[PATCH 0/11] update page table walker

[PATCH 0/11] update page table walker

[Naoya Horiguchi]

Page table walker is widely used when you want to traverse page table
tree and do some work for the entries (and pages pointed to by them.)
This is a common operation, and keep the code clean and maintainable
is important. Moreover this patchset introduces caller-specific walk
control function which is helpful for us to newly introduce page table
walker to some other users. Core change comes from patch 1, so please
see it for how it's supposed to work.

This patchset changes core code in mm/pagewalk.c at first in patch 1 and 2,
and then updates all of current users to make the code cleaner in patch
3-9. Patch 10 changes the interface of hugetlb_entry(), I put it here to
keep bisectability of the whole patchset. Patch 11 applies page table walker
to a new user queue_pages_range().

There're some other candidates of new users of page table walker:
 - do_mincore()
 - copy_page_range()
 - remap_pfn_range()
 - zap_page_range()
 - free_pgtables()
 - vmap_page_range_noflush()
 - change_protection_range()
, but at the first step I start with adding only one new user,
queue_pages_range().

Any comments?

Thanks,
Naoya Horiguchi
---
GitHub:
  git://github.com/Naoya-Horiguchi/linux.git v3.12-rc4/rewrite_pagewalker.v1

Test code:
  git://github.com/Naoya-Horiguchi/test_rewrite_page_table_walker.git
---
Summary:

Naoya Horiguchi (11):
      pagewalk: update page table walker core
      pagewalk: add walk_page_vma()
      smaps: redefine callback functions for page table walker
      clear_refs: redefine callback functions for page table walker
      pagemap: redefine callback functions for page table walker
      numa_maps: redefine callback functions for page table walker
      memcg: redefine callback functions for page table walker
      madvise: redefine callback functions for page table walker
      arch/powerpc/mm/subpage-prot.c: use walk_page_vma() instead of walk_page_range()
      pagewalk: remove argument hmask from hugetlb_entry()
      mempolicy: apply page table walker on queue_pages_range()

 arch/powerpc/mm/subpage-prot.c |   6 +-
 fs/proc/task_mmu.c             | 262 +++++++++++++-----------------
 include/linux/mm.h             |  24 ++-
 mm/madvise.c                   |  43 ++---
 mm/memcontrol.c                |  72 ++++-----
 mm/mempolicy.c                 | 251 +++++++++++------------------
 mm/pagewalk.c                  | 352 +++++++++++++++++++++++++----------------
 7 files changed, 482 insertions(+), 528 deletions(-)

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 01/11] pagewalk: update page table walker core

[Naoya Horiguchi]

This patch updates mm/pagewalk.c to make code less complex and more maintenable.
The basic idea is unchanged and there's no userspace visible effect.

Most of existing callback functions need access to vma to handle each entry.
So we had better add a new member vma in struct mm_walk instead of using
mm_walk->private, which makes code simpler.

One problem in current page table walker is that we check vma in pgd loop.
Historically this was introduced to support hugetlbfs in the strange manner.
It's better and cleaner to do the vma check outside pgd loop.

Another problem is that many users of page table walker now use only
pmd_entry(), although it does both pmd-walk and pte-walk. This makes code
duplication and fluctuation among callers, which worsens the maintenability.

One difficulty of code sharing is that the callers want to determine
whether they try to walk over a specific vma or not in their own way.
To realize that this patch introduces test_walk() callback.

When we try to use multiple callbacks in different levels, skip control is
also important. For example we have thp enabled in normal configuration, and
we are interested in doing some work for a thp. But sometimes we want to
split it and handle as normal pages, and in another time user would handle
both at pmd level and pte level.
What we need is that when we've done pmd_entry() we want to decide whether
to go down to pte level handling based on the pmd_entry()'s result. So this
patch introduces a skip control flag in mm_walk.
We can't use the returned value for this purpose, because we already
defined the meaning of whole range of returned values (>0 is caller
defined termination of page table walk, =0 is to continue to walk,
and <0 is to abort the walk.)

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 include/linux/mm.h |  18 ++-
 mm/pagewalk.c      | 330 ++++++++++++++++++++++++++++++++---------------------
 2 files changed, 214 insertions(+), 134 deletions(-)

diff --git v3.12-rc4.orig/include/linux/mm.h v3.12-rc4/include/linux/mm.h
index 8b6e55e..bd87065 100644
--- v3.12-rc4.orig/include/linux/mm.h
+++ v3.12-rc4/include/linux/mm.h
@@ -942,10 +942,18 @@ void unmap_vmas(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
  * @pte_entry: if set, called for each non-empty PTE (4th-level) entry
  * @pte_hole: if set, called for each hole at all levels
  * @hugetlb_entry: if set, called for each hugetlb entry
- *		   *Caution*: The caller must hold mmap_sem() if @hugetlb_entry
- * 			      is used.
+ * @test_walk: caller specific callback function to determine whether
+ *             we walk over the current vma or not. A positive returned
+ *             value means "do page table walk over the current vma,"
+ *             and a negative one means "abort current page table walk
+ *             right now." 0 means "skip the current vma."
+ * @mm:        mm_struct representing the target process of page table walk
+ * @vma:       vma currently walked
+ * @skip:      internal control flag which is set when we skip the lower
+ *             level entries.
+ * @private:   private data for callbacks' use
  *
- * (see walk_page_range for more details)
+ * (see the comment on walk_page_range() for more details)
  */
 struct mm_walk {
 	int (*pgd_entry)(pgd_t *pgd, unsigned long addr,
@@ -961,7 +969,11 @@ struct mm_walk {
 	int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
 			     unsigned long addr, unsigned long next,
 			     struct mm_walk *walk);
+	int (*test_walk)(unsigned long addr, unsigned long next,
+			struct mm_walk *walk);
 	struct mm_struct *mm;
+	struct vm_area_struct *vma;
+	int skip;
 	void *private;
 };
 
diff --git v3.12-rc4.orig/mm/pagewalk.c v3.12-rc4/mm/pagewalk.c
index 5da2cbc..9e95541 100644
--- v3.12-rc4.orig/mm/pagewalk.c
+++ v3.12-rc4/mm/pagewalk.c
@@ -3,29 +3,32 @@
 #include <linux/sched.h>
 #include <linux/hugetlb.h>
 
-static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
-			  struct mm_walk *walk)
+static int walk_pte_range(pmd_t *pmd, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
 {
+	struct mm_struct *mm = walk->mm;
 	pte_t *pte;
+	pte_t *orig_pte;
+	spinlock_t *ptl;
 	int err = 0;
 
-	pte = pte_offset_map(pmd, addr);
-	for (;;) {
+	orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+	do {
+		/*
+		 * Callers should have their own way to handle swap entries
+		 * in walk->pte_entry().
+		 */
 		err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
 		if (err)
 		       break;
-		addr += PAGE_SIZE;
-		if (addr == end)
-			break;
-		pte++;
-	}
-
-	pte_unmap(pte);
-	return err;
+	} while (pte++, addr += PAGE_SIZE, addr < end);
+	pte_unmap_unlock(orig_pte, ptl);
+	cond_resched();
+	return addr == end ? 0 : err;
 }
 
-static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
-			  struct mm_walk *walk)
+static int walk_pmd_range(pud_t *pud, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
 {
 	pmd_t *pmd;
 	unsigned long next;
@@ -35,6 +38,7 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 	do {
 again:
 		next = pmd_addr_end(addr, end);
+
 		if (pmd_none(*pmd)) {
 			if (walk->pte_hole)
 				err = walk->pte_hole(addr, next, walk);
@@ -42,35 +46,34 @@ static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
 				break;
 			continue;
 		}
-		/*
-		 * This implies that each ->pmd_entry() handler
-		 * needs to know about pmd_trans_huge() pmds
-		 */
-		if (walk->pmd_entry)
-			err = walk->pmd_entry(pmd, addr, next, walk);
-		if (err)
-			break;
 
-		/*
-		 * Check this here so we only break down trans_huge
-		 * pages when we _need_ to
-		 */
-		if (!walk->pte_entry)
-			continue;
+		if (walk->pmd_entry) {
+			err = walk->pmd_entry(pmd, addr, next, walk);
+			if (walk->skip) {
+				walk->skip = 0;
+				continue;
+			}
+			if (err)
+				break;
+		}
 
-		split_huge_page_pmd_mm(walk->mm, addr, pmd);
-		if (pmd_none_or_trans_huge_or_clear_bad(pmd))
-			goto again;
-		err = walk_pte_range(pmd, addr, next, walk);
-		if (err)
-			break;
+		if (walk->pte_entry) {
+			if (walk->vma) {
+				split_huge_page_pmd(walk->vma, addr, pmd);
+				if (pmd_trans_unstable(pmd))
+					goto again;
+			}
+			err = walk_pte_range(pmd, addr, next, walk);
+			if (err)
+				break;
+		}
 	} while (pmd++, addr = next, addr != end);
 
 	return err;
 }
 
-static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
-			  struct mm_walk *walk)
+static int walk_pud_range(pgd_t *pgd, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
 {
 	pud_t *pud;
 	unsigned long next;
@@ -79,6 +82,7 @@ static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
 	pud = pud_offset(pgd, addr);
 	do {
 		next = pud_addr_end(addr, end);
+
 		if (pud_none_or_clear_bad(pud)) {
 			if (walk->pte_hole)
 				err = walk->pte_hole(addr, next, walk);
@@ -86,17 +90,66 @@ static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
 				break;
 			continue;
 		}
-		if (walk->pud_entry)
+
+		if (walk->pud_entry) {
 			err = walk->pud_entry(pud, addr, next, walk);
-		if (!err && (walk->pmd_entry || walk->pte_entry))
+			if (walk->skip) {
+				walk->skip = 0;
+				continue;
+			}
+			if (err)
+				break;
+		}
+
+		if (walk->pmd_entry || walk->pte_entry) {
 			err = walk_pmd_range(pud, addr, next, walk);
-		if (err)
-			break;
+			if (err)
+				break;
+		}
 	} while (pud++, addr = next, addr != end);
 
 	return err;
 }
 
+static int walk_pgd_range(unsigned long addr, unsigned long end,
+			struct mm_walk *walk)
+{
+	pgd_t *pgd;
+	unsigned long next;
+	int err = 0;
+
+	pgd = pgd_offset(walk->mm, addr);
+	do {
+		next = pgd_addr_end(addr, end);
+
+		if (pgd_none_or_clear_bad(pgd)) {
+			if (walk->pte_hole)
+				err = walk->pte_hole(addr, next, walk);
+			if (err)
+				break;
+			continue;
+		}
+
+		if (walk->pgd_entry) {
+			err = walk->pgd_entry(pgd, addr, next, walk);
+			if (walk->skip) {
+				walk->skip = 0;
+				continue;
+			}
+			if (err)
+				break;
+		}
+
+		if (walk->pud_entry || walk->pmd_entry || walk->pte_entry) {
+			err = walk_pud_range(pgd, addr, next, walk);
+			if (err)
+				break;
+		}
+	} while (pgd++, addr = next, addr != end);
+
+	return err;
+}
+
 #ifdef CONFIG_HUGETLB_PAGE
 static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
 				       unsigned long end)
@@ -105,144 +158,159 @@ static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
 	return boundary < end ? boundary : end;
 }
 
