--- /dev/null
+From a49ecbcd7b0d5a1cda7d60e03df402dd0ef76ac8 Mon Sep 17 00:00:00 2001
+From: Jianguo Wu <wujianguo@huawei.com>
+Date: Wed, 18 Dec 2013 17:08:54 -0800
+Subject: mm/memory-failure.c: recheck PageHuge() after hugetlb page migrate successfully
+
+From: Jianguo Wu <wujianguo@huawei.com>
+
+commit a49ecbcd7b0d5a1cda7d60e03df402dd0ef76ac8 upstream.
+
+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().
+
+ BUG: unable to handle kernel NULL pointer dereference at 0000000000000058
+ IP: [<ffffffff81163761>] dequeue_hwpoisoned_huge_page+0x131/0x1d0
+ PGD c23762067 PUD c24be2067 PMD 0
+ Oops: 0000 [#1] SMP
+
+So check PageHuge(page) after call migrate_pages() successfully.
+
+[wujg: backport to 3.4:
+ - adjust context
+ - s/num_poisoned_pages/mce_bad_pages/]
+
+Signed-off-by: Jianguo Wu <wujianguo@huawei.com>
+Tested-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
+Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+
+---
+ mm/memory-failure.c | 16 ++++++++++++----
+ 1 file changed, 12 insertions(+), 4 deletions(-)
+
+--- a/mm/memory-failure.c
++++ b/mm/memory-failure.c
+@@ -1447,10 +1447,18 @@ static int soft_offline_huge_page(struct
+ return ret;
+ }
+ done:
+- if (!PageHWPoison(hpage))
+- atomic_long_add(1 << compound_trans_order(hpage), &mce_bad_pages);
+- set_page_hwpoison_huge_page(hpage);
+- dequeue_hwpoisoned_huge_page(hpage);
++ /* overcommit hugetlb page will be freed to buddy */
++ if (PageHuge(hpage)) {
++ if (!PageHWPoison(hpage))
++ atomic_long_add(1 << compound_trans_order(hpage),
++ &mce_bad_pages);
++ set_page_hwpoison_huge_page(hpage);
++ dequeue_hwpoisoned_huge_page(hpage);
++ } else {
++ SetPageHWPoison(page);
++ atomic_long_inc(&mce_bad_pages);
++ }
++
+ /* keep elevated page count for bad page */
+ return ret;
+ }