From: Jianguo Wu <wujianguo@huawei.com>
Date: Thu, 19 Dec 2013 01:08:54 +0000 (-0800)
Subject: mm/memory-failure.c: recheck PageHuge() after hugetlb page migrate successfully
X-Git-Tag: v3.2.55~60
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0ebf55cff9dbe3202a9ad98d3e9f1b3dc3b4fabe;p=pandora-kernel.git

mm/memory-failure.c: recheck PageHuge() after hugetlb page migrate successfully

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.

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>
[wujg: backport to 3.4:
 - adjust context
 - s/num_poisoned_pages/mce_bad_pages/]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

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