <= cc->migrate_pfn)
 		return COMPACT_COMPLETE;
 
+	/* Compaction run is not finished if the watermark is not met */
+	if (!zone_watermark_ok(zone, cc->order, watermark, 0, 0))
+		return COMPACT_INCOMPLETE;
+
+	if (cc->order == -1)
+		return COMPACT_INCOMPLETE;
+
+	/* Direct compactor: Is a suitable page free? */
+	for (order = cc->order; order < MAX_ORDER; order++) {
+		/* Job done if page is free of the right migratetype */
+		if (!list_empty(&zone->free_area[order].free_list[cc->migratetype]))
+			return COMPACT_PARTIAL;
+
+		/* Job done if allocation would set block type */
+		if (order >= pageblock_order && zone->free_area[order].nr_free)
+			return COMPACT_PARTIAL;
+	}
+
 	return COMPACT_INCOMPLETE;
 }
 
@@ -390,6 +413,99 @@ static int compact_zone(struct zone *zon
 	return ret;
 }
 
+static unsigned long compact_zone_order(struct zone *zone,
+						int order, gfp_t gfp_mask)
+{
+	struct compact_control cc = {
+		.nr_freepages = 0,
+		.nr_migratepages = 0,
+		.order = order,
+		.migratetype = allocflags_to_migratetype(gfp_mask),
+		.zone = zone,
+	};
+	INIT_LIST_HEAD(&cc.freepages);
+	INIT_LIST_HEAD(&cc.migratepages);
+
+	return compact_zone(zone, &cc);
+}
+
+/**
+ * try_to_compact_pages - Direct compact to satisfy a high-order allocation
+ * @zonelist: The zonelist used for the current allocation
+ * @order: The order of the current allocation
+ * @gfp_mask: The GFP mask of the current allocation
+ * @nodemask: The allowed nodes to allocate from
+ *
+ * This is the main entry point for direct page compaction.
+ */
+unsigned long try_to_compact_pages(struct zonelist *zonelist,
+			int order, gfp_t gfp_mask, nodemask_t *nodemask)
+{
+	enum zone_type high_zoneidx = gfp_zone(gfp_mask);
+	int may_enter_fs = gfp_mask & __GFP_FS;
+	int may_perform_io = gfp_mask & __GFP_IO;
+	unsigned long watermark;
+	struct zoneref *z;
+	struct zone *zone;
+	int rc = COMPACT_SKIPPED;
+
+	/*
+	 * Check whether it is worth even starting compaction. The order check is
+	 * made because an assumption is made that the page allocator can satisfy
+	 * the "cheaper" orders without taking special steps
+	 */
+	if (order <= PAGE_ALLOC_COSTLY_ORDER || !may_enter_fs || !may_perform_io)
+		return rc;
+
+	count_vm_event(COMPACTSTALL);
+
+	/* Compact each zone in the list */
+	for_each_zone_zonelist_nodemask(zone, z, zonelist, high_zoneidx,
+								nodemask) {
+		int fragindex;
+		int status;
+
+		/*
+		 * Watermarks for order-0 must be met for compaction. Note
+		 * the 2UL. This is because during migration, copies of
+		 * pages need to be allocated and for a short time, the
+		 * footprint is higher
+		 */
+		watermark = low_wmark_pages(zone) + (2UL << order);
+		if (!zone_watermark_ok(zone, 0, watermark, 0, 0))
+			continue;
+
+		/*
+		 * fragmentation index determines if allocation failures are
+		 * due to low memory or external fragmentation
+		 *
+		 * index of -1 implies allocations might succeed depending
+		 * 	on watermarks
+		 * index towards 0 implies failure is due to lack of memory
+		 * index towards 1000 implies failure is due to fragmentation
+		 *
+		 * Only compact if a failure would be due to fragmentation.
+		 */
+		fragindex = fragmentation_index(zone, order);
+		if (fragindex >= 0 && fragindex <= 500)
+			continue;
+
+		if (fragindex == -1 && zone_watermark_ok(zone, order, watermark, 0, 0)) {
+			rc = COMPACT_PARTIAL;
+			break;
+		}
+
+		status = compact_zone_order(zone, order, gfp_mask);
+		rc = max(status, rc);
+
+		if (zone_watermark_ok(zone, order, watermark, 0, 0))
+			break;
+	}
+
+	return rc;
+}
+
+
 /* Compact all zones within a node */
 static int compact_node(int nid)
 {
@@ -408,6 +524,7 @@ static int compact_node(int nid)
 		struct compact_control cc = {
 			.nr_freepages = 0,
 			.nr_migratepages = 0,
+			.order = -1,
 		};
 
 		zone = &pgdat->node_zones[zoneid];
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -49,6 +49,7 @@
 #include <linux/debugobjects.h>
 #include <linux/kmemleak.h>
 #include <linux/memory.h>
+#include <linux/compaction.h>
 #include <trace/events/kmem.h>
 #include <linux/ftrace_event.h>
 
@@ -1748,6 +1749,36 @@ __alloc_pages_direct_reclaim(gfp_t gfp_m
 
 	cond_resched();
 
+	/* Try memory compaction for high-order allocations before reclaim */
+	if (order) {
+		*did_some_progress = try_to_compact_pages(zonelist,
+						order, gfp_mask, nodemask);
+		if (*did_some_progress != COMPACT_SKIPPED) {
+
+			/* Page migration frees to the PCP lists but we want merging */
+			drain_pages(get_cpu());
+			put_cpu();
+
+			page = get_page_from_freelist(gfp_mask, nodemask,
+					order, zonelist, high_zoneidx,
+					alloc_flags, preferred_zone,
+					migratetype);
+			if (page) {
+				__count_vm_event(COMPACTSUCCESS);
+				return page;
+			}
+
+			/*
+			 * It's bad if compaction run occurs and fails.
+			 * The most likely reason is that pages exist,
+			 * but not enough to satisfy watermarks.
+			 */
+			count_vm_event(COMPACTFAIL);
+
+			cond_resched();
+		}
+	}
+
 	/* We now go into synchronous reclaim */
 	cpuset_memory_pressure_bump();
 	p->flags |= PF_MEMALLOC;
diff --git a/mm/vmstat.c b/mm/vmstat.c
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -562,7 +562,7 @@ static int unusable_show(struct seq_file
  * The value can be used to determine if page reclaim or compaction
  * should be used
  */
-int fragmentation_index(unsigned int order, struct contig_page_info *info)
+int __fragmentation_index(unsigned int order, struct contig_page_info *info)
 {
 	unsigned long requested = 1UL << order;
 
@@ -582,6 +582,14 @@ int fragmentation_index(unsigned int ord
 	return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
 }
 
+/* Same as __fragmentation index but allocs contig_page_info on stack */
+int fragmentation_index(struct zone *zone, unsigned int order)
+{
+	struct contig_page_info info;
+
+	fill_contig_page_info(zone, order, &info);
+	return __fragmentation_index(order, &info);
+}
 
 static void extfrag_show_print(struct seq_file *m,
 					pg_data_t *pgdat, struct zone *zone)
@@ -597,7 +605,7 @@ static void extfrag_show_print(struct se
 				zone->name);
 	for (order = 0; order < MAX_ORDER; ++order) {
 		fill_contig_page_info(zone, order, &info);
-		index = fragmentation_index(order, &info);
+		index = __fragmentation_index(order, &info);
 		seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
 	}
 
