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mm: memory-failure: fetch compound head after extra page refcnt is held

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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: 415c64c145 ("mm/memory-failure: split thp earlier in memory error handling")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Miaohe Lin 2023-07-11 13:50:15 +08:00 committed by Andrew Morton
parent 5885c6a625
commit a363d1224b
1 changed files with 1 additions and 2 deletions
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3
mm/memory-failure.c
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@ -2175,8 +2175,6 @@ int memory_failure(unsigned long pfn, int flags)
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 @@ int memory_failure(unsigned long pfn, int flags)
}
}
hpage = compound_head(p);
if (PageTransHuge(hpage)) {
/*
* The flag must be set after the refcount is bumped