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Subject: Re: [Cluster-devel] [PATCH] gfs2: add error handling for
 kmem_cache_zalloc
To:     "cgxu519@gmx.com" <cgxu519@gmx.com>,
        Zhouyang Jia <jiazhouyang09@gmail.com>
Cc:     cluster-devel@redhat.com, linux-kernel@vger.kernel.org
References: <1528774692-38990-1-git-send-email-jiazhouyang09@gmail.com>
 <C20C8754-0C63-4EB2-B3E9-68E4EE29338D@gmx.com>
From:   Steven Whitehouse <swhiteho@redhat.com>
Message-ID: <bd3892fd-e8f7-fd5f-bc85-b3a55301bebd@redhat.com>
Date:   Tue, 12 Jun 2018 13:18:44 +0100
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Hi,


On 12/06/18 08:24, cgxu519@gmx.com wrote:
>> ?? 2018??6??12?գ?????11:38??Zhouyang Jia <jiazhouyang09@gmail.com> д????
>>
>> When kmem_cache_zalloc fails, the lack of error-handling code may
>> cause unexpected results.
>>
>> This patch adds error-handling code after calling kmem_cache_zalloc.
> Should not fail on this case.
>
> Thanks,
> Chengguang.
Indeed. It is one of the few GFP_NOFAIL allocations left in GFS2. It 
would be good to figure out how to remove the last few of these 
allocations, but simply adding a check for a NULL return is not the 
right solution here anyway. I would also add that if this problem was 
easier then I'm sure we'd have solved it before - the right answer is 
not very obvious in this case,

Steve.

>
>> Signed-off-by: Zhouyang Jia <jiazhouyang09@gmail.com>
>> ---
>> fs/gfs2/trans.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/fs/gfs2/trans.c b/fs/gfs2/trans.c
>> index 064c9a0..da81eb4 100644
>> --- a/fs/gfs2/trans.c
>> +++ b/fs/gfs2/trans.c
>> @@ -130,6 +130,9 @@ static struct gfs2_bufdata *gfs2_alloc_bufdata(struct gfs2_glock *gl,
>> 	struct gfs2_bufdata *bd;
>>
>> 	bd = kmem_cache_zalloc(gfs2_bufdata_cachep, GFP_NOFS | __GFP_NOFAIL);
>> +	if (!bd)
>> +		return NULL;
>> +
>> 	bd->bd_bh = bh;
>> 	bd->bd_gl = gl;
>> 	bd->bd_ops = lops;
>> -- 
>> 2.7.4
>>
>