@@ -900,6 +908,9 @@ static const char * const vmstat_text[] 
 	"compact_blocks_moved",
 	"compact_pages_moved",
 	"compact_pagemigrate_failed",
+	"compact_stall",
+	"compact_fail",
+	"compact_success",
 
 #ifdef CONFIG_HUGETLB_PAGE
 	"htlb_buddy_alloc_success",

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[PATCH 60 of 67] Add a tunable that decides when memory should be compacted and when it should be reclaimed

[Andrea Arcangeli]

From: Mel Gorman <mel@csn.ul.ie>

The kernel applies some heuristics when deciding if memory should be
compacted or reclaimed to satisfy a high-order allocation. One of these
is based on the fragmentation. If the index is below 500, memory will
not be compacted. This choice is arbitrary and not based on data. To
help optimise the system and set a sensible default for this value, this
patch adds a sysctl extfrag_threshold. The kernel will only compact
memory if the fragmentation index is above the extfrag_threshold.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
---

diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -27,6 +27,7 @@ Currently, these files are in /proc/sys/
 - dirty_ratio
 - dirty_writeback_centisecs
 - drop_caches
+- extfrag_threshold
 - hugepages_treat_as_movable
 - hugetlb_shm_group
 - laptop_mode
@@ -130,8 +131,7 @@ 100'ths of a second.
 
 Setting this to zero disables periodic writeback altogether.
 
-==============================================================
-
+============================================================== 
 drop_caches
 
 Writing to this will cause the kernel to drop clean caches, dentries and
@@ -149,6 +149,20 @@ user should run `sync' first.
 
 ==============================================================
 
+extfrag_threshold
+
+This parameter affects whether the kernel will compact memory or direct
+reclaim to satisfy a high-order allocation. /proc/extfrag_index shows what
+the fragmentation index for each order is in each zone in the system. Values
+tending towards 0 imply allocations would fail due to lack of memory,
+values towards 1000 imply failures are due to fragmentation and -1 implies
+that the allocation will succeed as long as watermarks are met.
+
+The kernel will not compact memory in a zone if the
+fragmentation index is <= extfrag_threshold. The default value is 500.
+
+==============================================================
+
 hugepages_treat_as_movable
 
 This parameter is only useful when kernelcore= is specified at boot time to
diff --git a/include/linux/compaction.h b/include/linux/compaction.h
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -11,6 +11,9 @@
 extern int sysctl_compact_memory;
 extern int sysctl_compaction_handler(struct ctl_table *table, int write,
 			void __user *buffer, size_t *length, loff_t *ppos);
+extern int sysctl_extfrag_threshold;
+extern int sysctl_extfrag_handler(struct ctl_table *table, int write,
+			void __user *buffer, size_t *length, loff_t *ppos);
 
 extern int fragmentation_index(struct zone *zone, unsigned int order);
 extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -241,6 +241,11 @@ static int min_sched_shares_ratelimit = 
 static int max_sched_shares_ratelimit = NSEC_PER_SEC; /* 1 second */
 #endif
 
+#ifdef CONFIG_COMPACTION
+static int min_extfrag_threshold = 0;
+static int max_extfrag_threshold = 1000;
+#endif
+
 static struct ctl_table kern_table[] = {
 	{
 		.procname	= "sched_child_runs_first",
@@ -1108,6 +1113,16 @@ static struct ctl_table vm_table[] = {
 		.mode		= 0200,
 		.proc_handler	= sysctl_compaction_handler,
 	},
+	{
+		.procname	= "extfrag_threshold",
+		.data		= &sysctl_extfrag_threshold,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= sysctl_extfrag_handler,
+		.extra1		= &min_extfrag_threshold,
+		.extra2		= &max_extfrag_threshold,
+	},
+
 #endif /* CONFIG_COMPACTION */
 	{
 		.procname	= "min_free_kbytes",
diff --git a/mm/compaction.c b/mm/compaction.c
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -429,6 +429,8 @@ static unsigned long compact_zone_order(
 	return compact_zone(zone, &cc);
 }
 
+int sysctl_extfrag_threshold = 500;
+
 /**
  * try_to_compact_pages - Direct compact to satisfy a high-order allocation
  * @zonelist: The zonelist used for the current allocation
@@ -487,7 +489,7 @@ unsigned long try_to_compact_pages(struc
 		 * Only compact if a failure would be due to fragmentation.
 		 */
 		fragindex = fragmentation_index(zone, order);
-		if (fragindex >= 0 && fragindex <= 500)
+		if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
 			continue;
 
 		if (fragindex == -1 && zone_watermark_ok(zone, order, watermark, 0, 0)) {
@@ -568,6 +570,14 @@ int sysctl_compaction_handler(struct ctl
 	return 0;
 }
 
+int sysctl_extfrag_handler(struct ctl_table *table, int write,
+			void __user *buffer, size_t *length, loff_t *ppos)
+{
+	proc_dointvec_minmax(table, write, buffer, length, ppos);
+
+	return 0;
+}
+
 #if defined(CONFIG_SYSFS) && defined(CONFIG_NUMA)
 ssize_t sysfs_compact_node(struct sys_device *dev,
 			struct sysdev_attribute *attr,

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[PATCH 61 of 67] Allow the migration of PageSwapCache pages

[Andrea Arcangeli]

From: Mel Gorman <mel@csn.ul.ie>

PageAnon pages that are unmapped may or may not have an anon_vma so are
not currently migrated. However, a swap cache page can be migrated and
fits this description. This patch identifies page swap caches and allows
them to be migrated but ensures that no attempt to made to remap the pages
would would potentially try to access an already freed anon_vma.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
---

diff --git a/mm/migrate.c b/mm/migrate.c
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -491,7 +491,8 @@ static int fallback_migrate_page(struct 
  *   < 0 - error code
  *  == 0 - success
  */
-static int move_to_new_page(struct page *newpage, struct page *page)
+static int move_to_new_page(struct page *newpage, struct page *page,
+						int remap_swapcache)
 {
 	struct address_space *mapping;
 	int rc;
@@ -526,10 +527,12 @@ static int move_to_new_page(struct page 
 	else
 		rc = fallback_migrate_page(mapping, newpage, page);
 
-	if (!rc)
-		remove_migration_ptes(page, newpage);
-	else
+	if (rc) {
 		newpage->mapping = NULL;
+	} else {
+		if (remap_swapcache) 
+			remove_migration_ptes(page, newpage);
+	}
 
 	unlock_page(newpage);
 
@@ -546,6 +549,7 @@ static int unmap_and_move(new_page_t get
 	int rc = 0;
 	int *result = NULL;
 	struct page *newpage = get_new_page(page, private, &result);
+	int remap_swapcache = 1;
 	int rcu_locked = 0;
 	int charge = 0;
 	struct mem_cgroup *mem = NULL;
@@ -610,18 +614,33 @@ static int unmap_and_move(new_page_t get
 		rcu_read_lock();
 		rcu_locked = 1;
 
