From deb19aafd901b60f7192b1e16073ec6673d5c98b 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
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 3.10:
- adjust context]
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 | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
(limited to 'mm/memory-failure.c')
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 6a7f9cab4ddb..7e3601ce51c6 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1499,10 +1499,16 @@ static int soft_offline_huge_page(struct page *page, int flags)
pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
pfn, ret, page->flags);
} else {
- set_page_hwpoison_huge_page(hpage);
- dequeue_hwpoisoned_huge_page(hpage);
- atomic_long_add(1 << compound_trans_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);
+ }
}
/* keep elevated page count for bad page */
return ret;
--
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