-static int walk_hugetlb_range(struct vm_area_struct *vma,
-			      unsigned long addr, unsigned long end,
-			      struct mm_walk *walk)
+static int walk_hugetlb_range(unsigned long addr, unsigned long end,
+				struct mm_walk *walk)
 {
-	struct hstate *h = hstate_vma(vma);
+	struct mm_struct *mm = walk->mm;
+	struct vm_area_struct *vma = walk->vma;
+	struct hstate *h;
 	unsigned long next;
-	unsigned long hmask = huge_page_mask(h);
+	unsigned long hmask;
 	pte_t *pte;
 	int err = 0;
 
+	VM_BUG_ON(!vma);
+	h = hstate_vma(vma);
+	hmask = huge_page_mask(h);
+
+	spin_lock(&mm->page_table_lock);
 	do {
 		next = hugetlb_entry_end(h, addr, end);
 		pte = huge_pte_offset(walk->mm, addr & hmask);
+		/*
+		 * Callers should have their own way to handle swap entries
+		 * in walk->hugetlb_entry().
+		 */
 		if (pte && walk->hugetlb_entry)
 			err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
 		if (err)
-			return err;
+			break;
 	} while (addr = next, addr != end);
-
-	return 0;
+	spin_unlock(&mm->page_table_lock);
+	return err;
 }
 
 #else /* CONFIG_HUGETLB_PAGE */
-static int walk_hugetlb_range(struct vm_area_struct *vma,
-			      unsigned long addr, unsigned long end,
-			      struct mm_walk *walk)
+static inline int walk_hugetlb_range(unsigned long addr, unsigned long end,
+				struct mm_walk *walk)
 {
 	return 0;
 }
 
 #endif /* CONFIG_HUGETLB_PAGE */
 
+static int walk_page_test(unsigned long start, unsigned long end,
+			struct mm_walk *walk)
+{
+	int err = 0;
+	struct vm_area_struct *vma = walk->vma;
 
+	/*
+	 * Do not walk over vma(VM_PFNMAP), because we have no valid struct
+	 * page backing a VM_PFNMAP range. See also commit a9ff785e4437.
+	 */
+	if (vma->vm_flags & VM_PFNMAP) {
+		walk->skip = 1;
+		return err;
+	}
+
+	if (walk->test_walk)
+		err = walk->test_walk(start, end, walk);
+
+	return err;
+}
+
+static int __walk_page_range(unsigned long start, unsigned long end,
+			struct mm_walk *walk)
+{
+	int err = 0;
+	struct vm_area_struct *vma = walk->vma;
+
+	if (vma && is_vm_hugetlb_page(vma)) {
+		if (walk->hugetlb_entry)
+			err = walk_hugetlb_range(start, end, walk);
+	} else
+		err = walk_pgd_range(start, end, walk);
+
+	return err;
+}
 
 /**
- * walk_page_range - walk a memory map's page tables with a callback
- * @addr: starting address
- * @end: ending address
- * @walk: set of callbacks to invoke for each level of the tree
+ * walk_page_range - walk page table with caller specific callbacks
+ *
+ * Recursively walk the page table tree of the process represented by
+ * @walk->mm within the virtual address range [@start, @end). In walking,
+ * we can call caller-specific callback functions against each entry.
  *
- * Recursively walk the page table for the memory area in a VMA,
- * calling supplied callbacks. Callbacks are called in-order (first
- * PGD, first PUD, first PMD, first PTE, second PTE... second PMD,
- * etc.). If lower-level callbacks are omitted, walking depth is reduced.
+ * Before starting to walk page table, some callers want to check whether
+ * they really want to walk over the vma (for example by checking vm_flags.)
+ * walk_page_test() and @walk->test_walk() do that check.
  *
- * Each callback receives an entry pointer and the start and end of the
- * associated range, and a copy of the original mm_walk for access to
- * the ->private or ->mm fields.
+ * If any callback returns a non-zero value, the page table walk is aborted
+ * immediately and the return value is propagated back to the caller.
+ * Note that the meaning of the positive returned value can be defined
+ * by the caller for its own purpose.
  *
- * Usually no locks are taken, but splitting transparent huge page may
- * take page table lock. And the bottom level iterator will map PTE
- * directories from highmem if necessary.
+ * If the caller defines multiple callbacks in different levels, the
+ * callbacks are called in depth-first manner. It could happen that
+ * multiple callbacks are called on a address. For example if some caller
+ * defines test_walk(), pmd_entry(), and pte_entry(), then callbacks are
+ * called in the order of test_walk(), pmd_entry(), and pte_entry().
+ * If you don't want to go down to lower level at some point and move to
+ * the next entry in the same level, you set @walk->skip to 1.
+ * For example if you succeed to handle some pmd entry as trans_huge entry,
+ * you need not call walk_pte_range() any more, so set it to avoid that.
+ * We can't determine whether to go down to lower level with the return
+ * value of the callback, because the whole range of return values (0, >0,
+ * and <0) are used up for other meanings.
  *
- * If any callback returns a non-zero value, the walk is aborted and
- * the return value is propagated back to the caller. Otherwise 0 is returned.
+ * Each callback can access to the vma over which it is doing page table
+ * walk right now via @walk->vma. @walk->vma is set to NULL in walking
+ * outside a vma. If you want to access to some caller-specific data from
+ * callbacks, @walk->private should be helpful.
  *
- * walk->mm->mmap_sem must be held for at least read if walk->hugetlb_entry
- * is !NULL.
+ * The callers should hold @walk->mm->mmap_sem. Note that the lower level
+ * iterators can take page table lock in lowest level iteration and/or
+ * in split_huge_page_pmd().
  */
-int walk_page_range(unsigned long addr, unsigned long end,
+int walk_page_range(unsigned long start, unsigned long end,
 		    struct mm_walk *walk)
 {
-	pgd_t *pgd;
-	unsigned long next;
 	int err = 0;
+	struct vm_area_struct *vma;
+	unsigned long next;
 
-	if (addr >= end)
-		return err;
+	if (start >= end)
+		return -EINVAL;
 
 	if (!walk->mm)
 		return -EINVAL;
 
+	/* move down_read(&mm->mmap_sem) here? -> NO, caller should do this */
 	VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem));
 
-	pgd = pgd_offset(walk->mm, addr);
 	do {
-		struct vm_area_struct *vma = NULL;
-
-		next = pgd_addr_end(addr, end);
-
-		/*
-		 * This function was not intended to be vma based.
-		 * But there are vma special cases to be handled:
-		 * - hugetlb vma's
-		 * - VM_PFNMAP vma's
-		 */
-		vma = find_vma(walk->mm, addr);
-		if (vma) {
-			/*
-			 * There are no page structures backing a VM_PFNMAP
-			 * range, so do not allow split_huge_page_pmd().
-			 */
-			if ((vma->vm_start <= addr) &&
-			    (vma->vm_flags & VM_PFNMAP)) {
-				next = vma->vm_end;
-				pgd = pgd_offset(walk->mm, next);
-				continue;
-			}
-			/*
-			 * Handle hugetlb vma individually because pagetable
-			 * walk for the hugetlb page is dependent on the
-			 * architecture and we can't handled it in the same
-			 * manner as non-huge pages.
-			 */
-			if (walk->hugetlb_entry && (vma->vm_start <= addr) &&
-			    is_vm_hugetlb_page(vma)) {
-				if (vma->vm_end < next)
-					next = vma->vm_end;
-				/*
-				 * Hugepage is very tightly coupled with vma,
-				 * so walk through hugetlb entries within a
-				 * given vma.
-				 */
-				err = walk_hugetlb_range(vma, addr, next, walk);
-				if (err)
-					break;
-				pgd = pgd_offset(walk->mm, next);
+		vma = find_vma(walk->mm, start);
+		if (!vma) { /* after the last vma */
+			walk->vma = NULL;
+			next = end;
+		} else if (start < vma->vm_start) { /* outside the found vma */
+			walk->vma = NULL;
+			next = vma->vm_start;
+		} else { /* inside the found vma */
+			walk->vma = vma;
+			next = vma->vm_end;
+			err = walk_page_test(start, end, walk);
+			if (walk->skip) {
+				walk->skip = 0;
 				continue;
 			}
-		}
-
-		if (pgd_none_or_clear_bad(pgd)) {
-			if (walk->pte_hole)
-				err = walk->pte_hole(addr, next, walk);
 			if (err)
 				break;
-			pgd++;
-			continue;
 		}
-		if (walk->pgd_entry)
-			err = walk->pgd_entry(pgd, addr, next, walk);
-		if (!err &&
-		    (walk->pud_entry || walk->pmd_entry || walk->pte_entry))
-			err = walk_pud_range(pgd, addr, next, walk);
+		err = __walk_page_range(start, next, walk);
 		if (err)
 			break;
-		pgd++;
-	} while (addr = next, addr != end);
-
+	} while (start = next, start < end);
 	return err;
 }
-- 
1.8.3.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 02/11] pagewalk: add walk_page_vma()

[Naoya Horiguchi]

Introduces walk_page_vma(), which is useful for the callers which
want to walk over a given vma. It's used by later patches.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 include/linux/mm.h |  1 +
 mm/pagewalk.c      | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git v3.12-rc4.orig/include/linux/mm.h v3.12-rc4/include/linux/mm.h
index bd87065..6c138d7 100644
--- v3.12-rc4.orig/include/linux/mm.h
+++ v3.12-rc4/include/linux/mm.h
@@ -979,6 +979,7 @@ struct mm_walk {
 
 int walk_page_range(unsigned long addr, unsigned long end,
 		struct mm_walk *walk);
+int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk);
 void free_pgd_range(struct mmu_gather *tlb, unsigned long addr,
 		unsigned long end, unsigned long floor, unsigned long ceiling);
 int copy_page_range(struct mm_struct *dst, struct mm_struct *src,
diff --git v3.12-rc4.orig/mm/pagewalk.c v3.12-rc4/mm/pagewalk.c
index 9e95541..80b247b 100644
--- v3.12-rc4.orig/mm/pagewalk.c
+++ v3.12-rc4/mm/pagewalk.c
@@ -314,3 +314,23 @@ int walk_page_range(unsigned long start, unsigned long end,
 	} while (start = next, start < end);
 	return err;
 }
+
+int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk)
+{
+	int err;
+
+	if (!walk->mm)
+		return -EINVAL;
+
+	VM_BUG_ON(!rwsem_is_locked(&walk->mm->mmap_sem));
+	VM_BUG_ON(!vma);
+	walk->vma = vma;
+	err = walk_page_test(vma->vm_start, vma->vm_end, walk);
+	if (walk->skip) {
+		walk->skip = 0;
+		return 0;
+	}
+	if (err)
+		return err;
+	return __walk_page_range(vma->vm_start, vma->vm_end, walk);
+}
-- 
1.8.3.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 03/11] smaps: redefine callback functions for page table walker