-		/*
-		 * If the page has no mappings any more, just bail. An
-		 * unmapped anon page is likely to be freed soon but worse,
-		 * it's possible its anon_vma disappeared between when
-		 * the page was isolated and when we reached here while
-		 * the RCU lock was not held
-		 */
-		if (!page_mapped(page))
-			goto rcu_unlock;
+		/* Determine how to safely use anon_vma */
+		if (!page_mapped(page)) {
+			if (!PageSwapCache(page))
+				goto rcu_unlock;
 
-		anon_vma = page_anon_vma(page);
-		atomic_inc(&anon_vma->external_refcount);
+			/*
+			 * We cannot be sure that the anon_vma of an unmapped
+			 * swapcache page is safe to use because we don't
+			 * know in advance if the VMA that this page belonged
+			 * to still exists. If the VMA and others sharing the
+			 * data have been freed, then the anon_vma could
+			 * already be invalid.
+			 *
+			 * To avoid this possibility, swapcache pages get
+			 * migrated but are not remapped when migration
+			 * completes
+			 */
+			remap_swapcache = 0;
+		} else { 
+			/*
+			 * Take a reference count on the anon_vma if the
+			 * page is mapped so that it is guaranteed to
+			 * exist when the page is remapped later
+			 */
+			anon_vma = page_anon_vma(page);
+			atomic_inc(&anon_vma->external_refcount);
+		}
 	}
 
 	/*
@@ -656,9 +675,9 @@ static int unmap_and_move(new_page_t get
 
 skip_unmap:
 	if (!page_mapped(page))
-		rc = move_to_new_page(newpage, page);
+		rc = move_to_new_page(newpage, page, remap_swapcache);
 
-	if (rc)
+	if (rc && remap_swapcache)
 		remove_migration_ptes(page, page);
 rcu_unlock:
 

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[PATCH 62 of 67] do not display compaction-related stats when !CONFIG_COMPACTION

[Andrea Arcangeli]

From: Mel Gorman <mel@csn.ul.ie>

Although compaction can be disabled from .config, the vmstat entries still
exist.  This patch removes the vmstat entries.  As page_alloc.c refers
directly to the counters, the patch introduces
__alloc_pages_direct_compact() to isolate use of the counters.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -43,8 +43,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS
 		KSWAPD_LOW_WMARK_HIT_QUICKLY, KSWAPD_HIGH_WMARK_HIT_QUICKLY,
 		KSWAPD_SKIP_CONGESTION_WAIT,
 		PAGEOUTRUN, ALLOCSTALL, PGROTATED,
+#ifdef CONFIG_COMPACTION
 		COMPACTBLOCKS, COMPACTPAGES, COMPACTPAGEFAILED,
 		COMPACTSTALL, COMPACTFAIL, COMPACTSUCCESS,
+#endif
 #ifdef CONFIG_HUGETLB_PAGE
 		HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
 #endif
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1736,6 +1736,59 @@ out:
 	return page;
 }
 
+#ifdef CONFIG_COMPACTION
+/* Try memory compaction for high-order allocations before reclaim */
+static struct page *
+__alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
+	struct zonelist *zonelist, enum zone_type high_zoneidx,
+	nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone,
+	int migratetype, unsigned long *did_some_progress)
+{
+	struct page *page;
+
+	if (!order)
+		return NULL;
+
+	*did_some_progress = try_to_compact_pages(zonelist, order, gfp_mask,
+								nodemask);
+	if (*did_some_progress != COMPACT_SKIPPED) {
+
+		/* Page migration frees to the PCP lists but we want merging */
+		drain_pages(get_cpu());
+		put_cpu();
+
+		page = get_page_from_freelist(gfp_mask, nodemask,
+				order, zonelist, high_zoneidx,
+				alloc_flags, preferred_zone,
+				migratetype);
+		if (page) {
+			__count_vm_event(COMPACTSUCCESS);
+			return page;
+		}
+
+		/*
+		 * It's bad if compaction run occurs and fails.
+		 * The most likely reason is that pages exist,
+		 * but not enough to satisfy watermarks.
+		 */
+		count_vm_event(COMPACTFAIL);
+
+		cond_resched();
+	}
+
+	return NULL;
+}
+#else
+static inline struct page *
+__alloc_pages_direct_compact(gfp_t gfp_mask, unsigned int order,
+	struct zonelist *zonelist, enum zone_type high_zoneidx,
+	nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone,
+	int migratetype, unsigned long *did_some_progress)
+{
+	return NULL;
+}
+#endif /* CONFIG_COMPACTION */
+
 /* The really slow allocator path where we enter direct reclaim */
 static inline struct page *
 __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,
@@ -1957,6 +2010,15 @@ rebalance:
 	if (test_thread_flag(TIF_MEMDIE) && !(gfp_mask & __GFP_NOFAIL))
 		goto nopage;
 
+	/* Try direct compaction */
+	page = __alloc_pages_direct_compact(gfp_mask, order,
+					zonelist, high_zoneidx,
+					nodemask,
+					alloc_flags, preferred_zone,
+					migratetype, &did_some_progress);
+	if (page)
+		goto got_pg;
+
 	/* Try direct reclaim and then allocating */
 	page = __alloc_pages_direct_reclaim(gfp_mask, order,
 					zonelist, high_zoneidx,
diff --git a/mm/vmstat.c b/mm/vmstat.c
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -905,12 +905,14 @@ static const char * const vmstat_text[] 
 
 	"pgrotated",
 
+#ifdef CONFIG_COMPACTION
 	"compact_blocks_moved",
 	"compact_pages_moved",
 	"compact_pagemigrate_failed",
 	"compact_stall",
 	"compact_fail",
 	"compact_success",
+#endif
 
 #ifdef CONFIG_HUGETLB_PAGE
 	"htlb_buddy_alloc_success",

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[PATCH 63 of 67] disable migreate_prep()

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

I get trouble from lockdep if I leave it enabled:

=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.34-rc3 #50
-------------------------------------------------------
largepages/4965 is trying to acquire lock:
 (events){+.+.+.}, at: [<ffffffff8105b788>] flush_work+0x38/0x130

 but task is already holding lock:
  (&mm->mmap_sem){++++++}, at: [<ffffffff8141b022>] do_page_fault+0xd2/0x430


flush_work apparently wants to run free from lock and it bugs in:

	lock_map_acquire(&cwq->wq->lockdep_map);

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/mm/compaction.c b/mm/compaction.c
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -379,7 +379,9 @@ static int compact_zone(struct zone *zon
 	cc->free_pfn = cc->migrate_pfn + zone->spanned_pages;
 	cc->free_pfn &= ~(pageblock_nr_pages-1);
 
+#if 0
 	migrate_prep();
+#endif
 
 	while ((ret = compact_finished(zone, cc)) == COMPACT_INCOMPLETE) {
 		unsigned long nr_migrate, nr_remaining;

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[PATCH 64 of 67] page buddy can go away before reading page_order

