From eb94a8784427b28479f871b5d4121c547808d0fc Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Wed, 3 May 2017 14:52:36 -0700 Subject: [PATCH] mm: fix lazyfree BUG_ON check in try_to_unmap_one() If a page is swapbacked, it means it should be in swapcache in try_to_unmap_one's path. If a page is !swapbacked, it mean it shouldn't be in swapcache in try_to_unmap_one's path. Check both two cases all at once and if it fails, warn and return SWAP_FAIL. Such bug never mean we should shut down the kernel. [minchan@kernel.org: do not use VM_WARN_ON_ONCE as if condition[ Link: http://lkml.kernel.org/r/20170309060226.GB854@bbox Link: http://lkml.kernel.org/r/20170307055551.GC29458@bbox Signed-off-by: Minchan Kim Suggested-by: Johannes Weiner Acked-by: Michal Hocko Acked-by: Johannes Weiner Cc: Shaohua Li Cc: Hillf Danton Cc: Hugh Dickins Cc: Rik van Riel Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/rmap.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index 519b7eb723d1..a19bd8b8ab0d 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1418,8 +1418,12 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, * Store the swap location in the pte. * See handle_pte_fault() ... */ - VM_BUG_ON_PAGE(!PageSwapCache(page) && PageSwapBacked(page), - page); + if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) { + WARN_ON_ONCE(1); + ret = SWAP_FAIL; + page_vma_mapped_walk_done(&pvmw); + break; + } /* MADV_FREE page check */ if (!PageSwapBacked(page)) { -- 2.11.0