[v7,1/5] mm: introduce MADV_COLD
diff mbox series

Message ID 20190726023435.214162-2-minchan@kernel.org
State In Next
Commit c3e7d2071131e2d25ac265df8092ef59dfcd4a23
Headers show
Series
  • Introduce MADV_COLD and MADV_PAGEOUT
Related show

Commit Message

Minchan Kim July 26, 2019, 2:34 a.m. UTC
When a process expects no accesses to a certain memory range, it could
give a hint to kernel that the pages can be reclaimed when memory pressure
happens but data should be preserved for future use.  This could reduce
workingset eviction so it ends up increasing performance.

This patch introduces the new MADV_COLD hint to madvise(2) syscall.
MADV_COLD can be used by a process to mark a memory range as not expected
to be used in the near future. The hint can help kernel in deciding which
pages to evict early during memory pressure.

It works for every LRU pages like MADV_[DONTNEED|FREE]. IOW, It moves

	active file page -> inactive file LRU
	active anon page -> inacdtive anon LRU

Unlike MADV_FREE, it doesn't move active anonymous pages to inactive
file LRU's head because MADV_COLD is a little bit different symantic.
MADV_FREE means it's okay to discard when the memory pressure because
the content of the page is *garbage* so freeing such pages is almost zero
overhead since we don't need to swap out and access afterward causes just
minor fault. Thus, it would make sense to put those freeable pages in
inactive file LRU to compete other used-once pages. It makes sense for
implmentaion point of view, too because it's not swapbacked memory any
longer until it would be re-dirtied. Even, it could give a bonus to make
them be reclaimed on swapless system. However, MADV_COLD doesn't mean
garbage so reclaiming them requires swap-out/in in the end so it's bigger
cost. Since we have designed VM LRU aging based on cost-model, anonymous
cold pages would be better to position inactive anon's LRU list, not file
LRU. Furthermore, it would help to avoid unnecessary scanning if system
doesn't have a swap device. Let's start simpler way without adding
complexity at this moment. However, keep in mind, too that it's a caveat
that workloads with a lot of pages cache are likely to ignore MADV_COLD
on anonymous memory because we rarely age anonymous LRU lists.

* man-page material

MADV_COLD (since Linux x.x)

Pages in the specified regions will be treated as less-recently-accessed
compared to pages in the system with similar access frequencies.
In contrast to MADV_FREE, the contents of the region are preserved
regardless of subsequent writes to pages.

MADV_COLD cannot be applied to locked pages, Huge TLB pages, or VM_PFNMAP
pages.

* v6
 * Fix build error kbuildbot reported
   * https://lore.kernel.org/linux-mm/201907251647.fhJ6XzdA%25lkp@intel.com/
   * https://lore.kernel.org/linux-mm/201907251529.kTj2FpcL%25lkp@intel.com/

* v5
 * Fix typo and correct wrong lazy_mmu_mode pair use - surenb

* v2
 * add up the warn with lots of page cache workload - mhocko
 * add man page stuff - dave

* v1
 * remove page_mapcount filter - hannes, mhocko
 * remove idle page handling - joelaf

* RFCv2
 * add more description - mhocko

* RFCv1
 * renaming from MADV_COOL to MADV_COLD - hannes

* internal review
 * use clear_page_youn in deactivate_page - joelaf
 * Revise the description - surenb
 * Renaming from MADV_WARM to MADV_COOL - surenb

Cc: linux-arch@vger.kernel.org
Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Chris Zankel <chris@zankel.net>
Reported-by: kbuild test robot <lkp@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 arch/alpha/include/uapi/asm/mman.h     |   2 +
 arch/mips/include/uapi/asm/mman.h      |   2 +
 arch/parisc/include/uapi/asm/mman.h    |   2 +
 arch/xtensa/include/uapi/asm/mman.h    |   2 +
 include/linux/swap.h                   |   1 +
 include/uapi/asm-generic/mman-common.h |   2 +
 mm/internal.h                          |   2 +-
 mm/madvise.c                           | 181 ++++++++++++++++++++++++-
 mm/oom_kill.c                          |   2 +-
 mm/swap.c                              |  42 ++++++
 10 files changed, 234 insertions(+), 4 deletions(-)

Patch
diff mbox series

diff --git a/arch/alpha/include/uapi/asm/mman.h b/arch/alpha/include/uapi/asm/mman.h
index ac23379b7a876..f3258fbf03d03 100644
--- a/arch/alpha/include/uapi/asm/mman.h
+++ b/arch/alpha/include/uapi/asm/mman.h
@@ -68,6 +68,8 @@ 
 #define MADV_WIPEONFORK 18		/* Zero memory on fork, child only */
 #define MADV_KEEPONFORK 19		/* Undo MADV_WIPEONFORK */
 
