Commit b985194c authored May 22, 2014 by Chen Yucong Committed by Linus Torvalds May 23, 2014

hwpoison, hugetlb: lock_page/unlock_page does not match for handling a free hugepage



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 <slaoub@gmail.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Tested-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: <stable@vger.kernel.org>	[2.6.36+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 4b660a7f

mm/memory-failure.c

+8 −7

Original line number	Diff line number	Diff line
		@@ -1081,16 +1081,17 @@ 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))
		if (PageHWPoison(hpage)) {
		if ((hwpoison_filter(p) && TestClearPageHWPoison(p))
		\|\| (p != hpage && TestSetPageHWPoison(hpage))) {
		atomic_long_sub(nr_pages, &num_poisoned_pages);
		unlock_page(hpage);
		return 0;
		}
		}
		set_page_hwpoison_huge_page(hpage);
		res = dequeue_hwpoisoned_huge_page(hpage);
		action_result(pfn, "free huge",

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