Hi Greg,
Please queue this for 3.4 stable kernel. I adjust context and can be applied
to 3.4 stable clean.
---
From: Jianguo Wu <wujianguo@xxxxxxxxxx>
Date: Wed, 18 Dec 2013 17:08:54 -0800
Subject: [PATCH] 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@xxxxxxxxxx>
Tested-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
[wujg: backport to 3.4:
- adjust context
- s/num_poisoned_pages/mce_bad_pages/]
---
mm/memory-failure.c | 16 ++++++++++++----
1 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index d86fb20..7e95698 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1447,10 +1447,18 @@ static int soft_offline_huge_page(struct page *page, int flags)
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;
}
-- 1.7.7
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