+#define MADV_COLD	20		/* deactivate these pages */
+
 /* compatibility flags */
 #define MAP_FILE	0
 
diff --git a/arch/mips/include/uapi/asm/mman.h b/arch/mips/include/uapi/asm/mman.h
index c2b40969eb1fa..00ad09fc5eb16 100644
--- a/arch/mips/include/uapi/asm/mman.h
+++ b/arch/mips/include/uapi/asm/mman.h
@@ -95,6 +95,8 @@ 
 #define MADV_WIPEONFORK 18		/* Zero memory on fork, child only */
 #define MADV_KEEPONFORK 19		/* Undo MADV_WIPEONFORK */
 
+#define MADV_COLD	20		/* deactivate these pages */
+
 /* compatibility flags */
 #define MAP_FILE	0
 
diff --git a/arch/parisc/include/uapi/asm/mman.h b/arch/parisc/include/uapi/asm/mman.h
index c98162f494dbb..eb14e3a7b8f37 100644
--- a/arch/parisc/include/uapi/asm/mman.h
+++ b/arch/parisc/include/uapi/asm/mman.h
@@ -48,6 +48,8 @@ 
 #define MADV_DONTFORK	10		/* don't inherit across fork */
 #define MADV_DOFORK	11		/* do inherit across fork */
 
+#define MADV_COLD	20		/* deactivate these pages */
+
 #define MADV_MERGEABLE   65		/* KSM may merge identical pages */
 #define MADV_UNMERGEABLE 66		/* KSM may not merge identical pages */
 
diff --git a/arch/xtensa/include/uapi/asm/mman.h b/arch/xtensa/include/uapi/asm/mman.h
index ebbb48842190d..f926b00ff11f9 100644
--- a/arch/xtensa/include/uapi/asm/mman.h
+++ b/arch/xtensa/include/uapi/asm/mman.h
@@ -103,6 +103,8 @@ 
 #define MADV_WIPEONFORK 18		/* Zero memory on fork, child only */
 #define MADV_KEEPONFORK 19		/* Undo MADV_WIPEONFORK */
 
+#define MADV_COLD	20		/* deactivate these pages */
+
 /* compatibility flags */
 #define MAP_FILE	0
 
diff --git a/include/linux/swap.h b/include/linux/swap.h
index de2c67a33b7e7..0ce997edb8bbc 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -340,6 +340,7 @@  extern void lru_add_drain_cpu(int cpu);
 extern void lru_add_drain_all(void);
 extern void rotate_reclaimable_page(struct page *page);
 extern void deactivate_file_page(struct page *page);
+extern void deactivate_page(struct page *page);
 extern void mark_page_lazyfree(struct page *page);
 extern void swap_setup(void);
 
diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
index 63b1f506ea678..23431faf0eb6e 100644
--- a/include/uapi/asm-generic/mman-common.h
+++ b/include/uapi/asm-generic/mman-common.h
@@ -67,6 +67,8 @@ 
 #define MADV_WIPEONFORK 18		/* Zero memory on fork, child only */
 #define MADV_KEEPONFORK 19		/* Undo MADV_WIPEONFORK */
 
+#define MADV_COLD	20		/* deactivate these pages */
+
 /* compatibility flags */
 #define MAP_FILE	0
 
diff --git a/mm/internal.h b/mm/internal.h
index e32390802fd3f..0d5f720c75abf 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -39,7 +39,7 @@  vm_fault_t do_swap_page(struct vm_fault *vmf);
 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
 		unsigned long floor, unsigned long ceiling);
 
-static inline bool can_madv_dontneed_vma(struct vm_area_struct *vma)
+static inline bool can_madv_lru_vma(struct vm_area_struct *vma)
 {
 	return !(vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP));
 }
diff --git a/mm/madvise.c b/mm/madvise.c
index 968df3aa069fd..e724bce09d7ca 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -11,6 +11,7 @@ 
 #include <linux/syscalls.h>
 #include <linux/mempolicy.h>
 #include <linux/page-isolation.h>
+#include <linux/page_idle.h>
 #include <linux/userfaultfd_k.h>
 #include <linux/hugetlb.h>
 #include <linux/falloc.h>
@@ -40,6 +41,7 @@  static int madvise_need_mmap_write(int behavior)
 	case MADV_REMOVE:
 	case MADV_WILLNEED:
 	case MADV_DONTNEED:
+	case MADV_COLD:
 	case MADV_FREE:
 		return 0;
 	default:
@@ -307,6 +309,178 @@  static long madvise_willneed(struct vm_area_struct *vma,
 	return 0;
 }
 
