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Date: Fri, 19 Sep 2014 15:17:34 +0900
From: Minchan Kim <minchan@...nel.org>
To: SeongJae Park <sj38.park@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
linux-mm@...ck.org, Michael Kerrisk <mtk.manpages@...il.com>,
linux-api@...r.kernel.org, Hugh Dickins <hughd@...gle.com>,
Johannes Weiner <hannes@...xchg.org>,
Rik van Riel <riel@...hat.com>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Mel Gorman <mgorman@...e.de>, Jason Evans <je@...com>,
Zhang Yanfei <zhangyanfei@...fujitsu.com>,
"Kirill A. Shutemov" <kirill@...temov.name>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCH v16 1/7] mm: support madvise(MADV_FREE)
Hi SeongJae,
On Tue, Sep 16, 2014 at 03:08:06PM +0900, SeongJae Park wrote:
> Hi Minchan,
>
> On Mon, Sep 1, 2014 at 4:20 PM, Minchan Kim <minchan@...nel.org> wrote:
> > Linux doesn't have an ability to free pages lazy while other OS
> > already have been supported that named by madvise(MADV_FREE).
> >
> > The gain is clear that kernel can discard freed pages rather than
> > swapping out or OOM if memory pressure happens.
> >
> > Without memory pressure, freed pages would be reused by userspace
> > without another additional overhead(ex, page fault + allocation
> > + zeroing).
> >
> > How to work is following as.
> >
> > When madvise syscall is called, VM clears dirty bit of ptes of
> > the range. If memory pressure happens, VM checks dirty bit of
> > page table and if it found still "clean", it means it's a
> > "lazyfree pages" so VM could discard the page instead of swapping out.
> > Once there was store operation for the page before VM peek a page
> > to reclaim, dirty bit is set so VM can swap out the page instead of
> > discarding.
> >
> > Firstly, heavy users would be general allocators(ex, jemalloc,
> > tcmalloc and hope glibc supports it) and jemalloc/tcmalloc already
> > have supported the feature for other OS(ex, FreeBSD)
> >
> > barrios@...ptop:~/benchmark/ebizzy$ lscpu
> > Architecture: x86_64
> > CPU op-mode(s): 32-bit, 64-bit
> > Byte Order: Little Endian
> > CPU(s): 4
> > On-line CPU(s) list: 0-3
> > Thread(s) per core: 2
> > Core(s) per socket: 2
> > Socket(s): 1
> > NUMA node(s): 1
> > Vendor ID: GenuineIntel
> > CPU family: 6
> > Model: 42
> > Stepping: 7
> > CPU MHz: 2801.000
> > BogoMIPS: 5581.64
> > Virtualization: VT-x
> > L1d cache: 32K
> > L1i cache: 32K
> > L2 cache: 256K
> > L3 cache: 4096K
> > NUMA node0 CPU(s): 0-3
> >
> > ebizzy benchmark(./ebizzy -S 10 -n 512)
> >
> > vanilla-jemalloc MADV_free-jemalloc
> >
> > 1 thread
> > records: 10 records: 10
> > avg: 7682.10 avg: 15306.10
> > std: 62.35(0.81%) std: 347.99(2.27%)
> > max: 7770.00 max: 15622.00
> > min: 7598.00 min: 14772.00
> >
> > 2 thread
> > records: 10 records: 10
> > avg: 12747.50 avg: 24171.00
> > std: 792.06(6.21%) std: 895.18(3.70%)
> > max: 13337.00 max: 26023.00
> > min: 10535.00 min: 23152.00
> >
> > 4 thread
> > records: 10 records: 10
> > avg: 16474.60 avg: 33717.90
> > std: 1496.45(9.08%) std: 2008.97(5.96%)
> > max: 17877.00 max: 35958.00
> > min: 12224.00 min: 29565.00
> >
> > 8 thread
> > records: 10 records: 10
> > avg: 16778.50 avg: 33308.10
> > std: 825.53(4.92%) std: 1668.30(5.01%)
> > max: 17543.00 max: 36010.00
> > min: 14576.00 min: 29577.00
> >
> > 16 thread
> > records: 10 records: 10
> > avg: 20614.40 avg: 35516.30
> > std: 602.95(2.92%) std: 1283.65(3.61%)
> > max: 21753.00 max: 37178.00
> > min: 19605.00 min: 33217.00
> >
> > 32 thread
> > records: 10 records: 10
> > avg: 22771.70 avg: 36018.50
> > std: 598.94(2.63%) std: 1046.76(2.91%)
> > max: 24035.00 max: 37266.00
> > min: 22108.00 min: 34149.00
> >
> > In summary, MADV_FREE is about 2 time faster than MADV_DONTNEED.
