linux-kernel - [PATCH] mm/hugetlb: check for pte NULL pointer in __page_check

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Message-ID: <52AEC8FD.6050200@huawei.com>
Date:	Mon, 16 Dec 2013 17:33:49 +0800
From:	Jianguo Wu <wujianguo@...wei.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	<kirill.shutemov@...ux.intel.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Mel Gorman <mgorman@...e.de>, <linux-mm@...ck.org>,
	<linux-kernel@...r.kernel.org>, qiuxishi <qiuxishi@...wei.com>,
	Hanjun Guo <guohanjun@...wei.com>
Subject: [PATCH] mm/hugetlb: check for pte NULL pointer in __page_check_address()

In __page_check_address(), if address's pud is not present,
huge_pte_offset() will return NULL, we should check the return value.

Signed-off-by: Jianguo Wu <wujianguo@...wei.com>
---
 mm/rmap.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index 55c8b8d..068522d 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -600,7 +600,11 @@ pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
 	spinlock_t *ptl;
 
 	if (unlikely(PageHuge(page))) {
+		/* when pud is not present, pte will be NULL */
 		pte = huge_pte_offset(mm, address);
+		if (!pte)
+			return NULL;
+
 		ptl = huge_pte_lockptr(page_hstate(page), mm, pte);
 		goto check;
 	}
-- 
1.7.1


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