[Naoya Horiguchi]

smaps_pte_range() connected to pmd_entry() does both of pmd loop and pte loop.
So this patch moves pte part into smaps_pte() on pte_entry() as expected by
the name.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 fs/proc/task_mmu.c | 48 +++++++++++++++++-------------------------------
 1 file changed, 17 insertions(+), 31 deletions(-)

diff --git v3.12-rc4.orig/fs/proc/task_mmu.c v3.12-rc4/fs/proc/task_mmu.c
index c591928..c88ee95 100644
--- v3.12-rc4.orig/fs/proc/task_mmu.c
+++ v3.12-rc4/fs/proc/task_mmu.c
@@ -430,7 +430,6 @@ const struct file_operations proc_tid_maps_operations = {
 
 #ifdef CONFIG_PROC_PAGE_MONITOR
 struct mem_size_stats {
-	struct vm_area_struct *vma;
 	unsigned long resident;
 	unsigned long shared_clean;
 	unsigned long shared_dirty;
@@ -444,15 +443,16 @@ struct mem_size_stats {
 	u64 pss;
 };
 
-
-static void smaps_pte_entry(pte_t ptent, unsigned long addr,
-		unsigned long ptent_size, struct mm_walk *walk)
+static int smaps_pte(pte_t *pte, unsigned long addr, unsigned long end,
+			struct mm_walk *walk)
 {
 	struct mem_size_stats *mss = walk->private;
-	struct vm_area_struct *vma = mss->vma;
+	struct vm_area_struct *vma = walk->vma;
 	pgoff_t pgoff = linear_page_index(vma, addr);
 	struct page *page = NULL;
 	int mapcount;
+	pte_t ptent = *pte;
+	unsigned long ptent_size = end - addr;
 
 	if (pte_present(ptent)) {
 		page = vm_normal_page(vma, addr, ptent);
@@ -469,7 +469,7 @@ static void smaps_pte_entry(pte_t ptent, unsigned long addr,
 	}
 
 	if (!page)
-		return;
+		return 0;
 
 	if (PageAnon(page))
 		mss->anonymous += ptent_size;
@@ -495,35 +495,21 @@ static void smaps_pte_entry(pte_t ptent, unsigned long addr,
 			mss->private_clean += ptent_size;
 		mss->pss += (ptent_size << PSS_SHIFT);
 	}
+	return 0;
 }
 
-static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
-			   struct mm_walk *walk)
+static int smaps_pmd(pmd_t *pmd, unsigned long addr, unsigned long end,
+			struct mm_walk *walk)
 {
 	struct mem_size_stats *mss = walk->private;
-	struct vm_area_struct *vma = mss->vma;
-	pte_t *pte;
-	spinlock_t *ptl;
 
-	if (pmd_trans_huge_lock(pmd, vma) == 1) {
-		smaps_pte_entry(*(pte_t *)pmd, addr, HPAGE_PMD_SIZE, walk);
+	if (pmd_trans_huge_lock(pmd, walk->vma) == 1) {
+		smaps_pte((pte_t *)pmd, addr, addr + HPAGE_PMD_SIZE, walk);
 		spin_unlock(&walk->mm->page_table_lock);
 		mss->anonymous_thp += HPAGE_PMD_SIZE;
-		return 0;
+		/* don't call smaps_pte() */
+		walk->skip = 1;
 	}
-
-	if (pmd_trans_unstable(pmd))
-		return 0;
-	/*
-	 * The mmap_sem held all the way back in m_start() is what
-	 * keeps khugepaged out of here and from collapsing things
-	 * in here.
-	 */
-	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
-	for (; addr != end; pte++, addr += PAGE_SIZE)
-		smaps_pte_entry(*pte, addr, PAGE_SIZE, walk);
-	pte_unmap_unlock(pte - 1, ptl);
-	cond_resched();
 	return 0;
 }
 
@@ -588,16 +574,16 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
 	struct vm_area_struct *vma = v;
 	struct mem_size_stats mss;
 	struct mm_walk smaps_walk = {
-		.pmd_entry = smaps_pte_range,
+		.pmd_entry = smaps_pmd,
+		.pte_entry = smaps_pte,
 		.mm = vma->vm_mm,
+		.vma = vma,
 		.private = &mss,
 	};
 
 	memset(&mss, 0, sizeof mss);
-	mss.vma = vma;
 	/* mmap_sem is held in m_start */
-	if (vma->vm_mm && !is_vm_hugetlb_page(vma))
-		walk_page_range(vma->vm_start, vma->vm_end, &smaps_walk);
+	walk_page_vma(vma, &smaps_walk);
 
 	show_map_vma(m, vma, is_pid);
 
-- 
1.8.3.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 04/11] clear_refs: redefine callback functions for page table walker

[Naoya Horiguchi]

Currently clear_refs_pte_range() is connected to pmd_entry() to split thps
if found. But now this work can be done in core page table walker code.
So we have no reason to keep this callback on pmd_entry(). This patch moves
pte handling code on pte_entry() callback.

clear_refs_write() has some prechecks about if we really walk over a given
vma. It's fine to let them done by test_walk() callback, so let's define it.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 fs/proc/task_mmu.c | 82 ++++++++++++++++++++++--------------------------------
 1 file changed, 33 insertions(+), 49 deletions(-)

diff --git v3.12-rc4.orig/fs/proc/task_mmu.c v3.12-rc4/fs/proc/task_mmu.c
index c88ee95..4abe883 100644
--- v3.12-rc4.orig/fs/proc/task_mmu.c
+++ v3.12-rc4/fs/proc/task_mmu.c
@@ -704,7 +704,6 @@ enum clear_refs_types {
 };
 
 struct clear_refs_private {
-	struct vm_area_struct *vma;
 	enum clear_refs_types type;
 };
 
@@ -736,41 +735,43 @@ static inline void clear_soft_dirty(struct vm_area_struct *vma,
 #endif
 }
 
-static int clear_refs_pte_range(pmd_t *pmd, unsigned long addr,
+static int clear_refs_pte(pte_t *pte, unsigned long addr,
 				unsigned long end, struct mm_walk *walk)
 {
 	struct clear_refs_private *cp = walk->private;
-	struct vm_area_struct *vma = cp->vma;
-	pte_t *pte, ptent;
-	spinlock_t *ptl;
+	struct vm_area_struct *vma = walk->vma;
 	struct page *page;
 
-	split_huge_page_pmd(vma, addr, pmd);
-	if (pmd_trans_unstable(pmd))
+	if (cp->type == CLEAR_REFS_SOFT_DIRTY) {
+		clear_soft_dirty(vma, addr, pte);
 		return 0;
+	}
+	if (!pte_present(*pte))
+		return 0;
+	page = vm_normal_page(vma, addr, *pte);
+	if (!page)
+		return 0;
+	/* Clear accessed and referenced bits. */
+	ptep_test_and_clear_young(vma, addr, pte);
+	ClearPageReferenced(page);
+	return 0;
+}
 
-	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
-	for (; addr != end; pte++, addr += PAGE_SIZE) {
-		ptent = *pte;
-
-		if (cp->type == CLEAR_REFS_SOFT_DIRTY) {
-			clear_soft_dirty(vma, addr, pte);
-			continue;
-		}
-
-		if (!pte_present(ptent))
-			continue;
-
-		page = vm_normal_page(vma, addr, ptent);
-		if (!page)
-			continue;
+static int clear_refs_test_walk(unsigned long start, unsigned long end,
+				struct mm_walk *walk)
+{
+	struct clear_refs_private *cp = walk->private;
+	struct vm_area_struct *vma = walk->vma;
 
-		/* Clear accessed and referenced bits. */
-		ptep_test_and_clear_young(vma, addr, pte);
-		ClearPageReferenced(page);
-	}
-	pte_unmap_unlock(pte - 1, ptl);
-	cond_resched();
+	/*
+	 * Writing 1 to /proc/pid/clear_refs affects all pages.
+	 * Writing 2 to /proc/pid/clear_refs only affects anonymous pages.
+	 * Writing 3 to /proc/pid/clear_refs only affects file mapped pages.
+	 */
+	if (cp->type == CLEAR_REFS_ANON && vma->vm_file)
+		walk->skip = 1;
+	if (cp->type == CLEAR_REFS_MAPPED && !vma->vm_file)
+		walk->skip = 1;
 	return 0;
 }
 
@@ -812,33 +813,16 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
 			.type = type,
 		};
 		struct mm_walk clear_refs_walk = {
-			.pmd_entry = clear_refs_pte_range,
+			.pte_entry = clear_refs_pte,
+			.test_walk = clear_refs_test_walk,
 			.mm = mm,
 			.private = &cp,
 		};
 		down_read(&mm->mmap_sem);
 		if (type == CLEAR_REFS_SOFT_DIRTY)
 			mmu_notifier_invalidate_range_start(mm, 0, -1);
-		for (vma = mm->mmap; vma; vma = vma->vm_next) {
-			cp.vma = vma;
-			if (is_vm_hugetlb_page(vma))
-				continue;
-			/*
-			 * Writing 1 to /proc/pid/clear_refs affects all pages.
-			 *
-			 * Writing 2 to /proc/pid/clear_refs only affects
-			 * Anonymous pages.
-			 *
-			 * Writing 3 to /proc/pid/clear_refs only affects file
-			 * mapped pages.
-			 */
-			if (type == CLEAR_REFS_ANON && vma->vm_file)
-				continue;
-			if (type == CLEAR_REFS_MAPPED && !vma->vm_file)
-				continue;
-			walk_page_range(vma->vm_start, vma->vm_end,
-					&clear_refs_walk);
-		}
+		for (vma = mm->mmap; vma; vma = vma->vm_next)
+			walk_page_vma(vma, &clear_refs_walk);
 		if (type == CLEAR_REFS_SOFT_DIRTY)
 			mmu_notifier_invalidate_range_end(mm, 0, -1);
 		flush_tlb_mm(mm);
-- 
1.8.3.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 05/11] pagemap: redefine callback functions for page table walker

[Naoya Horiguchi]

pagemap_pte_range() connected to pmd_entry() does both of pmd loop and
pte loop. So this patch moves pte part into pagemap_pte() on pte_entry().