> >
> > Cc: Michael Kerrisk <mtk.manpages@...il.com>
> > Cc: Linux API <linux-api@...r.kernel.org>
> > Cc: Hugh Dickins <hughd@...gle.com>
> > Cc: Johannes Weiner <hannes@...xchg.org>
> > Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> > Cc: Mel Gorman <mgorman@...e.de>
> > Cc: Jason Evans <je@...com>
> > Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> > Acked-by: Zhang Yanfei <zhangyanfei@...fujitsu.com>
> > Acked-by: Rik van Riel <riel@...hat.com>
> > Signed-off-by: Minchan Kim <minchan@...nel.org>
> > ---
> > include/linux/rmap.h | 9 ++-
> > include/linux/vm_event_item.h | 1 +
> > include/uapi/asm-generic/mman-common.h | 1 +
> > mm/madvise.c | 140 +++++++++++++++++++++++++++++++++
> > mm/rmap.c | 42 +++++++++-
> > mm/vmscan.c | 40 ++++++++--
> > mm/vmstat.c | 1 +
> > 7 files changed, 222 insertions(+), 12 deletions(-)
> >
> > diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> > index c0c2bce6b0b7..14ec4ece14a5 100644
> > --- a/include/linux/rmap.h
> > +++ b/include/linux/rmap.h
> > @@ -75,6 +75,7 @@ enum ttu_flags {
> > TTU_UNMAP = 1, /* unmap mode */
> > TTU_MIGRATION = 2, /* migration mode */
> > TTU_MUNLOCK = 4, /* munlock mode */
> > + TTU_FREE = 8, /* free mode */
> >
> > TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */
> > TTU_IGNORE_ACCESS = (1 << 9), /* don't age */
> > @@ -181,7 +182,8 @@ static inline void page_dup_rmap(struct page *page)
> > * Called from mm/vmscan.c to handle paging out
> > */
> > int page_referenced(struct page *, int is_locked,
> > - struct mem_cgroup *memcg, unsigned long *vm_flags);
> > + struct mem_cgroup *memcg, unsigned long *vm_flags,
> > + int *is_dirty);
>
> Name of the last parameter is `is_dirty` here and `is_pte_dirty` in
> definition. Wouldn't it be better to use same name?
>
> I think this is just a really trivial question but, couldn't ignored.
I can fix/resend but Andrew is silent for a long time so I will wait
his opinion before meaningless resending.