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

zone->lock isn't hold. Let's just skip this optimization.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/mm/compaction.c b/mm/compaction.c
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -262,10 +262,8 @@ static unsigned long isolate_migratepage
 
 		/* Get the page and skip if free */
 		page = pfn_to_page(low_pfn);
-		if (PageBuddy(page)) {
-			low_pfn += (1 << page_order(page)) - 1;
+		if (PageBuddy(page))
 			continue;
-		}
 
 		/* Try isolate the page */
 		if (__isolate_lru_page(page, ISOLATE_BOTH, 0) != 0)

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[PATCH 65 of 67] select CONFIG_COMPACTION if TRANSPARENT_HUGEPAGE enabled

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

With transparent hugepage support we need compaction for the "defrag" sysfs
controls to be effective.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/mm/Kconfig b/mm/Kconfig
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -303,6 +303,7 @@ config NOMMU_INITIAL_TRIM_EXCESS
 config TRANSPARENT_HUGEPAGE
 	bool "Transparent Hugepage support" if EMBEDDED
 	depends on X86 && MMU
+	select COMPACTION
 	default y
 	help
 	  Transparent Hugepages allows the kernel to use huge pages and

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[PATCH 66 of 67] enable direct defrag

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

With memory compaction in, and lumpy-reclaim removed, it seems safe enough to
defrag memory during the (synchronous) transparent hugepage page faults
(TRANSPARENT_HUGEPAGE_DEFRAG_FLAG) and not only during khugepaged (async)
hugepage allocations that was already enabled even before memory compaction was
in (TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG).

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -28,6 +28,7 @@
  */
 unsigned long transparent_hugepage_flags __read_mostly =
 	(1<<TRANSPARENT_HUGEPAGE_FLAG)|
+	(1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)|
 	(1<<TRANSPARENT_HUGEPAGE_KHUGEPAGED_FLAG)|
 	(1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG);
 

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[PATCH 67 of 67] memcg fix prepare migration

[Andrea Arcangeli]

From: Andrea Arcangeli <aarcange@redhat.com>

If a signal is pending (task being killed by sigkill) __mem_cgroup_try_charge
will write NULL into &mem, and css_put will oops on null pointer dereference.

BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
IP: [<ffffffff810fc6cc>] mem_cgroup_prepare_migration+0x7c/0xc0
PGD a5d89067 PUD a5d8a067 PMD 0
Oops: 0000 [#1] SMP
last sysfs file: /sys/devices/platform/microcode/firmware/microcode/loading
CPU 0
Modules linked in: nfs lockd nfs_acl auth_rpcgss sunrpc acpi_cpufreq pcspkr sg [last unloaded: microcode]

Pid: 5299, comm: largepages Tainted: G        W  2.6.34-rc3 #3 Penryn1600SLI-110dB/To Be Filled By O.E.M.
RIP: 0010:[<ffffffff810fc6cc>]  [<ffffffff810fc6cc>] mem_cgroup_prepare_migration+0x7c/0xc0

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2445,12 +2445,12 @@ int mem_cgroup_prepare_migration(struct 
 	}
 	unlock_page_cgroup(pc);
 
+	*ptr = mem;
 	if (mem) {
-		ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false,
+		ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, ptr, false,
 					      PAGE_SIZE);
 		css_put(&mem->css);
 	}
-	*ptr = mem;
 	return ret;
 }
 

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Re: [PATCH 67 of 67] memcg fix prepare migration

[Daisuke Nishimura]

On Thu, 08 Apr 2010 03:51:50 +0200, Andrea Arcangeli <aarcange@redhat.com> wrote:
> From: Andrea Arcangeli <aarcange@redhat.com>
> 
> If a signal is pending (task being killed by sigkill) __mem_cgroup_try_charge
> will write NULL into &mem, and css_put will oops on null pointer dereference.
> 
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
> IP: [<ffffffff810fc6cc>] mem_cgroup_prepare_migration+0x7c/0xc0
> PGD a5d89067 PUD a5d8a067 PMD 0
> Oops: 0000 [#1] SMP
> last sysfs file: /sys/devices/platform/microcode/firmware/microcode/loading
> CPU 0
> Modules linked in: nfs lockd nfs_acl auth_rpcgss sunrpc acpi_cpufreq pcspkr sg [last unloaded: microcode]
> 
> Pid: 5299, comm: largepages Tainted: G        W  2.6.34-rc3 #3 Penryn1600SLI-110dB/To Be Filled By O.E.M.
> RIP: 0010:[<ffffffff810fc6cc>]  [<ffffffff810fc6cc>] mem_cgroup_prepare_migration+0x7c/0xc0
> 
> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Nice catch !

But I think this fix should be forwarded to 34-rc and stable. They all have
the same problem if the "current" which is doing the page migration is being
oom-killed.

Thanks,
Daisuke Nishimura.

> ---
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -2445,12 +2445,12 @@ int mem_cgroup_prepare_migration(struct 
>  	}
>  	unlock_page_cgroup(pc);
>  
> +	*ptr = mem;
>  	if (mem) {
> -		ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, &mem, false,
> +		ret = __mem_cgroup_try_charge(NULL, GFP_KERNEL, ptr, false,
>  					      PAGE_SIZE);
>  		css_put(&mem->css);
>  	}
> -	*ptr = mem;
>  	return ret;
>  }
>  

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Re: [PATCH 67 of 67] memcg fix prepare migration

[Andrew Morton]

On Thu, 8 Apr 2010 12:57:22 +0900 Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> On Thu, 08 Apr 2010 03:51:50 +0200, Andrea Arcangeli <aarcange@redhat.com> wrote:
> > From: Andrea Arcangeli <aarcange@redhat.com>
> > 
> > If a signal is pending (task being killed by sigkill) __mem_cgroup_try_charge
> > will write NULL into &mem, and css_put will oops on null pointer dereference.
> > 
> > BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
> > IP: [<ffffffff810fc6cc>] mem_cgroup_prepare_migration+0x7c/0xc0
> > PGD a5d89067 PUD a5d8a067 PMD 0
> > Oops: 0000 [#1] SMP
> > last sysfs file: /sys/devices/platform/microcode/firmware/microcode/loading
> > CPU 0
> > Modules linked in: nfs lockd nfs_acl auth_rpcgss sunrpc acpi_cpufreq pcspkr sg [last unloaded: microcode]
> > 
> > Pid: 5299, comm: largepages Tainted: G        W  2.6.34-rc3 #3 Penryn1600SLI-110dB/To Be Filled By O.E.M.
> > RIP: 0010:[<ffffffff810fc6cc>]  [<ffffffff810fc6cc>] mem_cgroup_prepare_migration+0x7c/0xc0
> > 
> > Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
> Nice catch !
> 
> But I think this fix should be forwarded to 34-rc and stable. They all have
> the same problem if the "current" which is doing the page migration is being
> oom-killed.