We remove VM_SOFTDIRTY check in pagemap_pte_range(), because in the new
page table walker we call __walk_page_range() for each vma separately,
so we never experience multiple vmas in single pgd/pud/pmd/pte loop.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 fs/proc/task_mmu.c | 71 +++++++++++++++++++++---------------------------------
 1 file changed, 27 insertions(+), 44 deletions(-)

diff --git v3.12-rc4.orig/fs/proc/task_mmu.c v3.12-rc4/fs/proc/task_mmu.c
index 4abe883..21e5828 100644
--- v3.12-rc4.orig/fs/proc/task_mmu.c
+++ v3.12-rc4/fs/proc/task_mmu.c
@@ -961,18 +961,32 @@ static inline void thp_pmd_to_pagemap_entry(pagemap_entry_t *pme, struct pagemap
 }
 #endif
 
-static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
+static int pagemap_pte(pte_t *pte, unsigned long addr, unsigned long end,
 			     struct mm_walk *walk)
 {
-	struct vm_area_struct *vma;
+	struct vm_area_struct *vma = walk->vma;
 	struct pagemapread *pm = walk->private;
-	pte_t *pte;
+	pagemap_entry_t pme = make_pme(PM_NOT_PRESENT(pm->v2));
+
+	if (vma && vma->vm_start <= addr && end <= vma->vm_end) {
+		pte_to_pagemap_entry(&pme, pm, vma, addr, *pte);
+		/* unmap before userspace copy */
+		pte_unmap(pte);
+	}
+	return add_to_pagemap(addr, &pme, pm);
+}
+
+static int pagemap_pmd(pmd_t *pmd, unsigned long addr, unsigned long end,
+			     struct mm_walk *walk)
+{
 	int err = 0;
+	struct vm_area_struct *vma = walk->vma;
+	struct pagemapread *pm = walk->private;
 	pagemap_entry_t pme = make_pme(PM_NOT_PRESENT(pm->v2));
 
-	/* find the first VMA at or above 'addr' */
-	vma = find_vma(walk->mm, addr);
-	if (vma && pmd_trans_huge_lock(pmd, vma) == 1) {
+	if (!vma)
+		return err;
+	if (pmd_trans_huge_lock(pmd, vma) == 1) {
 		int pmd_flags2;
 
 		if ((vma->vm_flags & VM_SOFTDIRTY) || pmd_soft_dirty(*pmd))
@@ -991,41 +1005,9 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 				break;
 		}
 		spin_unlock(&walk->mm->page_table_lock);
-		return err;
-	}
-
-	if (pmd_trans_unstable(pmd))
-		return 0;
-	for (; addr != end; addr += PAGE_SIZE) {
-		int flags2;
-
-		/* check to see if we've left 'vma' behind
-		 * and need a new, higher one */
-		if (vma && (addr >= vma->vm_end)) {
-			vma = find_vma(walk->mm, addr);
-			if (vma && (vma->vm_flags & VM_SOFTDIRTY))
-				flags2 = __PM_SOFT_DIRTY;
-			else
-				flags2 = 0;
-			pme = make_pme(PM_NOT_PRESENT(pm->v2) | PM_STATUS2(pm->v2, flags2));
-		}
-
-		/* check that 'vma' actually covers this address,
-		 * and that it isn't a huge page vma */
-		if (vma && (vma->vm_start <= addr) &&
-		    !is_vm_hugetlb_page(vma)) {
-			pte = pte_offset_map(pmd, addr);
-			pte_to_pagemap_entry(&pme, pm, vma, addr, *pte);
-			/* unmap before userspace copy */
-			pte_unmap(pte);
-		}
-		err = add_to_pagemap(addr, &pme, pm);
-		if (err)
-			return err;
+		/* don't call pagemap_pte() */
+		walk->skip = 1;
 	}
-
-	cond_resched();
-
 	return err;
 }
 
@@ -1048,12 +1030,11 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
 				 struct mm_walk *walk)
 {
 	struct pagemapread *pm = walk->private;
-	struct vm_area_struct *vma;
+	struct vm_area_struct *vma = walk->vma;
 	int err = 0;
 	int flags2;
 	pagemap_entry_t pme;
 
-	vma = find_vma(walk->mm, addr);
 	WARN_ON_ONCE(!vma);
 
 	if (vma && (vma->vm_flags & VM_SOFTDIRTY))
@@ -1061,6 +1042,7 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
 	else
 		flags2 = 0;
 
+	hmask = huge_page_mask(hstate_vma(vma));
 	for (; addr != end; addr += PAGE_SIZE) {
 		int offset = (addr & ~hmask) >> PAGE_SHIFT;
 		huge_pte_to_pagemap_entry(&pme, pm, *pte, offset, flags2);
@@ -1137,10 +1119,11 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
 	if (!mm || IS_ERR(mm))
 		goto out_free;
 
-	pagemap_walk.pmd_entry = pagemap_pte_range;
+	pagemap_walk.pte_entry = pagemap_pte;
+	pagemap_walk.pmd_entry = pagemap_pmd;
 	pagemap_walk.pte_hole = pagemap_pte_hole;
 #ifdef CONFIG_HUGETLB_PAGE
-	pagemap_walk.hugetlb_entry = pagemap_hugetlb_range;
+	pagemap_walk.hugetlb_entry = pagemap_hugetlb;
 #endif
 	pagemap_walk.mm = mm;
 	pagemap_walk.private = &pm;
-- 
1.8.3.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 06/11] numa_maps: redefine callback functions for page table walker

[Naoya Horiguchi]

gather_pte_stats() connected to pmd_entry() does both of pmd loop and
pte loop. So this patch moves pte part into pte_entry().

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 fs/proc/task_mmu.c | 53 +++++++++++++++++++++++++----------------------------
 1 file changed, 25 insertions(+), 28 deletions(-)

diff --git v3.12-rc4.orig/fs/proc/task_mmu.c v3.12-rc4/fs/proc/task_mmu.c
index 21e5828..e3e03bc 100644
--- v3.12-rc4.orig/fs/proc/task_mmu.c
+++ v3.12-rc4/fs/proc/task_mmu.c
@@ -1199,7 +1199,6 @@ const struct file_operations proc_pagemap_operations = {
 #ifdef CONFIG_NUMA
 
 struct numa_maps {
-	struct vm_area_struct *vma;
 	unsigned long pages;
 	unsigned long anon;
 	unsigned long active;
@@ -1265,43 +1264,40 @@ static struct page *can_gather_numa_stats(pte_t pte, struct vm_area_struct *vma,
 	return page;
 }
 
-static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
+static int gather_pte_stats(pte_t *pte, unsigned long addr,
 		unsigned long end, struct mm_walk *walk)
 {
-	struct numa_maps *md;
-	spinlock_t *ptl;
-	pte_t *orig_pte;
-	pte_t *pte;
+	struct numa_maps *md = walk->private;
 
-	md = walk->private;
+	struct page *page = can_gather_numa_stats(*pte, walk->vma, addr);
+	if (!page)
+		return 0;
+	gather_stats(page, md, pte_dirty(*pte), 1);
+	return 0;
+}
+
+static int gather_pmd_stats(pmd_t *pmd, unsigned long addr,
+		unsigned long end, struct mm_walk *walk)
+{
+	struct numa_maps *md = walk->private;
+	struct vm_area_struct *vma = walk->vma;
 
-	if (pmd_trans_huge_lock(pmd, md->vma) == 1) {
+	if (pmd_trans_huge_lock(pmd, vma) == 1) {
 		pte_t huge_pte = *(pte_t *)pmd;
 		struct page *page;
 
-		page = can_gather_numa_stats(huge_pte, md->vma, addr);
+		page = can_gather_numa_stats(huge_pte, vma, addr);
 		if (page)
 			gather_stats(page, md, pte_dirty(huge_pte),
 				     HPAGE_PMD_SIZE/PAGE_SIZE);
 		spin_unlock(&walk->mm->page_table_lock);
-		return 0;
+		/* don't call gather_pte_stats() */
+		walk->skip = 1;
 	}
-
-	if (pmd_trans_unstable(pmd))
-		return 0;
-	orig_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
-	do {
-		struct page *page = can_gather_numa_stats(*pte, md->vma, addr);
-		if (!page)
-			continue;
-		gather_stats(page, md, pte_dirty(*pte), 1);
-
-	} while (pte++, addr += PAGE_SIZE, addr != end);
-	pte_unmap_unlock(orig_pte, ptl);
 	return 0;
 }
 #ifdef CONFIG_HUGETLB_PAGE
-static int gather_hugetbl_stats(pte_t *pte, unsigned long hmask,
+static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
 		unsigned long addr, unsigned long end, struct mm_walk *walk)
 {
 	struct numa_maps *md;
@@ -1320,7 +1316,7 @@ static int gather_hugetbl_stats(pte_t *pte, unsigned long hmask,
 }
 
 #else
-static int gather_hugetbl_stats(pte_t *pte, unsigned long hmask,
+static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
 		unsigned long addr, unsigned long end, struct mm_walk *walk)
 {
 	return 0;
@@ -1350,12 +1346,12 @@ static int show_numa_map(struct seq_file *m, void *v, int is_pid)
 	/* Ensure we start with an empty set of numa_maps statistics. */
 	memset(md, 0, sizeof(*md));
 
-	md->vma = vma;
-
-	walk.hugetlb_entry = gather_hugetbl_stats;
-	walk.pmd_entry = gather_pte_stats;
+	walk.hugetlb_entry = gather_hugetlb_stats;
+	walk.pmd_entry = gather_pmd_stats;
+	walk.pte_entry = gather_pte_stats;
 	walk.private = md;
 	walk.mm = mm;
+	walk.vma = vma;
 
 	pol = get_vma_policy(task, vma, vma->vm_start);
 	n = mpol_to_str(buffer, sizeof(buffer), pol);
@@ -1388,6 +1384,7 @@ static int show_numa_map(struct seq_file *m, void *v, int is_pid)
 	if (is_vm_hugetlb_page(vma))
 		seq_printf(m, " huge");
 
+	/* mmap_sem is held by m_start */
 	walk_page_range(vma->vm_start, vma->vm_end, &walk);
 
 	if (!md->pages)
-- 
1.8.3.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 07/11] memcg: redefine callback functions for page table walker

[Naoya Horiguchi]

Move code around pte loop in mem_cgroup_count_precharge_pte_range() into
mem_cgroup_count_precharge_pte() connected to pte_entry().

