Re: [PATCH] mm/slub: make add_full() condition more explicit

[Abel Wu]

On 2020/8/20 3:37, Andrew Morton wrote:
> On Tue, 11 Aug 2020 10:02:36 +0800 <wuyun.wu@xxxxxxxxxx> wrote:
> 
>> From: Abel Wu <wuyun.wu@xxxxxxxxxx>
>>
>> The commit below is incomplete, as it didn't handle the add_full() part.
>> commit a4d3f8916c65 ("slub: remove useless kmem_cache_debug() before remove_full()")
>>
>> This patch checks for SLAB_STORE_USER instead of kmem_cache_debug(),
>> since that should be the only context in which we need the list_lock for
>> add_full().
>>
> 
> Does this contradict what the comment tells us?
> 
> * This also ensures that the scanning of full
> * slabs from diagnostic functions will not see
> * any frozen slabs.
> 
I don't think so. If the flag SLAB_STORE_USER is not set, the slab won't
be added to the full list no matter this patch is applied or not, since
the check inside add_full() will guard for that. Am I missing something
here?
Regards,
	Abel