OK.  I added the cc:stable.  The patch gets a trivial reject vs 2.6.33,
but they'll work it out ;)

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Re: [PATCH 67 of 67] memcg fix prepare migration

[KAMEZAWA Hiroyuki]

On Thu, 08 Apr 2010 03:51:50 +0200
Andrea Arcangeli <aarcange@redhat.com> wrote:

> From: Andrea Arcangeli <aarcange@redhat.com>
> 
> If a signal is pending (task being killed by sigkill) __mem_cgroup_try_charge
> will write NULL into &mem, and css_put will oops on null pointer dereference.
> 
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
> IP: [<ffffffff810fc6cc>] mem_cgroup_prepare_migration+0x7c/0xc0
> PGD a5d89067 PUD a5d8a067 PMD 0
> Oops: 0000 [#1] SMP
> last sysfs file: /sys/devices/platform/microcode/firmware/microcode/loading
> CPU 0
> Modules linked in: nfs lockd nfs_acl auth_rpcgss sunrpc acpi_cpufreq pcspkr sg [last unloaded: microcode]
> 
> Pid: 5299, comm: largepages Tainted: G        W  2.6.34-rc3 #3 Penryn1600SLI-110dB/To Be Filled By O.E.M.
> RIP: 0010:[<ffffffff810fc6cc>]  [<ffffffff810fc6cc>] mem_cgroup_prepare_migration+0x7c/0xc0
> 
> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>

Thank you.

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>


Andrew, I think this patch itself should be queued up as bugfix to
exisiting code. It seems there is no dependecy to other pathces.

Thanks,
-Kame

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Re: [PATCH 00 of 67] Transparent Hugepage Support #18

[Avi Kivity]

On 04/08/2010 04:50 AM, Andrea Arcangeli wrote:
> Hello,
>
> I merged memory compaction v7 from Mel, plus his latest incremental updates
> into my tree.
>
>    

A quick benchmark, running 'sort -b 1200M /tmp/largerand > /dev/null'.  
The file is 1GB in size, consisting of 15-char base64 encoded random 
string + newline records.

4k:

   real    2m28.155s
   user    2m21.560s
   sys    0m6.457s

2M:

   real    2m19.626s
   user    2m13.771s
   sys    0m5.812s

A 6% improvement.

I'll try running this with a kernel build in parallel.

-- 
error compiling committee.c: too many arguments to function

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Re: [PATCH 00 of 67] Transparent Hugepage Support #18

[Avi Kivity]

On 04/08/2010 12:39 PM, Avi Kivity wrote:
> On 04/08/2010 04:50 AM, Andrea Arcangeli wrote:
>> Hello,
>>
>> I merged memory compaction v7 from Mel, plus his latest incremental 
>> updates
>> into my tree.
>>
>
> A quick benchmark, running 'sort -b 1200M /tmp/largerand > 
> /dev/null'.  The file is 1GB in size, consisting of 15-char base64 
> encoded random string + newline records.
>

That's -S, not -b.

> I'll try running this with a kernel build in parallel.

Results here are less than stellar.  While khugepaged is pulling pages 
together, something is breaking them apart.  Even after memory pressure 
is removed, this behaviour continues.  Can it be that compaction is 
tearing down huge pages?

After about 80 seconds of sort, we only have 40-50MB worth of hugepages, 
even though khugepaged is collapsing 50-100 per second (which should 
have got the job done in 5-10 seconds).

After dropping pagecache, we get about 800MB of large pages, so it looks 
like antifrag/compaction isn't able to deal with pagecache well.  
Dropping dcache adds a further 100MB.

All this with mem=2G.

-- 
error compiling committee.c: too many arguments to function

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Re: [PATCH 00 of 67] Transparent Hugepage Support #18

[Andrea Arcangeli]

On Thu, Apr 08, 2010 at 02:44:01PM +0300, Avi Kivity wrote:
> Results here are less than stellar.  While khugepaged is pulling pages 
> together, something is breaking them apart.  Even after memory pressure 
> is removed, this behaviour continues.  Can it be that compaction is 
> tearing down huge pages?

migrate will split hugepages, but memory compaction shouldn't migrate
hugepages... If it does I agree it needs fixing.

At the moment the main problem I'm having is that only way to run
stable for me is to stop at patch 48 (included). So it's something
wrong with memory compaction or migrate.

It crashes in migration_entry_to_page() here:

   BUG_ON(!PageLocked(p));

because p == ffffea06ac000000 and segfaults in reading p->flags inside
Pagelocked.

I recommend to run my git tree (aa.git) on your systems to exercise
migration and memory compaction to the maximum extent in the hope to
reproduce the below. Without transparent hugepage support there is no
chance to ever reproduce bugs in memory compaction.

If you want to be 100% safe and still use transparent hugepage just
stop at patch 48 (included) or checkout commit
e9f16129c80468cfd551ffc9cf92c9c46304195a instead of origin/master.
Hopefully memory compaction or migration will be fixed soon enough.