We don't change the callback mem_cgroup_move_charge_pte_range() for now,
because we can't do the same replacement easily due to 'goto retry'.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 mm/memcontrol.c | 72 ++++++++++++++++++++++-----------------------------------
 1 file changed, 27 insertions(+), 45 deletions(-)

diff --git v3.12-rc4.orig/mm/memcontrol.c v3.12-rc4/mm/memcontrol.c
index 1c52ddb..a0ea918 100644
--- v3.12-rc4.orig/mm/memcontrol.c
+++ v3.12-rc4/mm/memcontrol.c
@@ -6621,30 +6621,28 @@ static inline enum mc_target_type get_mctgt_type_thp(struct vm_area_struct *vma,
 }
 #endif
 
-static int mem_cgroup_count_precharge_pte_range(pmd_t *pmd,
+static int mem_cgroup_count_precharge_pte(pte_t *pte,
 					unsigned long addr, unsigned long end,
 					struct mm_walk *walk)
 {
-	struct vm_area_struct *vma = walk->private;
-	pte_t *pte;
-	spinlock_t *ptl;
+	if (get_mctgt_type(walk->vma, addr, *pte, NULL))
+		mc.precharge++;	/* increment precharge temporarily */
+	return 0;
+}
+
+static int mem_cgroup_count_precharge_pmd(pmd_t *pmd,
+					unsigned long addr, unsigned long end,
+					struct mm_walk *walk)
+{
+	struct vm_area_struct *vma = walk->vma;
 
 	if (pmd_trans_huge_lock(pmd, vma) == 1) {
 		if (get_mctgt_type_thp(vma, addr, *pmd, NULL) == MC_TARGET_PAGE)
 			mc.precharge += HPAGE_PMD_NR;
 		spin_unlock(&vma->vm_mm->page_table_lock);
-		return 0;
+		/* don't call mem_cgroup_count_precharge_pte() */
+		walk->skip = 1;
 	}
-
-	if (pmd_trans_unstable(pmd))
-		return 0;
-	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
-	for (; addr != end; pte++, addr += PAGE_SIZE)
-		if (get_mctgt_type(vma, addr, *pte, NULL))
-			mc.precharge++;	/* increment precharge temporarily */
-	pte_unmap_unlock(pte - 1, ptl);
-	cond_resched();
-
 	return 0;
 }
 
@@ -6653,18 +6651,14 @@ static unsigned long mem_cgroup_count_precharge(struct mm_struct *mm)
 	unsigned long precharge;
 	struct vm_area_struct *vma;
 
+	struct mm_walk mem_cgroup_count_precharge_walk = {
+		.pmd_entry = mem_cgroup_count_precharge_pmd,
+		.pte_entry = mem_cgroup_count_precharge_pte,
+		.mm = mm,
+	};
 	down_read(&mm->mmap_sem);
-	for (vma = mm->mmap; vma; vma = vma->vm_next) {
-		struct mm_walk mem_cgroup_count_precharge_walk = {
-			.pmd_entry = mem_cgroup_count_precharge_pte_range,
-			.mm = mm,
-			.private = vma,
-		};
-		if (is_vm_hugetlb_page(vma))
-			continue;
-		walk_page_range(vma->vm_start, vma->vm_end,
-					&mem_cgroup_count_precharge_walk);
-	}
+	for (vma = mm->mmap; vma; vma = vma->vm_next)
+		walk_page_vma(vma, &mem_cgroup_count_precharge_walk);
 	up_read(&mm->mmap_sem);
 
 	precharge = mc.precharge;
@@ -6803,7 +6797,7 @@ static int mem_cgroup_move_charge_pte_range(pmd_t *pmd,
 				struct mm_walk *walk)
 {
 	int ret = 0;
-	struct vm_area_struct *vma = walk->private;
+	struct vm_area_struct *vma = walk->vma;
 	pte_t *pte;
 	spinlock_t *ptl;
 	enum mc_target_type target_type;
@@ -6904,6 +6898,10 @@ put:			/* get_mctgt_type() gets the page */
 static void mem_cgroup_move_charge(struct mm_struct *mm)
 {
 	struct vm_area_struct *vma;
+	struct mm_walk mem_cgroup_move_charge_walk = {
+		.pmd_entry = mem_cgroup_move_charge_pte_range,
+		.mm = mm,
+	};
 
 	lru_add_drain_all();
 retry:
@@ -6919,24 +6917,8 @@ static void mem_cgroup_move_charge(struct mm_struct *mm)
 		cond_resched();
 		goto retry;
 	}
-	for (vma = mm->mmap; vma; vma = vma->vm_next) {
-		int ret;
-		struct mm_walk mem_cgroup_move_charge_walk = {
-			.pmd_entry = mem_cgroup_move_charge_pte_range,
-			.mm = mm,
-			.private = vma,
-		};
-		if (is_vm_hugetlb_page(vma))
-			continue;
-		ret = walk_page_range(vma->vm_start, vma->vm_end,
-						&mem_cgroup_move_charge_walk);
-		if (ret)
-			/*
-			 * means we have consumed all precharges and failed in
-			 * doing additional charge. Just abandon here.
-			 */
-			break;
-	}
+	for (vma = mm->mmap; vma; vma = vma->vm_next)
+		walk_page_vma(vma, &mem_cgroup_move_charge_walk);
 	up_read(&mm->mmap_sem);
 }
 
-- 
1.8.3.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 08/11] madvise: redefine callback functions for page table walker

[Naoya Horiguchi]

swapin_walk_pmd_entry() is defined as pmd_entry(), but it has no code
about pmd handling (except pmd_none_or_trans_huge_or_clear_bad, but the
same check are now done in core page table walk code).
So let's move this function on pte_entry() as swapin_walk_pte_entry().

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 mm/madvise.c | 43 +++++++++++++------------------------------
 1 file changed, 13 insertions(+), 30 deletions(-)

diff --git v3.12-rc4.orig/mm/madvise.c v3.12-rc4/mm/madvise.c
index 539eeb9..5e957b9 100644
--- v3.12-rc4.orig/mm/madvise.c
+++ v3.12-rc4/mm/madvise.c
@@ -135,38 +135,22 @@ static long madvise_behavior(struct vm_area_struct *vma,
 }
 
 #ifdef CONFIG_SWAP
-static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
+static int swapin_walk_pte_entry(pte_t *pte, unsigned long start,
 	unsigned long end, struct mm_walk *walk)
 {
-	pte_t *orig_pte;
-	struct vm_area_struct *vma = walk->private;
-	unsigned long index;
+	swp_entry_t entry;
+	struct page *page;
+	struct vm_area_struct *vma = walk->vma;
 
-	if (pmd_none_or_trans_huge_or_clear_bad(pmd))
+	if (pte_present(*pte) || pte_none(*pte) || pte_file(*pte))
 		return 0;
-
-	for (index = start; index != end; index += PAGE_SIZE) {
-		pte_t pte;
-		swp_entry_t entry;
-		struct page *page;
-		spinlock_t *ptl;
-
-		orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
-		pte = *(orig_pte + ((index - start) / PAGE_SIZE));
-		pte_unmap_unlock(orig_pte, ptl);
-
-		if (pte_present(pte) || pte_none(pte) || pte_file(pte))
-			continue;
-		entry = pte_to_swp_entry(pte);
-		if (unlikely(non_swap_entry(entry)))
-			continue;
-
-		page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
-								vma, index);
-		if (page)
-			page_cache_release(page);
-	}
-
+	entry = pte_to_swp_entry(*pte);
+	if (unlikely(non_swap_entry(entry)))
+		return 0;
+	page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
+				     vma, start);
+	if (page)
+		page_cache_release(page);
 	return 0;
 }
 
@@ -175,8 +159,7 @@ static void force_swapin_readahead(struct vm_area_struct *vma,
 {
 	struct mm_walk walk = {
 		.mm = vma->vm_mm,
-		.pmd_entry = swapin_walk_pmd_entry,
-		.private = vma,
+		.pte_entry = swapin_walk_pte_entry,
 	};
 
 	walk_page_range(start, end, &walk);
-- 
1.8.3.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 09/11] arch/powerpc/mm/subpage-prot.c: use walk_page_vma() instead of walk_page_range()

[Naoya Horiguchi]

We don't have to use mm_walk->private to pass vma to the callback
function, because mm_walk->vma is automatically set to the valid one.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 arch/powerpc/mm/subpage-prot.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git v3.12-rc4.orig/arch/powerpc/mm/subpage-prot.c v3.12-rc4/arch/powerpc/mm/subpage-prot.c
index a770df2d..cec0af0 100644
--- v3.12-rc4.orig/arch/powerpc/mm/subpage-prot.c
+++ v3.12-rc4/arch/powerpc/mm/subpage-prot.c
@@ -134,7 +134,7 @@ static void subpage_prot_clear(unsigned long addr, unsigned long len)
 static int subpage_walk_pmd_entry(pmd_t *pmd, unsigned long addr,
 				  unsigned long end, struct mm_walk *walk)
 {
-	struct vm_area_struct *vma = walk->private;
+	struct vm_area_struct *vma = walk->vma;
 	split_huge_page_pmd(vma, addr, pmd);
 	return 0;
 }
@@ -163,9 +163,7 @@ static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,
 		if (vma->vm_start >= (addr + len))
 			break;
 		vma->vm_flags |= VM_NOHUGEPAGE;
-		subpage_proto_walk.private = vma;
-		walk_page_range(vma->vm_start, vma->vm_end,
-				&subpage_proto_walk);
+		walk_page_vma(vma, &subpage_proto_walk);
 		vma = vma->vm_next;
 	}
 }
-- 
1.8.3.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 10/11] pagewalk: remove argument hmask from hugetlb_entry()

[Naoya Horiguchi]

All of callbacks connected to hugetlb_entry() are changed not to
use the argument hmask. So we can remove it now.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 fs/proc/task_mmu.c | 12 ++++++------
 include/linux/mm.h |  5 ++---
 mm/pagewalk.c      |  2 +-
 3 files changed, 9 insertions(+), 10 deletions(-)

diff --git v3.12-rc4.orig/fs/proc/task_mmu.c v3.12-rc4/fs/proc/task_mmu.c
index e3e03bc..aefe239 100644
--- v3.12-rc4.orig/fs/proc/task_mmu.c
+++ v3.12-rc4/fs/proc/task_mmu.c
@@ -1025,8 +1025,7 @@ static void huge_pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *
 }
 
 /* This function walks within one hugetlb entry in the single call */
-static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
-				 unsigned long addr, unsigned long end,
+static int pagemap_hugetlb(pte_t *pte, unsigned long addr, unsigned long end,
 				 struct mm_walk *walk)
 {
 	struct pagemapread *pm = walk->private;
@@ -1034,6 +1033,7 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
 	int err = 0;
 	int flags2;
 	pagemap_entry_t pme;
+	unsigned long hmask;
 
 	WARN_ON_ONCE(!vma);
 
@@ -1297,8 +1297,8 @@ static int gather_pmd_stats(pmd_t *pmd, unsigned long addr,
 	return 0;
 }
 #ifdef CONFIG_HUGETLB_PAGE
-static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
-		unsigned long addr, unsigned long end, struct mm_walk *walk)
+static int gather_hugetlb_stats(pte_t *pte, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
 {
 	struct numa_maps *md;
 	struct page *page;
@@ -1316,8 +1316,8 @@ static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
 }
 
