[PATCH] gfs2: add error handling for kmem_cache_zalloc

[PATCH] gfs2: add error handling for kmem_cache_zalloc

[Zhouyang Jia]

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.

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

Re: [PATCH] gfs2: add error handling for kmem_cache_zalloc

[cgxu519]

> 在 2018年6月12日，上午11:38，Zhouyang Jia <jiazhouyang09@gmail.com> 写道：
> 
> 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.


> 
> 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
> 

Re: [PATCH] gfs2: add error handling for kmem_cache_zalloc

[Andreas Gruenbacher]

On 12 June 2018 at 09:24, cgxu519@gmx.com <cgxu519@gmx.com> wrote:
>
>> 在 2018年6月12日，上午11:38，Zhouyang Jia <jiazhouyang09@gmail.com> 写道：
>>
>> 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.

Indeed, with the __GFP_NOFAIL flag, kmem_cache_zalloc will not fail.
This is documented in include/linux/gfp.h.

Thanks,
Andreas

Re: [Cluster-devel] [PATCH] gfs2: add error handling for kmem_cache_zalloc

[Steven Whitehouse]

Hi,


On 12/06/18 08:24, cgxu519@gmx.com wrote:
>> 在 2018年6月12日，上午11:38，Zhouyang Jia <jiazhouyang09@gmail.com> 写道：
>>
>> 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
>>
>