Thanks,
Andrea

Apr  8 08:02:57 v2 kernel: BUG: unable to handle kernel paging request at ffffea06ac000000
Apr  8 08:02:57 v2 kernel: IP: [<ffffffff810dc73d>] remove_migration_pte+0x19d/0x240
Apr  8 08:02:57 v2 kernel: PGD 20c9067 PUD 0 
Apr  8 08:02:57 v2 kernel: Oops: 0000 [#1] SMP 
Apr  8 08:02:57 v2 kernel: last sysfs file: /sys/devices/pci0000:00/0000:00:12.0/host1/uevent
Apr  8 08:02:57 v2 kernel: CPU 1 
Apr  8 08:02:57 v2 kernel: Modules linked in: twofish twofish_common tun bridge stp llc bnep sco rfcomm l2cap bluetooth snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss usbhid gspca_pac207 gspca_main videodev v4l1_compat v4l2_compat_ioctl32 ohci_hcd snd_hda_codec_realtek ehci_hcd usbcore sr_mod pcspkr sg psmouse snd_hda_intel snd_hda_codec snd_pcm snd_timer snd snd_page_alloc
Apr  8 08:02:57 v2 kernel: 
Apr  8 08:02:57 v2 kernel: Pid: 18001, comm: python2.6 Not tainted 2.6.34-rc3 #6 M2A-VM/System Product Name
Apr  8 08:02:57 v2 kernel: RIP: 0010:[<ffffffff810dc73d>]  [<ffffffff810dc73d>] remove_migration_pte+0x19d/0x240
Apr  8 08:02:57 v2 kernel: RSP: 0000:ffff8800c55a79a8  EFLAGS: 00010206
Apr  8 08:02:57 v2 kernel: RAX: 000000000000001f RBX: ffffea0002487ba0 RCX: ffffea0000372658
Apr  8 08:02:57 v2 kernel: RDX: 000000000541d000 RSI: ffff8800d1ed4528 RDI: ffffea06ac000000
Apr  8 08:02:57 v2 kernel: RBP: ffffea0000532000 R08: 00000006ac000000 R09: 0000000000000000
Apr  8 08:02:57 v2 kernel: R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
Apr  8 08:02:57 v2 kernel: R13: ffff880017c000e8 R14: ffff88011ee5e470 R15: ffff88011ee5e468
Apr  8 08:02:57 v2 kernel: FS:  00007fc8f93136f0(0000) GS:ffff880001a80000(0000) knlGS:0000000055702bd0
Apr  8 08:02:57 v2 kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Apr  8 08:02:57 v2 kernel: CR2: ffffea06ac000000 CR3: 000000000977a000 CR4: 00000000000006e0
Apr  8 08:02:57 v2 kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Apr  8 08:02:57 v2 kernel: DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Apr  8 08:02:57 v2 kernel: Process python2.6 (pid: 18001, threadinfo ffff8800c55a6000, task ffff8800096e32d0)
Apr  8 08:02:57 v2 kernel: Stack:
Apr  8 08:02:57 v2 kernel: ffff88011ddeb380 ffffea0000372658 000000000541d000 ffff8800d1ed4528
Apr  8 08:02:57 v2 kernel: <0> ffff8800d58f8d08 ffff8800d58d2f18 ffffea0002487ba0 ffffffff810dc5a0
Apr  8 08:02:57 v2 kernel: <0> ffffea0000372658 ffffffff810ca155 ffffffff81797580 ffff88011dd77618
Apr  8 08:02:57 v2 kernel: Call Trace:
Apr  8 08:02:57 v2 kernel: [<ffffffff810dc5a0>] ? remove_migration_pte+0x0/0x240
Apr  8 08:02:57 v2 kernel: [<ffffffff810ca155>] ? rmap_walk+0x135/0x180
Apr  8 08:02:57 v2 kernel: [<ffffffff810dcbe9>] ? migrate_page_copy+0xe9/0x190
Apr  8 08:02:57 v2 kernel: [<ffffffff810dd141>] ? migrate_pages+0x471/0x660
Apr  8 08:02:57 v2 kernel: [<ffffffff810dda40>] ? compaction_alloc+0x0/0x360
Apr  8 08:02:57 v2 kernel: [<ffffffff8100368e>] ? apic_timer_interrupt+0xe/0x20
Apr  8 08:02:57 v2 kernel: [<ffffffff810dd876>] ? compact_zone+0x406/0x500
Apr  8 08:02:57 v2 kernel: [<ffffffff810dde1b>] ? compact_zone_order+0x7b/0xb0
Apr  8 08:02:57 v2 kernel: [<ffffffff810ddf4d>] ? try_to_compact_pages+0xfd/0x170
Apr  8 08:02:57 v2 kernel: [<ffffffff810acc12>] ? __alloc_pages_nodemask+0x512/0x850
Apr  8 08:02:57 v2 kernel: [<ffffffff810e2808>] ? do_huge_pmd_wp_page+0x4b8/0x6e0
Apr  8 08:02:57 v2 kernel: [<ffffffff810c14a2>] ? handle_mm_fault+0x132/0x350
Apr  8 08:02:57 v2 kernel: [<ffffffff814f81ed>] ? do_page_fault+0x13d/0x420
Apr  8 08:02:57 v2 kernel: [<ffffffff814f52df>] ? page_fault+0x1f/0x30
Apr  8 08:02:57 v2 kernel: [<ffffffff812692dd>] ? __put_user_4+0x1d/0x30
Apr  8 08:02:57 v2 kernel: [<ffffffff814f52df>] ? page_fault+0x1f/0x30
Apr  8 08:02:57 v2 kernel: Code: 24 38 4c 8b 6c 24 40 48 83 c4 48 c3 49 b8 ff ff ff ff ff ff ff 07 4c 21 c7 4c 6b c7 38 48 bf 00 00 00 00 00 ea ff ff 49 8d 3c 38 <f6> 07 01 0f 84 8c 00 00 00 48 39 f9 75 ac f0 ff 43 08 66 83 3b 
Apr  8 08:02:57 v2 kernel: RIP  [<ffffffff810dc73d>] remove_migration_pte+0x19d/0x240
Apr  8 08:02:57 v2 kernel: RSP <ffff8800c55a79a8>
Apr  8 08:02:57 v2 kernel: CR2: ffffea06ac000000
Apr  8 08:02:57 v2 kernel: ---[ end trace 9bc19f8bd2737926 ]---

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Re: [PATCH 00 of 67] Transparent Hugepage Support #18

[Avi Kivity]

On 04/08/2010 06:23 PM, Andrea Arcangeli wrote:
> On Thu, Apr 08, 2010 at 02:44:01PM +0300, Avi Kivity wrote:
>    
>> Results here are less than stellar.  While khugepaged is pulling pages
>> together, something is breaking them apart.  Even after memory pressure
>> is removed, this behaviour continues.  Can it be that compaction is
>> tearing down huge pages?
>>      
> migrate will split hugepages, but memory compaction shouldn't migrate
> hugepages... If it does I agree it needs fixing.
>
>    

Well, khugepaged was certainly fighting with something.  Perhaps ftrace 
will point the finger.

> At the moment the main problem I'm having is that only way to run
> stable for me is to stop at patch 48 (included). So it's something
> wrong with memory compaction or migrate.
>    

It ran stably for me FWIW.

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Re: [PATCH 00 of 67] Transparent Hugepage Support #18

[Andrea Arcangeli]

On Thu, Apr 08, 2010 at 06:27:06PM +0300, Avi Kivity wrote:
> On 04/08/2010 06:23 PM, Andrea Arcangeli wrote:
> > On Thu, Apr 08, 2010 at 02:44:01PM +0300, Avi Kivity wrote:
> >    
> >> Results here are less than stellar.  While khugepaged is pulling pages
> >> together, something is breaking them apart.  Even after memory pressure
> >> is removed, this behaviour continues.  Can it be that compaction is
> >> tearing down huge pages?
> >>      
> > migrate will split hugepages, but memory compaction shouldn't migrate
> > hugepages... If it does I agree it needs fixing.
> >
> >    
> 
> Well, khugepaged was certainly fighting with something.  Perhaps ftrace 
> will point the finger.

It's likely splitting and migrating hugepages really, like you just
said.

> It ran stably for me FWIW.

It's not easily reproducible (the tiny race in memcg prepare_migration
also was hard to reproduce but that one was easy to fix by reproducing
it just once). I suspect something's wrong with isolate_migratepages,
I don't see where it skips tail pages, and it should skip all compound
pages to avoid migrating them which would also solve your
issue. something like that... ;). I think migration splits the
hugepages good enough and while migration has a pin on the page (to
keep khugepaged away).

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Re: [PATCH 00 of 67] Transparent Hugepage Support #18

[Christoph Lameter]

On Thu, 8 Apr 2010, Andrea Arcangeli wrote:

> Hopefully memory compaction or migration will be fixed soon enough.

Here are my earlier comments on this issue:


On Thu, 8 Apr 2010, Andrea Arcangeli wrote:

> Since I merged memory compaction things become very unstable.
>
> This is one debug info I collected. It crashes in
> migration_entry_to_page() here:
>
> BUG_ON(!PageLocked(p));
>
> because p == ffffea06ac000000 and segfaults in reading p->flags inside
> Pagelocked.

This means that migration_entry_to_page was passed an invalid pointer.
Note that remove_migration_ptes walks the page table. There is no current
code that deals with 2M pages in the walker.

> Please help to fix this, this is by far the highest priority at the
> moment and it has nothing to do with transparent hugepages, it's
> either a memory compaction or migration proper bug.

