linux-kernel - Re: [PATCH] mm/ksm: return NULL when doesn't get mergeable page

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Message-ID: <523E3FC6.7020009@huawei.com>
Date:	Sun, 22 Sep 2013 08:54:30 +0800
From:	Jianguo Wu <wujianguo@...wei.com>
To:	Petr Holasek <pholasek@...hat.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>, Mel Gorman <mgorman@...e.de>,
	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm/ksm: return NULL when doesn't get mergeable page

On 2013/9/19 16:33, Petr Holasek wrote:

> On Mon, 16 Sep 2013, Jianguo Wu wrote:
>> In get_mergeable_page() local variable page is not initialized,
>> it may hold a garbage value, when find_mergeable_vma() return NULL,
>> get_mergeable_page() may return a garbage value to the caller.
>>
>> So initialize page as NULL.
>>
>> Signed-off-by: Jianguo Wu <wujianguo@...wei.com>
>> ---
>>  mm/ksm.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/mm/ksm.c b/mm/ksm.c
>> index b6afe0c..87efbae 100644
>> --- a/mm/ksm.c
>> +++ b/mm/ksm.c
>> @@ -460,7 +460,7 @@ static struct page *get_mergeable_page(struct rmap_item *rmap_item)
>>  	struct mm_struct *mm = rmap_item->mm;
>>  	unsigned long addr = rmap_item->address;
>>  	struct vm_area_struct *vma;
>> -	struct page *page;
>> +	struct page *page = NULL;
>>  
>>  	down_read(&mm->mmap_sem);
>>  	vma = find_mergeable_vma(mm, addr);
>> -- 
>> 1.7.1
>>
> 
> When find_mergeable_vma returned NULL, NULL is assigned to page in "out"
> statement.
> 

Oh, yes, thanks, Petr.

> 



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