>
> Thanks,
> SeongJae Park
>
> >
> > #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
> >
> > @@ -260,9 +262,12 @@ int rmap_walk(struct page *page, struct rmap_walk_control *rwc);
> >
> > static inline int page_referenced(struct page *page, int is_locked,
> > struct mem_cgroup *memcg,
> > - unsigned long *vm_flags)
> > + unsigned long *vm_flags,
> > + int *is_pte_dirty)
> > {
> > *vm_flags = 0;
> > + if (is_pte_dirty)
> > + *is_pte_dirty = 0;
> > return 0;
> > }
> >
> > diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
> > index ced92345c963..e2d3fb1e9814 100644
> > --- a/include/linux/vm_event_item.h
> > +++ b/include/linux/vm_event_item.h
> > @@ -25,6 +25,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
> > FOR_ALL_ZONES(PGALLOC),
> > PGFREE, PGACTIVATE, PGDEACTIVATE,
> > PGFAULT, PGMAJFAULT,
> > + PGLAZYFREED,
> > FOR_ALL_ZONES(PGREFILL),
> > FOR_ALL_ZONES(PGSTEAL_KSWAPD),
> > FOR_ALL_ZONES(PGSTEAL_DIRECT),
> > diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
> > index ddc3b36f1046..7a94102b7a02 100644
> > --- a/include/uapi/asm-generic/mman-common.h
> > +++ b/include/uapi/asm-generic/mman-common.h
> > @@ -34,6 +34,7 @@
> > #define MADV_SEQUENTIAL 2 /* expect sequential page references */
> > #define MADV_WILLNEED 3 /* will need these pages */
> > #define MADV_DONTNEED 4 /* don't need these pages */
> > +#define MADV_FREE 5 /* free pages only if memory pressure */
> >
> > /* common parameters: try to keep these consistent across architectures */
> > #define MADV_REMOVE 9 /* remove these pages & resources */
> > diff --git a/mm/madvise.c b/mm/madvise.c
> > index 0938b30da4ab..a21584235bb6 100644
> > --- a/mm/madvise.c
> > +++ b/mm/madvise.c
> > @@ -19,6 +19,14 @@
> > #include <linux/blkdev.h>
> > #include <linux/swap.h>
> > #include <linux/swapops.h>
> > +#include <linux/mmu_notifier.h>
> > +
> > +#include <asm/tlb.h>
> > +
> > +struct madvise_free_private {
> > + struct vm_area_struct *vma;
> > + struct mmu_gather *tlb;
> > +};
> >
> > /*
> > * Any behaviour which results in changes to the vma->vm_flags needs to
> > @@ -31,6 +39,7 @@ static int madvise_need_mmap_write(int behavior)
> > case MADV_REMOVE:
> > case MADV_WILLNEED:
> > case MADV_DONTNEED:
> > + case MADV_FREE:
> > return 0;
> > default:
> > /* be safe, default to 1. list exceptions explicitly */
> > @@ -251,6 +260,128 @@ static long madvise_willneed(struct vm_area_struct *vma,
> > return 0;
> > }
> >
> > +static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
> > + unsigned long end, struct mm_walk *walk)
> > +
> > +{
> > + struct madvise_free_private *fp = walk->private;
> > + struct mmu_gather *tlb = fp->tlb;
> > + struct mm_struct *mm = tlb->mm;
> > + struct vm_area_struct *vma = fp->vma;
> > + spinlock_t *ptl;
> > + pte_t *pte, ptent;
> > + struct page *page;
> > +
> > + split_huge_page_pmd(vma, addr, pmd);
> > + if (pmd_trans_unstable(pmd))
> > + return 0;
> > +
> > + pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
> > + arch_enter_lazy_mmu_mode();
> > + for (; addr != end; pte++, addr += PAGE_SIZE) {
> > + ptent = *pte;
> > +
> > + if (!pte_present(ptent))
> > + continue;
> > +
> > + page = vm_normal_page(vma, addr, ptent);
> > + if (!page)
> > + continue;
> > +
> > + if (PageSwapCache(page)) {
> > + if (!trylock_page(page))
> > + continue;
> > +
> > + if (!try_to_free_swap(page)) {
> > + unlock_page(page);
> > + continue;
> > + }
> > +
> > + ClearPageDirty(page);
> > + unlock_page(page);
> > + }
> > +
> > + /*
> > + * Some of architecture(ex, PPC) don't update TLB
> > + * with set_pte_at and tlb_remove_tlb_entry so for
> > + * the portability, remap the pte with old|clean
> > + * after pte clearing.
