Commit 0964730b authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

mlock: fix unevictable_pgs event counts on THP 



5.8 commit 5d91f31f ("mm: swap: fix vmstats for huge page") has
established that vm_events should count every subpage of a THP, including
unevictable_pgs_culled and unevictable_pgs_rescued; but
lru_cache_add_inactive_or_unevictable() was not doing so for
unevictable_pgs_mlocked, and mm/mlock.c was not doing so for
unevictable_pgs mlocked, munlocked, cleared and stranded.

Fix them; but THPs don't go the pagevec way in mlock.c, so no fixes needed
on that path.

Fixes: 5d91f31f ("mm: swap: fix vmstats for huge page")
Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Acked-by: default avatarYang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Qian Cai <cai@lca.pw>
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301408230.5954@eggly.anvils


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8d8869ca

mm/mlock.c

+15 −9
Original line number Diff line number Diff line
@@ -58,11 +58,14 @@ EXPORT_SYMBOL(can_do_mlock); 
 */

void clear_page_mlock(struct page *page)

{

	int nr_pages;



	if (!TestClearPageMlocked(page))

		return;



	mod_zone_page_state(page_zone(page), NR_MLOCK, -thp_nr_pages(page));

	count_vm_event(UNEVICTABLE_PGCLEARED);

	nr_pages = thp_nr_pages(page);

	mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);

	count_vm_events(UNEVICTABLE_PGCLEARED, nr_pages);

	/*

	 * The previous TestClearPageMlocked() corresponds to the smp_mb()

	 * in __pagevec_lru_add_fn().
@@ -76,7 +79,7 @@ void clear_page_mlock(struct page *page) 
		 * We lost the race. the page already moved to evictable list.

		 */

		if (PageUnevictable(page))

			count_vm_event(UNEVICTABLE_PGSTRANDED);

			count_vm_events(UNEVICTABLE_PGSTRANDED, nr_pages);

	}

}
@@ -93,9 +96,10 @@ void mlock_vma_page(struct page *page) 
	VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page);



	if (!TestSetPageMlocked(page)) {

		mod_zone_page_state(page_zone(page), NR_MLOCK,

				    thp_nr_pages(page));

		count_vm_event(UNEVICTABLE_PGMLOCKED);

		int nr_pages = thp_nr_pages(page);



		mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages);

		count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);

		if (!isolate_lru_page(page))

			putback_lru_page(page);

	}
@@ -138,7 +142,7 @@ static void __munlock_isolated_page(struct page *page) 


	/* Did try_to_unlock() succeed or punt? */

	if (!PageMlocked(page))

		count_vm_event(UNEVICTABLE_PGMUNLOCKED);

		count_vm_events(UNEVICTABLE_PGMUNLOCKED, thp_nr_pages(page));



	putback_lru_page(page);

}
@@ -154,10 +158,12 @@ static void __munlock_isolated_page(struct page *page) 
 */

static void __munlock_isolation_failed(struct page *page)

{

	int nr_pages = thp_nr_pages(page);



	if (PageUnevictable(page))

		__count_vm_event(UNEVICTABLE_PGSTRANDED);

		__count_vm_events(UNEVICTABLE_PGSTRANDED, nr_pages);

	else

		__count_vm_event(UNEVICTABLE_PGMUNLOCKED);

		__count_vm_events(UNEVICTABLE_PGMUNLOCKED, nr_pages);

}



/**

mm/swap.c

+3 −3
Original line number Diff line number Diff line
@@ -494,14 +494,14 @@ void lru_cache_add_inactive_or_unevictable(struct page *page, 


	unevictable = (vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) == VM_LOCKED;

	if (unlikely(unevictable) && !TestSetPageMlocked(page)) {

		int nr_pages = thp_nr_pages(page);

		/*

		 * We use the irq-unsafe __mod_zone_page_stat because this

		 * counter is not modified from interrupt context, and the pte

		 * lock is held(spinlock), which implies preemption disabled.

		 */

		__mod_zone_page_state(page_zone(page), NR_MLOCK,

				    thp_nr_pages(page));

		count_vm_event(UNEVICTABLE_PGMLOCKED);

		__mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages);

		count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);

	}

	lru_cache_add(page);

}

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