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mm/memory-failure: fix race with compound page split/merge 

get_hwpoison_page() must recheck relation between head and tail pages.

n-horiguchi said: without this recheck, the race causes kernel to pin an
irrelevant page, and finally makes kernel crash for refcount mismatch.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Konstantin Khlebnikov 2016-04-28 16:19:03 -07:00 committed by Linus Torvalds
parent b73413647e
commit c2e7e00b71
1 changed files with 9 additions and 1 deletions
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10
mm/memory-failure.c
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@ -888,7 +888,15 @@ int get_hwpoison_page(struct page *page)
}
}
return get_page_unless_zero(head);
if (get_page_unless_zero(head)) {
if (head == compound_head(page))
return 1;
pr_info("MCE: %#lx cannot catch tail\n", page_to_pfn(page));
put_page(head);
}
return 0;
}
EXPORT_SYMBOL_GPL(get_hwpoison_page);