If the page table contains proper values then this should not occur unless
there is a now a 2M special case added.

The entry that is passed to migration_entry_to_page() is obtained from the
page table pte via pte_to_swp_entry().

> Apr  8 08:02:57 v2 kernel: [<ffffffff810dc5a0>] ? remove_migration_pte+0x0/0x240
> Apr  8 08:02:57 v2 kernel: [<ffffffff810ca155>] ? rmap_walk+0x135/0x180
> Apr  8 08:02:57 v2 kernel: [<ffffffff810dcbe9>] ? migrate_page_copy+0xe9/0x190

Stack dump messed up? migrate_page_copy should not call any pte functions.

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Re: [PATCH 00 of 67] Transparent Hugepage Support #18

[Andrea Arcangeli]

This may have been caused by the same anon-vma bug that is being
debugged for mainline as it'd free anon-vma too early leading to
memory corruption. split_huge_page is a super heavy user of anon-vmas,
so that would explain all the issues, and also another crash I had in
split_huge_page where the rmap chain found a number of pmd mapping the
hugepage different than page_mapcount. For swap that means mlock, for
split_huge_page not being able to update some huge pmd is fatal so
there's plenty of BUG_ON to check all goes well and there's no risk of
corruption later on.

We need to test with Linus's fix for anon-vma bug, and I guess
everything will go fine when that bug is solved.

I added more commentary as well to cover an ordering issue in the
anon_vma_prepare.

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Re: [PATCH 00 of 67] Transparent Hugepage Support #18

[Avi Kivity]

On 04/08/2010 02:44 PM, Avi Kivity wrote:
>
>> I'll try running this with a kernel build in parallel.
>
> Results here are less than stellar.  While khugepaged is pulling pages 
> together, something is breaking them apart.  Even after memory 
> pressure is removed, this behaviour continues.  Can it be that 
> compaction is tearing down huge pages?

ok, #19 is a different story.  A 1.2GB sort vs 'make -j12' and a cat of 
the source tree and some light swapping, all in 2GB RAM, didn't quite 
reach 1.2GB but came fairly close.  The sort was started while memory 
was quite low so it had to fight its way up, but even then khugepaged 
took less that 1.5 seconds total time after a _very_ long compile.

I observed huge pages being used for gcc as well, likely not bringing 
much performance since kernel compiles don't use a lot of memory per 
file.  I'll look at the link stage, that will probably use a lot of 
large pages.

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Re: [PATCH 00 of 67] Transparent Hugepage Support #18

[Andrea Arcangeli]

On Fri, Apr 09, 2010 at 11:45:20AM +0300, Avi Kivity wrote:
> On 04/08/2010 02:44 PM, Avi Kivity wrote:
> >
> >> I'll try running this with a kernel build in parallel.
> >
> > Results here are less than stellar.  While khugepaged is pulling pages 
> > together, something is breaking them apart.  Even after memory 
> > pressure is removed, this behaviour continues.  Can it be that 
> > compaction is tearing down huge pages?
> 
> ok, #19 is a different story.  A 1.2GB sort vs 'make -j12' and a cat of 
> the source tree and some light swapping, all in 2GB RAM, didn't quite 
> reach 1.2GB but came fairly close.  The sort was started while memory 
> was quite low so it had to fight its way up, but even then khugepaged 
> took less that 1.5 seconds total time after a _very_ long compile.

Good. Also please check you're on
8707120d97e7052ffb45f9879efce8e7bd361711, with that one all bugs are
ironed out, it's stable on all my systems under constant mixed heavy
load (the same load would crash it in 1 hour with the memory
compaction bug, or half a day with the anon-vma bugs and no memory
compaction). 8707120d97e7052ffb45f9879efce8e7bd361711 is rock solid as
far as I can tell.

> I observed huge pages being used for gcc as well, likely not bringing 
> much performance since kernel compiles don't use a lot of memory per 
> file.  I'll look at the link stage, that will probably use a lot of 
> large pages.

I also observed them but not too many.... not the whole >200M. You
should probably decrease scan_sleep_millisecs (and
alloc_sleep_millisecs). If you set scan_sleep_millisecs to 0, you'll
run khugepaged in a loop, so gcc should get a whole lot of
hugepages. Only problem is the cost of the khugepaged pmd scan
itself... gcc is too short, but for all longstanding apps khugepaged
is already capable of dealing with slowly extending vm_end even when
run with default scan millisecs.

I guess I'll look into glibc to see what we can do to have gcc use
100% hugepages and hopefully run 6% faster too.

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Re: [PATCH 00 of 67] Transparent Hugepage Support #18

[Avi Kivity]

On 04/09/2010 06:50 PM, Andrea Arcangeli wrote:
>
>> ok, #19 is a different story.  A 1.2GB sort vs 'make -j12' and a cat of
>> the source tree and some light swapping, all in 2GB RAM, didn't quite
>> reach 1.2GB but came fairly close.  The sort was started while memory
>> was quite low so it had to fight its way up, but even then khugepaged
>> took less that 1.5 seconds total time after a _very_ long compile.
>>      
> Good. Also please check you're on
> 8707120d97e7052ffb45f9879efce8e7bd361711, with that one all bugs are
> ironed out, it's stable on all my systems under constant mixed heavy
> load (the same load would crash it in 1 hour with the memory
> compaction bug, or half a day with the anon-vma bugs and no memory
> compaction). 8707120d97e7052ffb45f9879efce8e7bd361711 is rock solid as
> far as I can tell.
>    

Yes, that's what I used.

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Transparent Hugepage Support #19

[Andrea Arcangeli]

Hello,

I'm not patchbombing further due the size of the patchset (71 patches
now).

git clone git://git.kernel.org/pub/scm/linux/kernel/git/andrea/aa.git
git clone --reference linux-2.6 git://git.kernel.org/pub/scm/linux/kernel/git/andrea/aa.git

http://www.kernel.org/pub/linux/kernel/people/andrea/patches/v2.6/2.6.34-rc3/transparent_hugepage-19/
http://www.kernel.org/pub/linux/kernel/people/andrea/patches/v2.6/2.6.34-rc3/transparent_hugepage-19.gz

Differences from #18:

1) backout mainline anon-vma changes, I had one bugcheck trigger that
   seems could be caused by bugs in the anon-vma changes. Those bugs
   are much more noticeable and severe with transparent hugepage
   support enabled. I tried the patches available but named wouldn't
   start anymore with futex returning sigbus. Note the commentary
   added here about it:

   http://www.kernel.org/pub/linux/kernel/people/andrea/patches/v2.6/2.6.34-rc3/transparent_hugepage-19/split_huge_page-anon_vma

2) don't compact already compcat transparent hugepages (thanks to Avi,
   Mel and Johannes for the help). Avi you may want to re-test the
   sort workload with kernel build in parallel, memory compaction
   won't split hugepages anymore.

   http://www.kernel.org/pub/linux/kernel/people/andrea/patches/v2.6/2.6.34-rc3/transparent_hugepage-19/transhuge-isolate_migratepages

3) include AnonHugePages into AnonPages in /proc/meminfo as suggested
   by Avi

   http://www.kernel.org/pub/linux/kernel/people/andrea/patches/v2.6/2.6.34-rc3/transparent_hugepage-19/transparent_hugepage_vmstat

4) fix some issue in move_pages syscall (using a suggestion from
   Christoph to have follow_page split them internally, adding
   FOLL_SPLIT). Otherwise only the second run of move_pages would
   succeed. This is one of the special user of gup that like futex is
   doing more than just DMA or obtaining physical address of the page
   to setup a secondary MMU on the virtual memory.

   http://www.kernel.org/pub/linux/kernel/people/andrea/patches/v2.6/2.6.34-rc3/transparent_hugepage-19/pmd_trans_huge_migrate

Let's see if this makes it rock solid..... I loaded it in enough
places that we'll know in a couple of days. I recommend to use this
tree for the benchmarking.

