Re: [PATCH v11 1/7] mm: support madvise(MADV_FREE)

[Zhang Yanfei]

On 07/08/2014 02:03 PM, Minchan Kim 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@blaptop:~/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@xxxxxxxxx>
> Cc: Linux API <linux-api@xxxxxxxxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Jason Evans <je@xxxxxx>
> Cc: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
> Acked-by: Rik van Riel <riel@xxxxxxxxxx>
> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>

A quick respin, looks good to me now for this !THP part. And
looks neat with the Pagewalker.

Acked-by: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>

> ---
>  include/linux/rmap.h                   |   9 ++-
>  include/linux/vm_event_item.h          |   1 +
>  include/uapi/asm-generic/mman-common.h |   1 +
>  mm/madvise.c                           | 135 +++++++++++++++++++++++++++++++++
>  mm/rmap.c                              |  42 +++++++++-
>  mm/vmscan.c                            |  40 ++++++++--
>  mm/vmstat.c                            |   1 +
>  7 files changed, 217 insertions(+), 12 deletions(-)
> 
> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> index be574506e6a9..0ba377b97a38 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);
>  
>  #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..a6aa7d4c4e02 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 +260,124 @@ 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_none(ptent))
> +			continue;
> +
> +		if (!pte_present(ptent))
> +			continue;
> +
> +		page = vm_normal_page(vma, addr, ptent);
> +		if (page && PageSwapCache(page)) {
> +			if (trylock_page(page)) {
> +				if (try_to_free_swap(page))
> +					ClearPageDirty(page);
> +				unlock_page(page);
> +			} else
> +				continue;
> +		}
> +
> +		/*
> +		 * 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 +508,13 @@ 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);
>  	case MADV_DONTNEED:
>  		return madvise_dontneed(vma, prev, start, end);
>  	default:
> @@ -400,6 +534,7 @@ 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 7928ddd91b6e..a8e34596dc97 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)) {
> +				set_pte_at(mm, address, pte, pteval);
> +				ret = SWAP_FAIL;
> +				goto out_unmap;
> +			} else {
> +				/* It's a freeable page by MADV_FREE */
> +				dec_mm_counter(mm, MM_ANONPAGES);
> +				goto discard;
> +			}
> +		}
> +
>  		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 6d24fd63b209..d88413ccadcc 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -707,13 +707,17 @@ 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);
>  
>  	/*
> @@ -754,6 +758,10 @@ 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;
> @@ -823,6 +831,7 @@ 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();
>  
> @@ -945,7 +954,8 @@ 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:
> @@ -961,7 +971,7 @@ 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))
> @@ -976,8 +986,9 @@ 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, ttu_flags |
> +					(freeable ? TTU_FREE : 0))) {
>  			case SWAP_FAIL:
>  				goto activate_locked;
>  			case SWAP_AGAIN:
> @@ -985,7 +996,20 @@ 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;
>  			}
>  		}
>  
> @@ -1727,7 +1751,7 @@ 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 eef6321c8470..da18337c6c66 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -794,6 +794,7 @@ const char * const vmstat_text[] = {
>  
>  	"pgfault",
>  	"pgmajfault",
> +	"pglazyfreed",
>  
>  	TEXTS_FOR_ZONES("pgrefill")
>  	TEXTS_FOR_ZONES("pgsteal_kswapd")
> 


-- 
Thanks.
Zhang Yanfei
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