+static int madvise_cold_pte_range(pmd_t *pmd, unsigned long addr,
+				unsigned long end, struct mm_walk *walk)
+{
+	struct mmu_gather *tlb = walk->private;
+	struct mm_struct *mm = tlb->mm;
+	struct vm_area_struct *vma = walk->vma;
+	pte_t *orig_pte, *pte, ptent;
+	spinlock_t *ptl;
+	struct page *page;
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	if (pmd_trans_huge(*pmd)) {
+		pmd_t orig_pmd;
+		unsigned long next = pmd_addr_end(addr, end);
+
+		tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
+		ptl = pmd_trans_huge_lock(pmd, vma);
+		if (!ptl)
+			return 0;
+
+		orig_pmd = *pmd;
+		if (is_huge_zero_pmd(orig_pmd))
+			goto huge_unlock;
+
+		if (unlikely(!pmd_present(orig_pmd))) {
+			VM_BUG_ON(thp_migration_supported() &&
+					!is_pmd_migration_entry(orig_pmd));
+			goto huge_unlock;
+		}
+
+		page = pmd_page(orig_pmd);
+		if (next - addr != HPAGE_PMD_SIZE) {
+			int err;
+
+			if (page_mapcount(page) != 1)
+				goto huge_unlock;
+
+			get_page(page);
+			spin_unlock(ptl);
+			lock_page(page);
+			err = split_huge_page(page);
+			unlock_page(page);
+			put_page(page);
+			if (!err)
+				goto regular_page;
+			return 0;
+		}
+
+		if (pmd_young(orig_pmd)) {
+			pmdp_invalidate(vma, addr, pmd);
+			orig_pmd = pmd_mkold(orig_pmd);
+
+			set_pmd_at(mm, addr, pmd, orig_pmd);
+			tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
+		}
+
+		test_and_clear_page_young(page);
+		deactivate_page(page);
+huge_unlock:
+		spin_unlock(ptl);
+		return 0;
+	}
+
+	if (pmd_trans_unstable(pmd))
+		return 0;
+regular_page:
+#endif
+	tlb_change_page_size(tlb, PAGE_SIZE);
+	orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	flush_tlb_batched_pending(mm);
+	arch_enter_lazy_mmu_mode();
+	for (; addr < end; pte++, addr += PAGE_SIZE) {
+		ptent = *pte;
+
+		if (pte_none(ptent))
+			continue;
+
+		if (!pte_present(ptent))
+			continue;
+
+		page = vm_normal_page(vma, addr, ptent);
+		if (!page)
+			continue;
+
+		/*
+		 * Creating a THP page is expensive so split it only if we
+		 * are sure it's worth. Split it if we are only owner.
+		 */
+		if (PageTransCompound(page)) {
+			if (page_mapcount(page) != 1)
+				break;
+			get_page(page);
+			if (!trylock_page(page)) {
+				put_page(page);
+				break;
+			}
+			pte_unmap_unlock(orig_pte, ptl);
+			if (split_huge_page(page)) {
+				unlock_page(page);
+				put_page(page);
+				pte_offset_map_lock(mm, pmd, addr, &ptl);
+				break;
+			}
+			unlock_page(page);
+			put_page(page);
+			pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
+			pte--;
+			addr -= PAGE_SIZE;
+			continue;
+		}
+
+		VM_BUG_ON_PAGE(PageTransCompound(page), page);
+
+		if (pte_young(ptent)) {
+			ptent = ptep_get_and_clear_full(mm, addr, pte,
+							tlb->fullmm);
+			ptent = pte_mkold(ptent);
+			set_pte_at(mm, addr, pte, ptent);
+			tlb_remove_tlb_entry(tlb, pte, addr);
+		}
+
+		/*
+		 * We are deactivating a page for accelerating reclaiming.
+		 * VM couldn't reclaim the page unless we clear PG_young.
+		 * As a side effect, it makes confuse idle-page tracking
+		 * because they will miss recent referenced history.
+		 */
+		test_and_clear_page_young(page);
+		deactivate_page(page);
+	}
+
+	arch_leave_lazy_mmu_mode();
+	pte_unmap_unlock(orig_pte, ptl);
+	cond_resched();
+
+	return 0;
+}
+
+static void madvise_cold_page_range(struct mmu_gather *tlb,
+			     struct vm_area_struct *vma,
+			     unsigned long addr, unsigned long end)
+{
+	struct mm_walk cold_walk = {
+		.pmd_entry = madvise_cold_pte_range,
+		.mm = vma->vm_mm,
+		.private = tlb,
+	};
+
+	tlb_start_vma(tlb, vma);
+	walk_page_range(addr, end, &cold_walk);
+	tlb_end_vma(tlb, vma);
+}
+
+static long madvise_cold(struct vm_area_struct *vma,
+			struct vm_area_struct **prev,
+			unsigned long start_addr, unsigned long end_addr)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	struct mmu_gather tlb;
+
+	*prev = vma;
+	if (!can_madv_lru_vma(vma))
+		return -EINVAL;
+
+	lru_add_drain();
+	tlb_gather_mmu(&tlb, mm, start_addr, end_addr);
+	madvise_cold_page_range(&tlb, vma, start_addr, end_addr);
+	tlb_finish_mmu(&tlb, start_addr, end_addr);
+
+	return 0;
+}
+
 static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 				unsigned long end, struct mm_walk *walk)
 