Thanks,
Andrea

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Re: Transparent Hugepage Support #19

[Andrea Arcangeli]

Ok the below bug (that triggered without memory compaction) gone away
in #19 after backing out the anon-vma changes.

Apr  8 10:10:30 duo kernel: ------------[ cut here ]------------
Apr  8 10:10:30 duo kernel: kernel BUG at mm/huge_memory.c:1284!
Apr  8 10:10:30 duo kernel: invalid opcode: 0000 [#1] SMP 
Apr  8 10:10:30 duo kernel: last sysfs file: /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0A:00/power_supply/BAT0/charge_full
Apr  8 10:10:30 duo kernel: CPU 1 
Apr  8 10:10:30 duo kernel: Modules linked in: tun coretemp bridge stp llc bnep sco rfcomm l2cap snd_seq_dummy snd_seq_oss snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss btusb bluetooth usbhid acpi_cpufreq uvcvideo videodev v4l1_compat v4l2_compat_ioctl32 arc4 ecb snd_hda_codec_intelhdmi iwlagn snd_hda_codec_idt uhci_hcd iwlcore mac80211 ehci_hcd snd_hda_intel usbcore snd_hda_codec snd_pcm snd_timer cfg80211 sdhci_pci sdhci rfkill snd tg3 mmc_core sg pcspkr soundcore snd_page_alloc psmouse libphy led_class i2c_i801 [last unloaded: microcode]
Apr  8 10:10:30 duo kernel: 
Apr  8 10:10:30 duo kernel: Pid: 8604, comm: javac Not tainted 2.6.34-rc3 #15 0N6705/XPS M1330                       
Apr  8 10:10:30 duo kernel: RIP: 0010:[<ffffffff810e5bc3>]  [<ffffffff810e5bc3>] split_huge_page+0x593/0x5e0
Apr  8 10:10:30 duo kernel: RSP: 0018:ffff8800bdc71d98  EFLAGS: 00010297
Apr  8 10:10:30 duo kernel: RAX: 0000000000000001 RBX: ffffea00003fe000 RCX: 0000000000000002
Apr  8 10:10:30 duo kernel: RDX: 0000000000000000 RSI: ffff8800a93e0870 RDI: ffffea00003fe000
Apr  8 10:10:30 duo kernel: RBP: ffff8800ade2ca98 R08: 0000000000000000 R09: 0000000000000000
Apr  8 10:10:30 duo kernel: R10: 00003ffffffff278 R11: 00007f8ca71fdfff R12: fffffffffffffff2
Apr  8 10:10:30 duo kernel: R13: ffff8800a93e0870 R14: 0000000000000120 R15: ffff8800ade2cab8
Apr  8 10:10:30 duo kernel: FS:  00007f8ca72fb910(0000) GS:ffff880001b00000(0000) knlGS:0000000000000000
Apr  8 10:10:30 duo kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
Apr  8 10:10:30 duo kernel: CR2: 00007f8ca71fada8 CR3: 0000000084546000 CR4: 00000000000006e0
Apr  8 10:10:30 duo kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
Apr  8 10:10:30 duo kernel: DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Apr  8 10:10:30 duo kernel: Process javac (pid: 8604, threadinfo ffff8800bdc70000, task ffff880051ead910)
Apr  8 10:10:30 duo kernel: Stack:
Apr  8 10:10:30 duo kernel: 00000000bc638180 0000000000000000 00007f8ca71fe000 0000000000000000
Apr  8 10:10:30 duo kernel: <0> 00007f8ca71fb000 00000007f8ca71fb 0000000000004000 ffff8800ade2cab8
Apr  8 10:10:30 duo kernel: <0> ffff8800a0bb7720 ffff8800ade2cab0 ffff8800bc638180 ffffea00003fe000
Apr  8 10:10:30 duo kernel: Call Trace:
Apr  8 10:10:30 duo kernel: [<ffffffff810e5c81>] ? __split_huge_page_pmd+0x71/0xc0
Apr  8 10:10:30 duo kernel: [<ffffffff810cc0d2>] ? mprotect_fixup+0x332/0x740
Apr  8 10:10:30 duo kernel: [<ffffffff810cc635>] ? sys_mprotect+0x155/0x240
Apr  8 10:10:30 duo kernel: [<ffffffff81002e2b>] ? system_call_fastpath+0x16/0x1b
Apr  8 10:10:30 duo kernel: Code: eb fe 48 89 44 24 20 4c 89 e6 e8 09 5b ff ff 48 8b 44 24 20 e9 79 fb ff ff 48 8b 54 24 28 4c 89 e6 e8 92 5a ff ff e9 87 fb ff ff <0f> 0b eb fe 48 8b 03 a9 00 00 00 01 90 0f 84 da fb ff ff f3 90 
Apr  8 10:10:30 duo kernel: RIP  [<ffffffff810e5bc3>] split_huge_page+0x593/0x5e0
Apr  8 10:10:30 duo kernel: RSP <ffff8800bdc71d98>
Apr  8 10:10:30 duo kernel: ---[ end trace fe3fb34de5cea3c2 ]---

The other bug in remove_migration_pte I reproduced in #19 too and this
time I tracked it down and fixed it.

diff --git a/mm/migrate.c b/mm/migrate.c
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -100,6 +100,13 @@ static int remove_migration_pte(struct p
 		goto out;
 
 	pmd = pmd_offset(pud, addr);
+	if (pmd_trans_huge(*pmd)) {
+		/* verify this pmd isn't mapping our old page */
+		BUG_ON(!pmd_present(*pmd));
+		BUG_ON(PageTransCompound(old));
+		BUG_ON(pmd_page(*pmd) == old);
+		goto out;
+	}
 	if (!pmd_present(*pmd))
 		goto out;
 

The hotfix is already applied in aa.git origin/master branch. So with
current aa.git 8707120d97e7052ffb45f9879efce8e7bd361711 we're totally
stable again even with memory compaction enabled by default in direct
reclaim of transparent hugepage page faults. Enjoy! ;). As usual with
rebased branches you can just "git fetch; git checkout -f origin/master".

Now that all stability issues are sorted out I'll add numa awareness
to alloc_hugepage, something I deferred doing until we were stable
(again). Then I'll release #20.

Thanks,
Andrea

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