From a363d1224b5add67a7cafab9fdb9f19d569fbe98 Mon Sep 17 00:00:00 2001 From: Miaohe Lin Date: Tue, 11 Jul 2023 13:50:15 +0800 Subject: [PATCH] mm: memory-failure: fetch compound head after extra page refcnt is held Page might become thp, huge page or being splited after compound head is fetched but before page refcnt is bumped. So hpage might be a tail page leading to VM_BUG_ON_PAGE(PageTail(page)) in PageTransHuge(). Link: https://lkml.kernel.org/r/20230711055016.2286677-8-linmiaohe@huawei.com Fixes: 415c64c1453a ("mm/memory-failure: split thp earlier in memory error handling") Signed-off-by: Miaohe Lin Acked-by: Naoya Horiguchi Signed-off-by: Andrew Morton --- mm/memory-failure.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 36529f3c6554..133737580a7e 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -2175,8 +2175,6 @@ try_again: goto unlock_mutex; } - hpage = compound_head(p); - /* * We need/can do nothing about count=0 pages. * 1) it's a free page, and therefore in safe hand: @@ -2215,6 +2213,7 @@ try_again: } } + hpage = compound_head(p); if (PageTransHuge(hpage)) { /* * The flag must be set after the refcount is bumped -- 2.11.0