@@ -519,7 +693,7 @@  static long madvise_dontneed_free(struct vm_area_struct *vma,
 				  int behavior)
 {
 	*prev = vma;
-	if (!can_madv_dontneed_vma(vma))
+	if (!can_madv_lru_vma(vma))
 		return -EINVAL;
 
 	if (!userfaultfd_remove(vma, start, end)) {
@@ -541,7 +715,7 @@  static long madvise_dontneed_free(struct vm_area_struct *vma,
 			 */
 			return -ENOMEM;
 		}
-		if (!can_madv_dontneed_vma(vma))
+		if (!can_madv_lru_vma(vma))
 			return -EINVAL;
 		if (end > vma->vm_end) {
 			/*
@@ -695,6 +869,8 @@  madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
 		return madvise_remove(vma, prev, start, end);
 	case MADV_WILLNEED:
 		return madvise_willneed(vma, prev, start, end);
+	case MADV_COLD:
+		return madvise_cold(vma, prev, start, end);
 	case MADV_FREE:
 	case MADV_DONTNEED:
 		return madvise_dontneed_free(vma, prev, start, end, behavior);
@@ -716,6 +892,7 @@  madvise_behavior_valid(int behavior)
 	case MADV_WILLNEED:
 	case MADV_DONTNEED:
 	case MADV_FREE:
+	case MADV_COLD:
 #ifdef CONFIG_KSM
 	case MADV_MERGEABLE:
 	case MADV_UNMERGEABLE:
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index a2a5edbf61789..493028ad865f1 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -522,7 +522,7 @@  bool __oom_reap_task_mm(struct mm_struct *mm)
 	set_bit(MMF_UNSTABLE, &mm->flags);
 
 	for (vma = mm->mmap ; vma; vma = vma->vm_next) {
-		if (!can_madv_dontneed_vma(vma))
+		if (!can_madv_lru_vma(vma))
 			continue;
 
 		/*
diff --git a/mm/swap.c b/mm/swap.c
index 0226c53465604..9c0c5d6286faa 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -47,6 +47,7 @@  int page_cluster;
 static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
 static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
 static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs);
+static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
 static DEFINE_PER_CPU(struct pagevec, lru_lazyfree_pvecs);
 #ifdef CONFIG_SMP
 static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
@@ -538,6 +539,22 @@  static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
 	update_page_reclaim_stat(lruvec, file, 0);
 }
 
+static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
+			    void *arg)
+{
+	if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
+		int file = page_is_file_cache(page);
+		int lru = page_lru_base_type(page);
+
+		del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE);
+		ClearPageActive(page);
+		ClearPageReferenced(page);
+		add_page_to_lru_list(page, lruvec, lru);
+
+		__count_vm_events(PGDEACTIVATE, hpage_nr_pages(page));
+		update_page_reclaim_stat(lruvec, file, 0);
+	}
+}
 
 static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec,
 			    void *arg)
@@ -590,6 +607,10 @@  void lru_add_drain_cpu(int cpu)
 	if (pagevec_count(pvec))
 		pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
 
+	pvec = &per_cpu(lru_deactivate_pvecs, cpu);
+	if (pagevec_count(pvec))
+		pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
+
 	pvec = &per_cpu(lru_lazyfree_pvecs, cpu);
 	if (pagevec_count(pvec))
 		pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL);
@@ -623,6 +644,26 @@  void deactivate_file_page(struct page *page)
 	}
 }
 
+/*
+ * deactivate_page - deactivate a page
+ * @page: page to deactivate
+ *
+ * deactivate_page() moves @page to the inactive list if @page was on the active
+ * list and was not an unevictable page.  This is done to accelerate the reclaim
+ * of @page.
+ */
+void deactivate_page(struct page *page)
+{
+	if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
+		struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
+
+		get_page(page);
+		if (!pagevec_add(pvec, page) || PageCompound(page))
+			pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
+		put_cpu_var(lru_deactivate_pvecs);
+	}
+}
+
 /**
  * mark_page_lazyfree - make an anon page lazyfree
  * @page: page to deactivate
@@ -687,6 +728,7 @@  void lru_add_drain_all(void)
 		if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
 		    pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
 		    pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) ||
+		    pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) ||
 		    pagevec_count(&per_cpu(lru_lazyfree_pvecs, cpu)) ||
 		    need_activate_page_drain(cpu)) {
 			INIT_WORK(work, lru_add_drain_per_cpu);