+ hwposion-hugetlb-lock_page-unlock_page-does-not-match-for-handling-a-free-hugepage.patch added to -mm tree

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Subject: + hwposion-hugetlb-lock_page-unlock_page-does-not-match-for-handling-a-free-hugepage.patch added to -mm tree
To: slaoub@xxxxxxxxx,ak@xxxxxxxxxxxxxxx,n-horiguchi@xxxxxxxxxxxxx,stable@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 12 May 2014 15:56:24 -0700


The patch titled
     Subject: HWPOSION, hugetlb: lock_page/unlock_page does not match for handling a free hugepage
has been added to the -mm tree.  Its filename is
     hwposion-hugetlb-lock_page-unlock_page-does-not-match-for-handling-a-free-hugepage.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/hwposion-hugetlb-lock_page-unlock_page-does-not-match-for-handling-a-free-hugepage.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/hwposion-hugetlb-lock_page-unlock_page-does-not-match-for-handling-a-free-hugepage.patch

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------------------------------------------------------
From: Chen Yucong <slaoub@xxxxxxxxx>
Subject: HWPOSION, 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@xxxxxxxxx>
Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Tested-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Reviewed-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>	[2.6.36+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/memory-failure.c |   15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff -puN mm/memory-failure.c~hwposion-hugetlb-lock_page-unlock_page-does-not-match-for-handling-a-free-hugepage mm/memory-failure.c
--- a/mm/memory-failure.c~hwposion-hugetlb-lock_page-unlock_page-does-not-match-for-handling-a-free-hugepage
+++ a/mm/memory-failure.c
@@ -1081,15 +1081,16 @@ int memory_failure(unsigned long pfn, in
 			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))
-			    || (p != hpage && TestSetPageHWPoison(hpage))) {
-				atomic_long_sub(nr_pages, &num_poisoned_pages);
-				return 0;
+			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);
_

Patches currently in -mm which might be from slaoub@xxxxxxxxx are

hwposion-hugetlb-lock_page-unlock_page-does-not-match-for-handling-a-free-hugepage.patch

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