Commit ef2a2cbd authored Jul 31, 2013 by Naoya Horiguchi Committed by Linus Torvalds Jul 31, 2013

mm/swap.c: clear PageActive before adding pages onto unevictable list



As a result of commit 13f7f789 ("mm: pagevec: defer deciding which
LRU to add a page to until pagevec drain time"), pages on unevictable
lists can have both of PageActive and PageUnevictable set.  This is not
only confusing, but also corrupts page migration and
shrink_[in]active_list.

This patch fixes the problem by adding ClearPageActive before adding
pages into unevictable list.  It also cleans up VM_BUG_ONs.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 31a1b26f

mm/swap.c

+2 −7

Original line number	Diff line number	Diff line
		@@ -512,12 +512,7 @@ EXPORT_SYMBOL(__lru_cache_add);
		*/
		void lru_cache_add(struct page *page)
		{
		if (PageActive(page)) {
		VM_BUG_ON(PageUnevictable(page));
		} else if (PageUnevictable(page)) {
		VM_BUG_ON(PageActive(page));
		}

		VM_BUG_ON(PageActive(page) && PageUnevictable(page));
		VM_BUG_ON(PageLRU(page));
		__lru_cache_add(page);
		}
		@@ -539,6 +534,7 @@ void add_page_to_unevictable_list(struct page *page)

		spin_lock_irq(&zone->lru_lock);
		lruvec = mem_cgroup_page_lruvec(page, zone);
		ClearPageActive(page);
		SetPageUnevictable(page);
		SetPageLRU(page);
		add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE);
		@@ -833,7 +829,6 @@ static void __pagevec_lru_add_fn(struct page page, struct lruvec lruvec,
		int active = PageActive(page);
		enum lru_list lru = page_lru(page);

		VM_BUG_ON(PageUnevictable(page));
		VM_BUG_ON(PageLRU(page));

		SetPageLRU(page);

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