> > + */
> > + ptent = ptep_get_and_clear_full(mm, addr, pte,
> > + tlb->fullmm);
> > + ptent = pte_mkold(ptent);
> > + ptent = pte_mkclean(ptent);
> > + set_pte_at(mm, addr, pte, ptent);
> > + tlb_remove_tlb_entry(tlb, pte, addr);
> > + }
> > + arch_leave_lazy_mmu_mode();
> > + pte_unmap_unlock(pte - 1, ptl);
> > + cond_resched();
> > + return 0;
> > +}
> > +
> > +static void madvise_free_page_range(struct mmu_gather *tlb,
> > + struct vm_area_struct *vma,
> > + unsigned long addr, unsigned long end)
> > +{
> > + struct madvise_free_private fp = {
> > + .vma = vma,
> > + .tlb = tlb,
> > + };
> > +
> > + struct mm_walk free_walk = {
> > + .pmd_entry = madvise_free_pte_range,
> > + .mm = vma->vm_mm,
> > + .private = &fp,
> > + };
> > +
> > + BUG_ON(addr >= end);
> > + tlb_start_vma(tlb, vma);
> > + walk_page_range(addr, end, &free_walk);
> > + tlb_end_vma(tlb, vma);
> > +}
> > +
> > +static int madvise_free_single_vma(struct vm_area_struct *vma,
> > + unsigned long start_addr, unsigned long end_addr)
> > +{
> > + unsigned long start, end;
> > + struct mm_struct *mm = vma->vm_mm;
> > + struct mmu_gather tlb;
> > +
> > + if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
> > + return -EINVAL;
> > +
> > + /* MADV_FREE works for only anon vma at the moment */
> > + if (vma->vm_file)
> > + return -EINVAL;
> > +
> > + start = max(vma->vm_start, start_addr);
> > + if (start >= vma->vm_end)
> > + return -EINVAL;
> > + end = min(vma->vm_end, end_addr);
> > + if (end <= vma->vm_start)
> > + return -EINVAL;
> > +
> > + lru_add_drain();
> > + tlb_gather_mmu(&tlb, mm, start, end);
> > + update_hiwater_rss(mm);
> > +
> > + mmu_notifier_invalidate_range_start(mm, start, end);
> > + madvise_free_page_range(&tlb, vma, start, end);
> > + mmu_notifier_invalidate_range_end(mm, start, end);
> > + tlb_finish_mmu(&tlb, start, end);
> > +
> > + return 0;
> > +}
> > +
> > +static long madvise_free(struct vm_area_struct *vma,
> > + struct vm_area_struct **prev,
> > + unsigned long start, unsigned long end)
> > +{
> > + *prev = vma;
> > + return madvise_free_single_vma(vma, start, end);
> > +}
> > +
> > /*
> > * Application no longer needs these pages. If the pages are dirty,
> > * it's OK to just throw them away. The app will be more careful about
> > @@ -381,6 +512,14 @@ 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_FREE:
> > + /*
> > + * XXX: In this implementation, MADV_FREE works like
> > + * MADV_DONTNEED on swapless system or full swap.
> > + */
> > + if (get_nr_swap_pages() > 0)
> > + return madvise_free(vma, prev, start, end);
> > + /* passthrough */
> > case MADV_DONTNEED:
> > return madvise_dontneed(vma, prev, start, end);
> > default:
> > @@ -400,6 +539,7 @@ madvise_behavior_valid(int behavior)
> > case MADV_REMOVE:
> > case MADV_WILLNEED:
> > case MADV_DONTNEED:
> > + case MADV_FREE:
> > #ifdef CONFIG_KSM
> > case MADV_MERGEABLE:
> > case MADV_UNMERGEABLE:
> > diff --git a/mm/rmap.c b/mm/rmap.c
> > index 5fbd0fe8f933..93149c82a5a4 100644
> > --- a/mm/rmap.c
> > +++ b/mm/rmap.c
> > @@ -663,6 +663,7 @@ int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
> > }
> >
> > struct page_referenced_arg {
> > + int dirtied;
> > int mapcount;
> > int referenced;
> > unsigned long vm_flags;
> > @@ -677,6 +678,7 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
> > struct mm_struct *mm = vma->vm_mm;
> > spinlock_t *ptl;
> > int referenced = 0;
> > + int dirty = 0;
> > struct page_referenced_arg *pra = arg;
> >
> > if (unlikely(PageTransHuge(page))) {
> > @@ -700,6 +702,11 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
> > /* go ahead even if the pmd is pmd_trans_splitting() */
> > if (pmdp_clear_flush_young_notify(vma, address, pmd))
> > referenced++;
> > +
> > + /*
> > + * In this implmentation, MADV_FREE doesn't support THP free
> > + */
> > + dirty++;
> > spin_unlock(ptl);
> > } else {
> > pte_t *pte;
> > @@ -729,6 +736,10 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
> > if (likely(!(vma->vm_flags & VM_SEQ_READ)))
> > referenced++;
> > }
> > +
> > + if (pte_dirty(*pte))
> > + dirty++;
> > +
> > pte_unmap_unlock(pte, ptl);
> > }
> >
> > @@ -737,6 +748,9 @@ static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
> > pra->vm_flags |= vma->vm_flags;
> > }
> >
> > + if (dirty)
> > + pra->dirtied++;
> > +
> > pra->mapcount--;
> > if (!pra->mapcount)
> > return SWAP_SUCCESS; /* To break the loop */
> > @@ -761,6 +775,7 @@ static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg)
> > * @is_locked: caller holds lock on the page
> > * @memcg: target memory cgroup
> > * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
> > + * @is_pte_dirty: ptes which have marked dirty bit - used for lazyfree page
> > *
> > * Quick test_and_clear_referenced for all mappings to a page,
> > * returns the number of ptes which referenced the page.
