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Date: Wed, 19 Sep 2012 11:39:33 +0400
From: Glauber Costa <glommer@parallels.com>
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To: Christoph Lameter <cl@linux.com>
CC: <linux-kernel@vger.kernel.org>, <cgroups@vger.kernel.org>,
        <kamezawa.hiroyu@jp.fujitsu.com>, <devel@openvz.org>,
        Tejun Heo <tj@kernel.org>, <linux-mm@kvack.org>,
        Suleiman Souhlal <suleiman@google.com>,
        Frederic Weisbecker <fweisbec@gmail.com>, Mel Gorman <mgorman@suse.de>,
        David Rientjes <rientjes@google.com>,
        Pekka Enberg <penberg@cs.helsinki.fi>, Michal Hocko <mhocko@suse.cz>,
        Johannes Weiner <hannes@cmpxchg.org>, Rik van Riel <riel@redhat.com>,
        Mel Gorman <mel@csn.ul.ie>
Subject: Re: [PATCH v3 05/13] Add a __GFP_KMEMCG flag
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On 09/18/2012 07:06 PM, Christoph Lameter wrote:
> On Tue, 18 Sep 2012, Glauber Costa wrote:
> 
>> +++ b/include/linux/gfp.h
>> @@ -35,6 +35,11 @@ struct vm_area_struct;
>>  #else
>>  #define ___GFP_NOTRACK		0
>>  #endif
>> +#ifdef CONFIG_MEMCG_KMEM
>> +#define ___GFP_KMEMCG		0x400000u
>> +#else
>> +#define ___GFP_KMEMCG		0
>> +#endif
> 
> Could you leave __GFP_MEMCG a simple definition and then define GFP_MEMCG
> to be zer0 if !MEMCG_KMEM? I think that would be cleaner and the
> __GFP_KMEMCHECK another case that would be good to fix up.
> 
> 
> 
I can, but what does this buy us?
Also, in any case, this can be done incrementally, and for the other
flag as well, as you describe.