From mboxrd@z Thu Jan  1 00:00:00 1970
From: Glauber Costa <glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
Subject: Re: [PATCH v3 16/28] memcg: kmem controller charge/uncharge infrastructure
Date: Wed, 30 May 2012 16:26:28 +0400
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To: Frederic Weisbecker <fweisbec-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>, Greg Thelen <gthelen-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Suleiman Souhlal <suleiman-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, devel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, David Rientjes <rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Christoph Lameter <cl-vYTEC60ixJUAvxtiuMwx3w@public.gmane.org>, Pekka Enberg <penberg-bbCR+/B0CizivPeTLB3BmA@public.gmane.org>

On 05/30/2012 04:17 PM, Frederic Weisbecker wrote:
> On Fri, May 25, 2012 at 05:03:36PM +0400, Glauber Costa wrote:
>>   #endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
>> +static __always_inline struct kmem_cache *
>> +mem_cgroup_get_kmem_cache(struct kmem_cache *cachep, gfp_t gfp)
>> +{
>> +	if (!mem_cgroup_kmem_on)
>> +		return cachep;
>> +	if (!current->mm)
>> +		return cachep;
>> +	if (in_interrupt())
>> +		return cachep;
>
> Does that mean interrupts are kept out of accounting?

Well, since interrupts have no process context, if you are in an 
interrupt I can't think of any sane thing to do than relay it to the 
root memcg. That's what happen when I return cachep: I return the 
original parent cache, and we allocate from that.