 #else
-static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
-		unsigned long addr, unsigned long end, struct mm_walk *walk)
+static int gather_hugetlb_stats(pte_t *pte, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
 {
 	return 0;
 }
diff --git v3.12-rc4.orig/include/linux/mm.h v3.12-rc4/include/linux/mm.h
index 6c138d7..04cf32c 100644
--- v3.12-rc4.orig/include/linux/mm.h
+++ v3.12-rc4/include/linux/mm.h
@@ -966,9 +966,8 @@ struct mm_walk {
 			 unsigned long next, struct mm_walk *walk);
 	int (*pte_hole)(unsigned long addr, unsigned long next,
 			struct mm_walk *walk);
-	int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
-			     unsigned long addr, unsigned long next,
-			     struct mm_walk *walk);
+	int (*hugetlb_entry)(pte_t *pte, unsigned long addr,
+			unsigned long next, struct mm_walk *walk);
 	int (*test_walk)(unsigned long addr, unsigned long next,
 			struct mm_walk *walk);
 	struct mm_struct *mm;
diff --git v3.12-rc4.orig/mm/pagewalk.c v3.12-rc4/mm/pagewalk.c
index 80b247b..9437ffc 100644
--- v3.12-rc4.orig/mm/pagewalk.c
+++ v3.12-rc4/mm/pagewalk.c
@@ -182,7 +182,7 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
 		 * in walk->hugetlb_entry().
 		 */
 		if (pte && walk->hugetlb_entry)
-			err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
+			err = walk->hugetlb_entry(pte, addr, next, walk);
 		if (err)
 			break;
 	} while (addr = next, addr != end);
-- 
1.8.3.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 11/11] mempolicy: apply page table walker on queue_pages_range()

[Naoya Horiguchi]

queue_pages_range() does page table walking in its own way now,
so this patch rewrites it with walk_page_range().
One difficulty was that queue_pages_range() need to check vmas
to determine whether we queue pages from a given vma or skip it.
Now we have test_walk() callback in mm_walk for that purpose,
so we can do the replacement cleanly. queue_pages_test_walk()
depends on not only the current vma but also the previous vma,
so we use queue_pages->prev to remember it.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 mm/mempolicy.c | 251 ++++++++++++++++++++++-----------------------------------
 1 file changed, 96 insertions(+), 155 deletions(-)

diff --git v3.12-rc4.orig/mm/mempolicy.c v3.12-rc4/mm/mempolicy.c
index 0472964..2f1889f 100644
--- v3.12-rc4.orig/mm/mempolicy.c
+++ v3.12-rc4/mm/mempolicy.c
@@ -476,139 +476,66 @@ static const struct mempolicy_operations mpol_ops[MPOL_MAX] = {
 static void migrate_page_add(struct page *page, struct list_head *pagelist,
 				unsigned long flags);
 
+struct queue_pages {
+	struct list_head *pagelist;
+	unsigned long flags;
+	nodemask_t *nmask;
+	struct vm_area_struct *prev;
+};
+
 /*
  * Scan through pages checking if pages follow certain conditions,
  * and move them to the pagelist if they do.
  */
-static int queue_pages_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
-		unsigned long addr, unsigned long end,
-		const nodemask_t *nodes, unsigned long flags,
-		void *private)
+static int queue_pages_pte(pte_t *pte, unsigned long addr,
+			unsigned long next, struct mm_walk *walk)
 {
-	pte_t *orig_pte;
-	pte_t *pte;
-	spinlock_t *ptl;
-
-	orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
-	do {
-		struct page *page;
-		int nid;
+	struct vm_area_struct *vma = walk->vma;
+	struct page *page;
+	struct queue_pages *qp = walk->private;
+	unsigned long flags = qp->flags;
+	int nid;
 
-		if (!pte_present(*pte))
-			continue;
-		page = vm_normal_page(vma, addr, *pte);
-		if (!page)
-			continue;
-		/*
-		 * vm_normal_page() filters out zero pages, but there might
-		 * still be PageReserved pages to skip, perhaps in a VDSO.
-		 */
-		if (PageReserved(page))
-			continue;
-		nid = page_to_nid(page);
-		if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT))
-			continue;
+	if (!pte_present(*pte))
+		return 0;
+	page = vm_normal_page(vma, addr, *pte);
+	if (!page)
+		return 0;
+	/*
+	 * vm_normal_page() filters out zero pages, but there might
+	 * still be PageReserved pages to skip, perhaps in a VDSO.
+	 */
+	if (PageReserved(page))
+		return 0;
+	nid = page_to_nid(page);
+	if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
+		return 0;
 
-		if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
-			migrate_page_add(page, private, flags);
-		else
-			break;
-	} while (pte++, addr += PAGE_SIZE, addr != end);
-	pte_unmap_unlock(orig_pte, ptl);
-	return addr != end;
+	if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
+		migrate_page_add(page, qp->pagelist, flags);
+	return 0;
 }
 
-static void queue_pages_hugetlb_pmd_range(struct vm_area_struct *vma,
-		pmd_t *pmd, const nodemask_t *nodes, unsigned long flags,
-				    void *private)
+static int queue_pages_hugetlb(pte_t *pte, unsigned long addr,
+				unsigned long next, struct mm_walk *walk)
 {
 #ifdef CONFIG_HUGETLB_PAGE
+	struct queue_pages *qp = walk->private;
+	unsigned long flags = qp->flags;
 	int nid;
 	struct page *page;
 
-	spin_lock(&vma->vm_mm->page_table_lock);
-	page = pte_page(huge_ptep_get((pte_t *)pmd));
+	page = pte_page(huge_ptep_get(pte));
 	nid = page_to_nid(page);
-	if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT))
-		goto unlock;
+	if (node_isset(nid, *qp->nmask) == !!(flags & MPOL_MF_INVERT))
+		return 0;
 	/* With MPOL_MF_MOVE, we migrate only unshared hugepage. */
 	if (flags & (MPOL_MF_MOVE_ALL) ||
 	    (flags & MPOL_MF_MOVE && page_mapcount(page) == 1))
-		isolate_huge_page(page, private);
-unlock:
-	spin_unlock(&vma->vm_mm->page_table_lock);
+		isolate_huge_page(page, qp->pagelist);
 #else
 	BUG();
 #endif
-}
-
-static inline int queue_pages_pmd_range(struct vm_area_struct *vma, pud_t *pud,
-		unsigned long addr, unsigned long end,
-		const nodemask_t *nodes, unsigned long flags,
-		void *private)
-{
-	pmd_t *pmd;
-	unsigned long next;
-
-	pmd = pmd_offset(pud, addr);
-	do {
-		next = pmd_addr_end(addr, end);
-		if (!pmd_present(*pmd))
-			continue;
-		if (pmd_huge(*pmd) && is_vm_hugetlb_page(vma)) {
-			queue_pages_hugetlb_pmd_range(vma, pmd, nodes,
-						flags, private);
-			continue;
-		}
-		split_huge_page_pmd(vma, addr, pmd);
-		if (pmd_none_or_trans_huge_or_clear_bad(pmd))
-			continue;
-		if (queue_pages_pte_range(vma, pmd, addr, next, nodes,
-				    flags, private))
-			return -EIO;
-	} while (pmd++, addr = next, addr != end);
-	return 0;
-}
-
-static inline int queue_pages_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
-		unsigned long addr, unsigned long end,
-		const nodemask_t *nodes, unsigned long flags,
-		void *private)
-{
-	pud_t *pud;
-	unsigned long next;
-
-	pud = pud_offset(pgd, addr);
-	do {
-		next = pud_addr_end(addr, end);
-		if (pud_huge(*pud) && is_vm_hugetlb_page(vma))
-			continue;
-		if (pud_none_or_clear_bad(pud))
-			continue;
-		if (queue_pages_pmd_range(vma, pud, addr, next, nodes,
-				    flags, private))
-			return -EIO;
-	} while (pud++, addr = next, addr != end);
-	return 0;
-}
-
-static inline int queue_pages_pgd_range(struct vm_area_struct *vma,
-		unsigned long addr, unsigned long end,
-		const nodemask_t *nodes, unsigned long flags,
-		void *private)
-{
-	pgd_t *pgd;
-	unsigned long next;
-
-	pgd = pgd_offset(vma->vm_mm, addr);
-	do {
-		next = pgd_addr_end(addr, end);
-		if (pgd_none_or_clear_bad(pgd))
-			continue;
-		if (queue_pages_pud_range(vma, pgd, addr, next, nodes,
-				    flags, private))
-			return -EIO;
-	} while (pgd++, addr = next, addr != end);
 	return 0;
 }
 
@@ -642,6 +569,42 @@ static unsigned long change_prot_numa(struct vm_area_struct *vma,
 }
 #endif /* CONFIG_ARCH_USES_NUMA_PROT_NONE */
 
+static int queue_pages_test_walk(unsigned long start, unsigned long end,
+				struct mm_walk *walk)
+{
+	struct vm_area_struct *vma = walk->vma;
+	struct queue_pages *qp = walk->private;
+	unsigned long endvma = vma->vm_end;
+	unsigned long flags = qp->flags;
+
+	if (endvma > end)
+		endvma = end;
+	if (vma->vm_start > start)
+		start = vma->vm_start;
+
+	if (!(flags & MPOL_MF_DISCONTIG_OK)) {
+		if (!vma->vm_next && vma->vm_end < end)
+			return -EFAULT;
+		if (qp->prev && qp->prev->vm_end < vma->vm_start)
+			return -EFAULT;
+	}
+
+	qp->prev = vma;
+	walk->skip = 1;
+
+	if (flags & MPOL_MF_LAZY) {
+		change_prot_numa(vma, start, endvma);
+		return 0;
+	}
+
+	if ((flags & MPOL_MF_STRICT) ||
+	    ((flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) &&
+	     vma_migratable(vma)))
+		/* queue pages from current vma */
+		walk->skip = 0;
+	return 0;
+}
+
 /*
  * Walk through page tables and collect pages to be migrated.
  *
@@ -651,51 +614,29 @@ static unsigned long change_prot_numa(struct vm_area_struct *vma,
  */
 static struct vm_area_struct *
 queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end,
-		const nodemask_t *nodes, unsigned long flags, void *private)
+		nodemask_t *nodes, unsigned long flags,
+		struct list_head *pagelist)
 {
 	int err;
-	struct vm_area_struct *first, *vma, *prev;
-
-
-	first = find_vma(mm, start);
-	if (!first)
-		return ERR_PTR(-EFAULT);
-	prev = NULL;
-	for (vma = first; vma && vma->vm_start < end; vma = vma->vm_next) {
-		unsigned long endvma = vma->vm_end;
-
-		if (endvma > end)
-			endvma = end;
-		if (vma->vm_start > start)
-			start = vma->vm_start;
-
-		if (!(flags & MPOL_MF_DISCONTIG_OK)) {
-			if (!vma->vm_next && vma->vm_end < end)
-				return ERR_PTR(-EFAULT);
-			if (prev && prev->vm_end < vma->vm_start)
-				return ERR_PTR(-EFAULT);
-		}
-
-		if (flags & MPOL_MF_LAZY) {
-			change_prot_numa(vma, start, endvma);
-			goto next;
-		}
-
-		if ((flags & MPOL_MF_STRICT) ||
-		     ((flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) &&
-		      vma_migratable(vma))) {
-
-			err = queue_pages_pgd_range(vma, start, endvma, nodes,
-						flags, private);
-			if (err) {
-				first = ERR_PTR(err);
-				break;
-			}
-		}
-next:
-		prev = vma;
-	}
-	return first;
+	struct queue_pages qp = {
+		.pagelist = pagelist,
+		.flags = flags,
+		.nmask = nodes,
+		.prev = NULL,
+	};
+	struct mm_walk queue_pages_walk = {
+		.hugetlb_entry = queue_pages_hugetlb,
+		.pte_entry = queue_pages_pte,
+		.test_walk = queue_pages_test_walk,
+		.mm = mm,
+		.private = &qp,
+	};
+
+	err = walk_page_range(start, end, &queue_pages_walk);
+	if (err < 0)
+		return ERR_PTR(err);
+	else
+		return find_vma(mm, start);
 }
 
