From mboxrd@z Thu Jan  1 00:00:00 1970
From: Glauber Costa <glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
Subject: Re: PROBLEM: Crash cgdeleting empty memory cgroups with
	memory.kmem.limit_in_bytes set
Date: Thu, 21 Feb 2013 19:44:30 +0400
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To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Steffen Michalke <StMichalke-S0/GAf8tV78@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
List-Id: containers.vger.kernel.org

On 02/21/2013 03:22 PM, Glauber Costa wrote:
> On 02/21/2013 03:00 AM, Tejun Heo wrote:
>> (cc'ing cgroup / memcg people and quoting whole body)
>>
>> Looks like something is going wrong with memcg cache destruction.
>> Glauber, any ideas?  Also, can we please not use names as generic as
>> kmem_cache_destroy_work_func for something specific to memcg?  How
>> about something like memcg_destroy_cache_workfn?
>>
>> Thanks.
> 
> Steffen,
> 
> Is there any chance you could test that using SLAB instead of SLUB?
> I haven't manage to reproduce it yet, but I am working on some theories
> about why this is happening. If I could at least know if this is likely
> a cache problem vs a inner-memcg problem, that would help. The calltrace
> is not incredibly helpful, but it does indicate that the problem happens
> when freeing cache objects.
> 

Update:

I've already reproduced this and determined this is a problem that
plagues slub only, most likely due to initialization of the node caches.
But I still don't know for sure the exact location. Expect a patch by
tomorrow.