Subject: + 
mm-memory-failurec-recheck-pagehuge-after-hugetlb-page-migrate-successfully.patch
 added to -mm tree
To: [email protected],[email protected],[email protected]
From: [email protected]
Date: Mon, 16 Dec 2013 11:55:51 -0800


The patch titled
     Subject: mm/memory-failure.c: recheck PageHuge() after hugetlb page 
migrate successfully
has been added to the -mm tree.  Its filename is
     
mm-memory-failurec-recheck-pagehuge-after-hugetlb-page-migrate-successfully.patch

This patch should soon appear at
    
http://ozlabs.org/~akpm/mmots/broken-out/mm-memory-failurec-recheck-pagehuge-after-hugetlb-page-migrate-successfully.patch
and later at
    
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memory-failurec-recheck-pagehuge-after-hugetlb-page-migrate-successfully.patch

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------------------------------------------------------
From: Jianguo Wu <[email protected]>
Subject: mm/memory-failure.c: recheck PageHuge() after hugetlb page migrate 
successfully

After a successful hugetlb page migration by soft offline, the source page
will either be freed into hugepage_freelists or buddy(over-commit page). 
If page is in buddy, page_hstate(page) will be NULL.  It will hit a NULL
pointer dereference in dequeue_hwpoisoned_huge_page().

[  890.677918] BUG: unable to handle kernel NULL pointer dereference at
 0000000000000058
[  890.685741] IP: [<ffffffff81163761>]
dequeue_hwpoisoned_huge_page+0x131/0x1d0
[  890.692861] PGD c23762067 PUD c24be2067 PMD 0
[  890.697314] Oops: 0000 [#1] SMP

So check PageHuge(page) after call migrate_pages() successfully.

Signed-off-by: Jianguo Wu <[email protected]>
Tested-by: Naoya Horiguchi <[email protected]>
Reviewed-by: Naoya Horiguchi <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 mm/memory-failure.c |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff -puN 
mm/memory-failure.c~mm-memory-failurec-recheck-pagehuge-after-hugetlb-page-migrate-successfully
 mm/memory-failure.c
--- 
a/mm/memory-failure.c~mm-memory-failurec-recheck-pagehuge-after-hugetlb-page-migrate-successfully
+++ a/mm/memory-failure.c
@@ -1505,10 +1505,16 @@ static int soft_offline_huge_page(struct
                if (ret > 0)
                        ret = -EIO;
        } else {
-               set_page_hwpoison_huge_page(hpage);
-               dequeue_hwpoisoned_huge_page(hpage);
-               atomic_long_add(1 << compound_order(hpage),
-                               &num_poisoned_pages);
+               /* overcommit hugetlb page will be freed to buddy */
+               if (PageHuge(page)) {
+                       set_page_hwpoison_huge_page(hpage);
+                       dequeue_hwpoisoned_huge_page(hpage);
+                       atomic_long_add(1 << compound_order(hpage),
+                                       &num_poisoned_pages);
+               } else {
+                       SetPageHWPoison(page);
+                       atomic_long_inc(&num_poisoned_pages);
+               }
        }
        return ret;
 }
_

Patches currently in -mm which might be from [email protected] are

mm-memory-failurec-recheck-pagehuge-after-hugetlb-page-migrate-successfully.patch

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