 /*
-- 
1.8.3.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH 0/11] update page table walker

[Andrew Morton]

On Mon, 14 Oct 2013 13:36:59 -0400 Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> wrote:

> Page table walker is widely used when you want to traverse page table
> tree and do some work for the entries (and pages pointed to by them.)
> This is a common operation, and keep the code clean and maintainable
> is important. Moreover this patchset introduces caller-specific walk
> control function which is helpful for us to newly introduce page table
> walker to some other users. Core change comes from patch 1, so please
> see it for how it's supposed to work.
> 
> This patchset changes core code in mm/pagewalk.c at first in patch 1 and 2,
> and then updates all of current users to make the code cleaner in patch
> 3-9. Patch 10 changes the interface of hugetlb_entry(), I put it here to
> keep bisectability of the whole patchset. Patch 11 applies page table walker
> to a new user queue_pages_range().

Unfortunately this is very incompatible with pending changes in
fs/proc/task_mmu.c.  Especially Kirill's "mm, thp: change
pmd_trans_huge_lock() to return taken lock".

Stephen will be away for a couple more weeks so I'll get an mmotm
released and hopefully Thierry and Mark will scoop it up(?). 
Alternatively, http://git.cmpxchg.org/?p=linux-mmots.git;a=summary is
up to date.

Please take a look, decide what you think we should do?

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH 0/11] update page table walker

[Naoya Horiguchi]

On Tue, Oct 15, 2013 at 01:43:17PM -0700, Andrew Morton wrote:
> On Mon, 14 Oct 2013 13:36:59 -0400 Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> wrote:
> 
> > Page table walker is widely used when you want to traverse page table
> > tree and do some work for the entries (and pages pointed to by them.)
> > This is a common operation, and keep the code clean and maintainable
> > is important. Moreover this patchset introduces caller-specific walk
> > control function which is helpful for us to newly introduce page table
> > walker to some other users. Core change comes from patch 1, so please
> > see it for how it's supposed to work.
> > 
> > This patchset changes core code in mm/pagewalk.c at first in patch 1 and 2,
> > and then updates all of current users to make the code cleaner in patch
> > 3-9. Patch 10 changes the interface of hugetlb_entry(), I put it here to
> > keep bisectability of the whole patchset. Patch 11 applies page table walker
> > to a new user queue_pages_range().
> 
> Unfortunately this is very incompatible with pending changes in
> fs/proc/task_mmu.c.  Especially Kirill's "mm, thp: change
> pmd_trans_huge_lock() to return taken lock".

OK, I'll rebase onto mmots in the next post, maybe after waiting for
a few days on the chance that somebody make comments and feedbacks.

> 
> Stephen will be away for a couple more weeks so I'll get an mmotm
> released and hopefully Thierry and Mark will scoop it up(?). 
> Alternatively, http://git.cmpxchg.org/?p=linux-mmots.git;a=summary is
> up to date.
> 
> Please take a look, decide what you think we should do?

This patchset is ver.1, so I think that we need reviews before thinking
about merging. Please wait for my next post on top of this tree.

Thanks,
Naoya Horiguchi

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH 0/11] update page table walker

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 2164 bytes --]

On Tue, Oct 15, 2013 at 01:43:17PM -0700, Andrew Morton wrote:
> On Mon, 14 Oct 2013 13:36:59 -0400 Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> wrote:
> 
> > Page table walker is widely used when you want to traverse page table
> > tree and do some work for the entries (and pages pointed to by them.)
> > This is a common operation, and keep the code clean and maintainable
> > is important. Moreover this patchset introduces caller-specific walk
> > control function which is helpful for us to newly introduce page table
> > walker to some other users. Core change comes from patch 1, so please
> > see it for how it's supposed to work.
> > 
> > This patchset changes core code in mm/pagewalk.c at first in patch 1 and 2,
> > and then updates all of current users to make the code cleaner in patch
> > 3-9. Patch 10 changes the interface of hugetlb_entry(), I put it here to
> > keep bisectability of the whole patchset. Patch 11 applies page table walker
> > to a new user queue_pages_range().
> 
> Unfortunately this is very incompatible with pending changes in
> fs/proc/task_mmu.c.  Especially Kirill's "mm, thp: change
> pmd_trans_huge_lock() to return taken lock".
> 
> Stephen will be away for a couple more weeks so I'll get an mmotm
> released and hopefully Thierry and Mark will scoop it up(?). 
> Alternatively, http://git.cmpxchg.org/?p=linux-mmots.git;a=summary is
> up to date.
> 
> Please take a look, decide what you think we should do?

Hi Andrew,

I haven't had the time to look at writing up the scripts to import the
mmotm into the linux-next trees that I create. From what I understand,
it might be unwise to just pull linux-mmots into linux-next because it
isn't very well tested. Then again, increasing test coverage is one of
the goals of linux-next. If you think it's safe to include linux-mmots
in linux-next I can easily do that.

Otherwise I'll see if I can resume work on the scripts I started to
import the mmotm. Stephen has also provided the scripts that he used,
but I haven't had much time to look at them in detail yet because of
other things that have been keeping me busy.

Thierry

[-- Attachment #2: Type: application/pgp-signature, Size: 836 bytes --]

[PATCH 10/11] pagewalk: remove argument hmask from hugetlb_entry()

[Naoya Horiguchi]

hugetlb_entry() doesn't use the argument hmask any more,
so let's remove it now.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 fs/proc/task_mmu.c | 12 ++++++------
 include/linux/mm.h |  5 ++---
 mm/pagewalk.c      |  2 +-
 3 files changed, 9 insertions(+), 10 deletions(-)

diff --git v3.14-rc2.orig/fs/proc/task_mmu.c v3.14-rc2/fs/proc/task_mmu.c
index 8b23bbcc5e04..f819d0d4a0e8 100644
--- v3.14-rc2.orig/fs/proc/task_mmu.c
+++ v3.14-rc2/fs/proc/task_mmu.c
@@ -1022,8 +1022,7 @@ static void huge_pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *
 }
 
 /* This function walks within one hugetlb entry in the single call */
-static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
-				 unsigned long addr, unsigned long end,
+static int pagemap_hugetlb(pte_t *pte, unsigned long addr, unsigned long end,
 				 struct mm_walk *walk)
 {
 	struct pagemapread *pm = walk->private;
@@ -1031,6 +1030,7 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
 	int err = 0;
 	int flags2;
 	pagemap_entry_t pme;
+	unsigned long hmask;
 
 	WARN_ON_ONCE(!vma);
 
@@ -1292,8 +1292,8 @@ static int gather_pmd_stats(pmd_t *pmd, unsigned long addr,
 	return 0;
 }
 #ifdef CONFIG_HUGETLB_PAGE
-static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
-		unsigned long addr, unsigned long end, struct mm_walk *walk)
+static int gather_hugetlb_stats(pte_t *pte, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
 {
 	struct numa_maps *md;
 	struct page *page;
@@ -1311,8 +1311,8 @@ static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
 }
 
 #else
-static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
-		unsigned long addr, unsigned long end, struct mm_walk *walk)
+static int gather_hugetlb_stats(pte_t *pte, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
 {
 	return 0;
 }
diff --git v3.14-rc2.orig/include/linux/mm.h v3.14-rc2/include/linux/mm.h
index 144b08617957..7b6b596a5bf1 100644
--- v3.14-rc2.orig/include/linux/mm.h
+++ v3.14-rc2/include/linux/mm.h
@@ -1091,9 +1091,8 @@ struct mm_walk {
 			 unsigned long next, struct mm_walk *walk);
 	int (*pte_hole)(unsigned long addr, unsigned long next,
 			struct mm_walk *walk);
-	int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
-			     unsigned long addr, unsigned long next,
-			     struct mm_walk *walk);
+	int (*hugetlb_entry)(pte_t *pte, unsigned long addr,
+			unsigned long next, struct mm_walk *walk);
 	int (*test_walk)(unsigned long addr, unsigned long next,
 			struct mm_walk *walk);
 	struct mm_struct *mm;
diff --git v3.14-rc2.orig/mm/pagewalk.c v3.14-rc2/mm/pagewalk.c
index 2a88dfa58af6..416e981243b1 100644
--- v3.14-rc2.orig/mm/pagewalk.c
+++ v3.14-rc2/mm/pagewalk.c
@@ -199,7 +199,7 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
 		 * in walk->hugetlb_entry().
 		 */
 		if (pte && walk->hugetlb_entry)
-			err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
+			err = walk->hugetlb_entry(pte, addr, next, walk);
 		spin_unlock(ptl);
 		if (err)
 			break;
-- 
1.8.5.3

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 10/11] pagewalk: remove argument hmask from hugetlb_entry()

[Naoya Horiguchi]

hugetlb_entry() doesn't use the argument hmask any more,
so let's remove it now.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 fs/proc/task_mmu.c | 12 ++++++------
 include/linux/mm.h |  5 ++---
 mm/pagewalk.c      |  2 +-
 3 files changed, 9 insertions(+), 10 deletions(-)

diff --git mmotm-2014-01-09-16-23.orig/fs/proc/task_mmu.c mmotm-2014-01-09-16-23/fs/proc/task_mmu.c
index a1903e4b9514..80507c589d30 100644
--- mmotm-2014-01-09-16-23.orig/fs/proc/task_mmu.c
+++ mmotm-2014-01-09-16-23/fs/proc/task_mmu.c
@@ -1030,8 +1030,7 @@ static void huge_pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *
 }
 
