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	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>
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					 1 changed files with 8 additions and 7 deletions
				
			
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			@ -1081,15 +1081,16 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
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			return 0;
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		} else if (PageHuge(hpage)) {
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			/*
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			 * Check "just unpoisoned", "filter hit", and
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			 * "race with other subpage."
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			 * Check "filter hit" and "race with other subpage."
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			 */
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			lock_page(hpage);
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			if (!PageHWPoison(hpage)
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			    || (hwpoison_filter(p) && TestClearPageHWPoison(p))
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			    || (p != hpage && TestSetPageHWPoison(hpage))) {
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				atomic_long_sub(nr_pages, &num_poisoned_pages);
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				return 0;
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			if (PageHWPoison(hpage)) {
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				if ((hwpoison_filter(p) && TestClearPageHWPoison(p))
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				    || (p != hpage && TestSetPageHWPoison(hpage))) {
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					atomic_long_sub(nr_pages, &num_poisoned_pages);
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					unlock_page(hpage);
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					return 0;
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				}
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			}
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			set_page_hwpoison_huge_page(hpage);
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			res = dequeue_hwpoisoned_huge_page(hpage);
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