> > @@ -768,7 +783,8 @@ static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg)
> > int page_referenced(struct page *page,
> > int is_locked,
> > struct mem_cgroup *memcg,
> > - unsigned long *vm_flags)
> > + unsigned long *vm_flags,
> > + int *is_pte_dirty)
> > {
> > int ret;
> > int we_locked = 0;
> > @@ -783,6 +799,9 @@ int page_referenced(struct page *page,
> > };
> >
> > *vm_flags = 0;
> > + if (is_pte_dirty)
> > + *is_pte_dirty = 0;
> > +
> > if (!page_mapped(page))
> > return 0;
> >
> > @@ -810,6 +829,9 @@ int page_referenced(struct page *page,
> > if (we_locked)
> > unlock_page(page);
> >
> > + if (is_pte_dirty)
> > + *is_pte_dirty = pra.dirtied;
> > +
> > return pra.referenced;
> > }
> >
> > @@ -1128,6 +1150,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
> > spinlock_t *ptl;
> > int ret = SWAP_AGAIN;
> > enum ttu_flags flags = (enum ttu_flags)arg;
> > + int dirty = 0;
> >
> > pte = page_check_address(page, mm, address, &ptl, 0);
> > if (!pte)
> > @@ -1157,7 +1180,8 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
> > pteval = ptep_clear_flush(vma, address, pte);
> >
> > /* Move the dirty bit to the physical page now the pte is gone. */
> > - if (pte_dirty(pteval))
> > + dirty = pte_dirty(pteval);
> > + if (dirty)
> > set_page_dirty(page);
> >
> > /* Update high watermark before we lower rss */
> > @@ -1186,6 +1210,19 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
> > swp_entry_t entry = { .val = page_private(page) };
> > pte_t swp_pte;
> >
> > + if (flags & TTU_FREE) {
> > + VM_BUG_ON_PAGE(PageSwapCache(page), page);
> > + if (!dirty && !PageDirty(page)) {
> > + /* It's a freeable page by MADV_FREE */
> > + dec_mm_counter(mm, MM_ANONPAGES);
> > + goto discard;
> > + } else {
> > + set_pte_at(mm, address, pte, pteval);
> > + ret = SWAP_FAIL;
> > + goto out_unmap;
> > + }
> > + }
> > +
> > if (PageSwapCache(page)) {
> > /*
> > * Store the swap location in the pte.
