linux-kernel - Re: a question about slub in function __slab

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Date:	Thu, 3 Mar 2016 09:26:53 +0800
From:	Xishi Qiu <qiuxishi@...wei.com>
To:	Joonsoo Kim <js1304@...il.com>
CC:	LKML <linux-kernel@...r.kernel.org>, Linux MM <linux-mm@...ck.org>
Subject: Re: a question about slub in function __slab_free()

On 2016/3/2 22:38, Joonsoo Kim wrote:

> 2016-03-02 21:26 GMT+09:00 Xishi Qiu <qiuxishi@...wei.com>:
>> ___slab_alloc()
>>         deactivate_slab()
>>                 add_full(s, n, page);
>> The page will be added to full list and the frozen is 0, right?
>>
>> __slab_free()
>>         prior = page->freelist;  // prior is NULL
>>         was_frozen = new.frozen;  // was_frozen is 0
>>         ...
>>                 /*
>>                  * Slab was on no list before and will be
>>                  * partially empty
>>                  * We can defer the list move and instead
>>                  * freeze it.
>>                  */
>>                 new.frozen = 1;
>>         ...
>>
>> I don't understand why "Slab was on no list before"?
> 
> add_full() is defined only for CONFIG_SLUB_DEBUG.
> And, actual add happens if slub_debug=u is enabled.
> In other cases, fully used slab isn't attached on any list.
> 
> Thanks.
> 

Hi Joonsoo,

You are right, thank you very much!

>