From d60608770339d22933f0a6f1b859880799c9365d Mon Sep 17 00:00:00 2001 From: Chen Yucong Date: Thu, 22 May 2014 11:54:15 -0700 Subject: [PATCH] hwpoison, hugetlb: lock_page/unlock_page does not match for handling a free hugepage commit b985194c8c0a130ed155b71662e39f7eaea4876f upstream. For handling a free hugepage in memory failure, the race will happen if another thread hwpoisoned this hugepage concurrently. So we need to check PageHWPoison instead of !PageHWPoison. If hwpoison_filter(p) returns true or a race happens, then we need to unlock_page(hpage). Signed-off-by: Chen Yucong Reviewed-by: Naoya Horiguchi Tested-by: Naoya Horiguchi Reviewed-by: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [bwh: Backported to 3.2: s/num_poisoned_pages/bad_mce_pages/] Signed-off-by: Ben Hutchings --- mm/memory-failure.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 96c4bcf188b1..1f5fdb7914f7 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1033,15 +1033,16 @@ int __memory_failure(unsigned long pfn, int trapno, int flags) return 0; } else if (PageHuge(hpage)) { /* - * Check "just unpoisoned", "filter hit", and - * "race with other subpage." + * Check "filter hit" and "race with other subpage." */ lock_page(hpage); - if (!PageHWPoison(hpage) - || (hwpoison_filter(p) && TestClearPageHWPoison(p)) - || (p != hpage && TestSetPageHWPoison(hpage))) { - atomic_long_sub(nr_pages, &mce_bad_pages); - return 0; + if (PageHWPoison(hpage)) { + if ((hwpoison_filter(p) && TestClearPageHWPoison(p)) + || (p != hpage && TestSetPageHWPoison(hpage))) { + atomic_long_sub(nr_pages, &mce_bad_pages); + unlock_page(hpage); + return 0; + } } set_page_hwpoison_huge_page(hpage); res = dequeue_hwpoisoned_huge_page(hpage); -- 2.47.3