> > @@ -1227,6 +1264,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
> > } else
> > dec_mm_counter(mm, MM_FILEPAGES);
> >
> > +discard:
> > page_remove_rmap(page);
> > page_cache_release(page);
> >
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index 6484195c6859..e3e026c6c7b1 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -713,13 +713,17 @@ enum page_references {
> > };
> >
> > static enum page_references page_check_references(struct page *page,
> > - struct scan_control *sc)
> > + struct scan_control *sc,
> > + bool *freeable)
> > {
> > int referenced_ptes, referenced_page;
> > unsigned long vm_flags;
> > + int pte_dirty;
> > +
> > + VM_BUG_ON_PAGE(!PageLocked(page), page);
> >
> > referenced_ptes = page_referenced(page, 1, sc->target_mem_cgroup,
> > - &vm_flags);
> > + &vm_flags, &pte_dirty);
> > referenced_page = TestClearPageReferenced(page);
> >
> > /*
> > @@ -760,6 +764,10 @@ static enum page_references page_check_references(struct page *page,
> > return PAGEREF_KEEP;
> > }
> >
> > + if (PageAnon(page) && !pte_dirty && !PageSwapCache(page) &&
> > + !PageDirty(page))
> > + *freeable = true;
> > +
> > /* Reclaim if clean, defer dirty pages to writeback */
> > if (referenced_page && !PageSwapBacked(page))
> > return PAGEREF_RECLAIM_CLEAN;
> > @@ -828,6 +836,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
> > int may_enter_fs;
> > enum page_references references = PAGEREF_RECLAIM_CLEAN;
> > bool dirty, writeback;
> > + bool freeable = false;
> >
> > cond_resched();
> >
> > @@ -950,7 +959,8 @@ static unsigned long shrink_page_list(struct list_head *page_list,
> > }
> >
> > if (!force_reclaim)
> > - references = page_check_references(page, sc);
> > + references = page_check_references(page, sc,
> > + &freeable);
> >
> > switch (references) {
> > case PAGEREF_ACTIVATE:
> > @@ -966,7 +976,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
> > * Anonymous process memory has backing store?
> > * Try to allocate it some swap space here.
> > */
> > - if (PageAnon(page) && !PageSwapCache(page)) {
> > + if (PageAnon(page) && !PageSwapCache(page) && !freeable) {
> > if (!(sc->gfp_mask & __GFP_IO))
> > goto keep_locked;
> > if (!add_to_swap(page, page_list))
> > @@ -981,8 +991,9 @@ static unsigned long shrink_page_list(struct list_head *page_list,
> > * The page is mapped into the page tables of one or more
> > * processes. Try to unmap it here.
> > */
> > - if (page_mapped(page) && mapping) {
> > - switch (try_to_unmap(page, ttu_flags)) {
> > + if (page_mapped(page) && (mapping || freeable)) {
> > + switch (try_to_unmap(page,
> > + freeable ? TTU_FREE : ttu_flags)) {
> > case SWAP_FAIL:
> > goto activate_locked;
> > case SWAP_AGAIN:
> > @@ -990,7 +1001,20 @@ static unsigned long shrink_page_list(struct list_head *page_list,
> > case SWAP_MLOCK:
> > goto cull_mlocked;
> > case SWAP_SUCCESS:
> > - ; /* try to free the page below */
> > + /* try to free the page below */
> > + if (!freeable)
> > + break;
> > + /*
> > + * Freeable anon page doesn't have mapping
> > + * due to skipping of swapcache so we free
> > + * page in here rather than __remove_mapping.
> > + */
> > + VM_BUG_ON_PAGE(PageSwapCache(page), page);
> > + if (!page_freeze_refs(page, 1))
> > + goto keep_locked;
> > + __clear_page_locked(page);
> > + count_vm_event(PGLAZYFREED);
> > + goto free_it;
> > }
> > }
> >
> > @@ -1730,7 +1754,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
> > }
> >
> > if (page_referenced(page, 0, sc->target_mem_cgroup,
> > - &vm_flags)) {
> > + &vm_flags, NULL)) {
> > nr_rotated += hpage_nr_pages(page);
> > /*
> > * Identify referenced, file-backed active pages and
> > diff --git a/mm/vmstat.c b/mm/vmstat.c
> > index 87273cddeca0..0b8fc1ac591a 100644
> > --- a/mm/vmstat.c
> > +++ b/mm/vmstat.c
> > @@ -817,6 +817,7 @@ const char * const vmstat_text[] = {
> >
> > "pgfault",
> > "pgmajfault",
> > + "pglazyfreed",
> >
> > TEXTS_FOR_ZONES("pgrefill")
> > TEXTS_FOR_ZONES("pgsteal_kswapd")
> > --
> > 2.0.0
> >
> > --
> > To unsubscribe, send a message with 'unsubscribe linux-mm' in
> > the body to majordomo@...ck.org. For more info on Linux MM,
> > see: http://www.linux-mm.org/ .
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>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@...ck.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a>
--
Kind regards,
Minchan Kim
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