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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: 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 @@ 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