Subject: + 
hwposion-hugetlb-lock_page-unlock_page-does-not-match-for-handling-a-free-hugepage.patch
 added to -mm tree
To: 
sla...@gmail.com,a...@linux.intel.com,n-horigu...@ah.jp.nec.com,stable@vger.kernel.org
From: a...@linux-foundation.org
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 <sla...@gmail.com>
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 <sla...@gmail.com>
Reviewed-by: Naoya Horiguchi <n-horigu...@ah.jp.nec.com>
Tested-by: Naoya Horiguchi <n-horigu...@ah.jp.nec.com>
Reviewed-by: Andi Kleen <a...@linux.intel.com>
Cc: <stable@vger.kernel.org>    [2.6.36+]
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
---

 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 sla...@gmail.com are

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

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