 /* This function walks within one hugetlb entry in the single call */
-static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
-				 unsigned long addr, unsigned long end,
+static int pagemap_hugetlb(pte_t *pte, unsigned long addr, unsigned long end,
 				 struct mm_walk *walk)
 {
 	struct pagemapread *pm = walk->private;
@@ -1039,6 +1038,7 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
 	int err = 0;
 	int flags2;
 	pagemap_entry_t pme;
+	unsigned long hmask;
 
 	WARN_ON_ONCE(!vma);
 
@@ -1300,8 +1300,8 @@ static int gather_pmd_stats(pmd_t *pmd, unsigned long addr,
 	return 0;
 }
 #ifdef CONFIG_HUGETLB_PAGE
-static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
-		unsigned long addr, unsigned long end, struct mm_walk *walk)
+static int gather_hugetlb_stats(pte_t *pte, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
 {
 	struct numa_maps *md;
 	struct page *page;
@@ -1319,8 +1319,8 @@ static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
 }
 
 #else
-static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
-		unsigned long addr, unsigned long end, struct mm_walk *walk)
+static int gather_hugetlb_stats(pte_t *pte, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
 {
 	return 0;
 }
diff --git mmotm-2014-01-09-16-23.orig/include/linux/mm.h mmotm-2014-01-09-16-23/include/linux/mm.h
index 262e9d943533..0601ce59465a 100644
--- mmotm-2014-01-09-16-23.orig/include/linux/mm.h
+++ mmotm-2014-01-09-16-23/include/linux/mm.h
@@ -1008,9 +1008,8 @@ struct mm_walk {
 			 unsigned long next, struct mm_walk *walk);
 	int (*pte_hole)(unsigned long addr, unsigned long next,
 			struct mm_walk *walk);
-	int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
-			     unsigned long addr, unsigned long next,
-			     struct mm_walk *walk);
+	int (*hugetlb_entry)(pte_t *pte, unsigned long addr,
+			unsigned long next, struct mm_walk *walk);
 	int (*test_walk)(unsigned long addr, unsigned long next,
 			struct mm_walk *walk);
 	struct mm_struct *mm;
diff --git mmotm-2014-01-09-16-23.orig/mm/pagewalk.c mmotm-2014-01-09-16-23/mm/pagewalk.c
index 98a2385616a2..b639964c7b11 100644
--- mmotm-2014-01-09-16-23.orig/mm/pagewalk.c
+++ mmotm-2014-01-09-16-23/mm/pagewalk.c
@@ -198,7 +198,7 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
 		 * in walk->hugetlb_entry().
 		 */
 		if (pte && walk->hugetlb_entry)
-			err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
+			err = walk->hugetlb_entry(pte, addr, next, walk);
 		spin_unlock(ptl);
 		if (err)
 			break;
-- 
1.8.4.2

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 10/11] pagewalk: remove argument hmask from hugetlb_entry()

[Naoya Horiguchi]

hugetlb_entry() doesn't use the argument hmask any more,
so let's remove it now.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 fs/proc/task_mmu.c | 12 ++++++------
 include/linux/mm.h |  5 ++---
 mm/pagewalk.c      |  2 +-
 3 files changed, 9 insertions(+), 10 deletions(-)

diff --git v3.13-rc3-mmots-2013-12-10-16-38.orig/fs/proc/task_mmu.c v3.13-rc3-mmots-2013-12-10-16-38/fs/proc/task_mmu.c
index 8b23bbcc5e04..f819d0d4a0e8 100644
--- v3.13-rc3-mmots-2013-12-10-16-38.orig/fs/proc/task_mmu.c
+++ v3.13-rc3-mmots-2013-12-10-16-38/fs/proc/task_mmu.c
@@ -1022,8 +1022,7 @@ static void huge_pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *
 }
 
 /* This function walks within one hugetlb entry in the single call */
-static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
-				 unsigned long addr, unsigned long end,
+static int pagemap_hugetlb(pte_t *pte, unsigned long addr, unsigned long end,
 				 struct mm_walk *walk)
 {
 	struct pagemapread *pm = walk->private;
@@ -1031,6 +1030,7 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
 	int err = 0;
 	int flags2;
 	pagemap_entry_t pme;
+	unsigned long hmask;
 
 	WARN_ON_ONCE(!vma);
 
@@ -1292,8 +1292,8 @@ static int gather_pmd_stats(pmd_t *pmd, unsigned long addr,
 	return 0;
 }
 #ifdef CONFIG_HUGETLB_PAGE
-static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
-		unsigned long addr, unsigned long end, struct mm_walk *walk)
+static int gather_hugetlb_stats(pte_t *pte, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
 {
 	struct numa_maps *md;
 	struct page *page;
@@ -1311,8 +1311,8 @@ static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
 }
 
 #else
-static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
-		unsigned long addr, unsigned long end, struct mm_walk *walk)
+static int gather_hugetlb_stats(pte_t *pte, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
 {
 	return 0;
 }
diff --git v3.13-rc3-mmots-2013-12-10-16-38.orig/include/linux/mm.h v3.13-rc3-mmots-2013-12-10-16-38/include/linux/mm.h
index 8d1a3659419d..8008afa6dd64 100644
--- v3.13-rc3-mmots-2013-12-10-16-38.orig/include/linux/mm.h
+++ v3.13-rc3-mmots-2013-12-10-16-38/include/linux/mm.h
@@ -1088,9 +1088,8 @@ struct mm_walk {
 			 unsigned long next, struct mm_walk *walk);
 	int (*pte_hole)(unsigned long addr, unsigned long next,
 			struct mm_walk *walk);
-	int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
-			     unsigned long addr, unsigned long next,
-			     struct mm_walk *walk);
+	int (*hugetlb_entry)(pte_t *pte, unsigned long addr,
+			unsigned long next, struct mm_walk *walk);
 	int (*test_walk)(unsigned long addr, unsigned long next,
 			struct mm_walk *walk);
 	struct mm_struct *mm;
diff --git v3.13-rc3-mmots-2013-12-10-16-38.orig/mm/pagewalk.c v3.13-rc3-mmots-2013-12-10-16-38/mm/pagewalk.c
index f4ba2c212330..31333473c725 100644
--- v3.13-rc3-mmots-2013-12-10-16-38.orig/mm/pagewalk.c
+++ v3.13-rc3-mmots-2013-12-10-16-38/mm/pagewalk.c
@@ -189,7 +189,7 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
 		 * in walk->hugetlb_entry().
 		 */
 		if (pte && walk->hugetlb_entry)
-			err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
+			err = walk->hugetlb_entry(pte, addr, next, walk);
 		spin_unlock(ptl);
 		if (err)
 			break;
-- 
1.8.3.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 10/11] pagewalk: remove argument hmask from hugetlb_entry()

[Naoya Horiguchi]

All of callbacks connected to hugetlb_entry() are changed not to
use the argument hmask. So we can remove it now.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
 fs/proc/task_mmu.c | 12 ++++++------
 include/linux/mm.h |  5 ++---
 mm/pagewalk.c      |  2 +-
 3 files changed, 9 insertions(+), 10 deletions(-)

diff --git v3.12-rc7-mmots-2013-10-29-16-24.orig/fs/proc/task_mmu.c v3.12-rc7-mmots-2013-10-29-16-24/fs/proc/task_mmu.c
index 486737a..7c7f82b 100644
--- v3.12-rc7-mmots-2013-10-29-16-24.orig/fs/proc/task_mmu.c
+++ v3.12-rc7-mmots-2013-10-29-16-24/fs/proc/task_mmu.c
@@ -1043,8 +1043,7 @@ static void huge_pte_to_pagemap_entry(pagemap_entry_t *pme, struct pagemapread *
 }
 
 /* This function walks within one hugetlb entry in the single call */
-static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
-				 unsigned long addr, unsigned long end,
+static int pagemap_hugetlb(pte_t *pte, unsigned long addr, unsigned long end,
 				 struct mm_walk *walk)
 {
 	struct pagemapread *pm = walk->private;
@@ -1052,6 +1051,7 @@ static int pagemap_hugetlb_range(pte_t *pte, unsigned long hmask,
 	int err = 0;
 	int flags2;
 	pagemap_entry_t pme;
+	unsigned long hmask;
 
 	WARN_ON_ONCE(!vma);
 
@@ -1313,8 +1313,8 @@ static int gather_pmd_stats(pmd_t *pmd, unsigned long addr,
 	return 0;
 }
 #ifdef CONFIG_HUGETLB_PAGE
-static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
-		unsigned long addr, unsigned long end, struct mm_walk *walk)
+static int gather_hugetlb_stats(pte_t *pte, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
 {
 	struct numa_maps *md;
 	struct page *page;
@@ -1332,8 +1332,8 @@ static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
 }
 
 #else
-static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
-		unsigned long addr, unsigned long end, struct mm_walk *walk)
+static int gather_hugetlb_stats(pte_t *pte, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
 {
 	return 0;
 }
diff --git v3.12-rc7-mmots-2013-10-29-16-24.orig/include/linux/mm.h v3.12-rc7-mmots-2013-10-29-16-24/include/linux/mm.h
index f31f22f..35334e7 100644
--- v3.12-rc7-mmots-2013-10-29-16-24.orig/include/linux/mm.h
+++ v3.12-rc7-mmots-2013-10-29-16-24/include/linux/mm.h
@@ -1050,9 +1050,8 @@ struct mm_walk {
 			 unsigned long next, struct mm_walk *walk);
 	int (*pte_hole)(unsigned long addr, unsigned long next,
 			struct mm_walk *walk);
-	int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
-			     unsigned long addr, unsigned long next,
-			     struct mm_walk *walk);
+	int (*hugetlb_entry)(pte_t *pte, unsigned long addr,
+			unsigned long next, struct mm_walk *walk);
 	int (*test_walk)(unsigned long addr, unsigned long next,
 			struct mm_walk *walk);
 	struct mm_struct *mm;
diff --git v3.12-rc7-mmots-2013-10-29-16-24.orig/mm/pagewalk.c v3.12-rc7-mmots-2013-10-29-16-24/mm/pagewalk.c
index e837502..60bc4cf 100644
--- v3.12-rc7-mmots-2013-10-29-16-24.orig/mm/pagewalk.c
+++ v3.12-rc7-mmots-2013-10-29-16-24/mm/pagewalk.c
@@ -189,7 +189,7 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
 		 * in walk->hugetlb_entry().
 		 */
 		if (pte && walk->hugetlb_entry)
-			err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
+			err = walk->hugetlb_entry(pte, addr, next, walk);
 		spin_unlock(ptl);
 		if (err)
 			break;
-- 
1.8.3.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>