linux-kernel - Re: [PATCH 1/1] mm/slab: remove duplicate check in create

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Message-ID: <bce65264-40f2-4b38-839f-e0d58eda03a8@huawei.com>
Date: Tue, 8 Oct 2024 11:29:31 +0800
From: "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
To: Vlastimil Babka <vbabka@...e.cz>, Christoph Lameter <cl@...ux.com>, Pekka
 Enberg <penberg@...nel.org>, David Rientjes <rientjes@...gle.com>, Joonsoo
 Kim <iamjoonsoo.kim@....com>, Andrew Morton <akpm@...ux-foundation.org>,
	Roman Gushchin <roman.gushchin@...ux.dev>, Hyeonggon Yoo
	<42.hyeyoo@...il.com>, <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] mm/slab: remove duplicate check in create_cache()



On 2024/10/2 20:09, Vlastimil Babka wrote:
> On 8/21/24 05:26, Zhen Lei wrote:
>> The WARN_ON() check in static function create_cache() is done by its only
>> parent kmem_cache_create_usercopy() before calling it.
>> 	if (...
>> 	    WARN_ON(size < usersize || size - usersize < useroffset))
>> 		usersize = useroffset = 0;
>> 	...
>> 	s = create_cache(..., size, ..., useroffset, usersize, ...);
>>
>> Therefore, the WARN_ON() check in create_cache() can be safely removed.
>>
>> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
> 
> Hi, sorry for the late reply.
It doesn't matter, because the compiler will optimize it. It just saves
the reader a little time.

> This code was heavily refactored as of 6.12-rc1. Can you check if it's still
> the case and send updated patch?

It is still there. I'll post v2 later.

> Thanks,
> Vlastimil
> 
>> ---
>>  mm/slab_common.c | 3 ---
>>  1 file changed, 3 deletions(-)
>>
>> diff --git a/mm/slab_common.c b/mm/slab_common.c
>> index 40b582a014b8f2f..3069c9095523484 100644
>> --- a/mm/slab_common.c
>> +++ b/mm/slab_common.c
>> @@ -210,9 +210,6 @@ static struct kmem_cache *create_cache(const char *name,
>>  	struct kmem_cache *s;
>>  	int err;
>>  
>> -	if (WARN_ON(useroffset + usersize > object_size))
>> -		useroffset = usersize = 0;
>> -
>>  	err = -ENOMEM;
>>  	s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
>>  	if (!s)
> 
> .
> 

-- 
Regards,
  Zhen Lei