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From: Wen Yang <wen.yang99@zte.com.cn>
To: linux-mm@kvack.org
Cc: akpm@linux-foundation.org, mhocko@suse.com, vbabka@suse.cz,
	kirill.shutemov@linux.intel.com, hannes@cmpxchg.org,
	linux-kernel@vger.kernel.org, wen.yang99@zte.com.cn,
	jiang.biao2@zte.com.cn
Subject: [PATCH] mm/vmstat: fix divide error at __fragmentation_index
Date: Thu, 3 Aug 2017 17:12:00 +0800	[thread overview]
Message-ID: <1501751520-2598-1-git-send-email-wen.yang99@zte.com.cn> (raw)

When order is -1 or too big, *1UL << order* will be 0, which will
cause divide error. Although it seems that all callers of
__fragmentation_index() will only do so with a valid order, the
patch can make it more robust.

Sugguested-by: VlastimilBabka <vbabka@suse.cz>
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
---
 mm/vmstat.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 76f7367..6f0f1ae 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -870,6 +870,9 @@ static int __fragmentation_index(unsigned int order, struct contig_page_info *in
 {
 	unsigned long requested = 1UL << order;
 
+	if (WARN_ON_ONCE(order >= MAX_ORDER))
+		return 0;
+
 	if (!info->free_blocks_total)
 		return 0;
 
-- 
2.7.4

WARNING: multiple messages have this Message-ID (diff)
From: Wen Yang <wen.yang99@zte.com.cn>
To: linux-mm@kvack.org
Cc: akpm@linux-foundation.org, mhocko@suse.com, vbabka@suse.cz,
	kirill.shutemov@linux.intel.com, hannes@cmpxchg.org,
	linux-kernel@vger.kernel.org, wen.yang99@zte.com.cn,
	jiang.biao2@zte.com.cn
Subject: [PATCH] mm/vmstat: fix divide error at __fragmentation_index
Date: Thu, 3 Aug 2017 17:12:00 +0800	[thread overview]
Message-ID: <1501751520-2598-1-git-send-email-wen.yang99@zte.com.cn> (raw)

When order is -1 or too big, *1UL << order* will be 0, which will
cause divide error. Although it seems that all callers of
__fragmentation_index() will only do so with a valid order, the
patch can make it more robust.

Sugguested-by: VlastimilBabka <vbabka@suse.cz>
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
---
 mm/vmstat.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 76f7367..6f0f1ae 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -870,6 +870,9 @@ static int __fragmentation_index(unsigned int order, struct contig_page_info *in
 {
 	unsigned long requested = 1UL << order;
 
+	if (WARN_ON_ONCE(order >= MAX_ORDER))
+		return 0;
+
 	if (!info->free_blocks_total)
 		return 0;
 
-- 
2.7.4


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             reply	other threads:[~2017-08-03  9:00 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-03  9:12 Wen Yang [this message]
2017-08-03  9:12 ` [PATCH] mm/vmstat: fix divide error at __fragmentation_index Wen Yang
  -- strict thread matches above, loose matches on Subject: below --
2017-08-03  8:46 jiang.biao2
2017-08-03  7:59 Wen Yang
2017-08-03  7:59 ` Wen Yang
2017-08-03  8:09 ` Vlastimil Babka
2017-08-03  8:09   ` Vlastimil Babka

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