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Date: Thu, 29 May 2014 16:12:53 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: David Rientjes <rientjes@google.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>, Li Zefan <lizefan@huawei.com>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Lai Jiangshan <laijs@cn.fujitsu.com>, Mel Gorman <mgorman@suse.de>,
        Tejun Heo <tj@kernel.org>, Christoph Lameter <cl@linux.com>
Subject: Re: [PATCH] page_alloc: skip cpuset enforcement for lower zone
 allocations (v4)
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On Thu, 29 May 2014 16:01:55 -0700 (PDT) David Rientjes <rientjes@google.com> wrote:

> There are still three issues with this, two of which are only minor and 
> one that needs more thought:
> 
>  (1) this doesn't affect only cpusets which the changelog indicates, it 
>      also bypasses mempolicies for GFP_DMA and GFP_DMA32 allocations since
>      the nodemask != NULL in the page allocator when there is an effective
>      mempolicy.  That may be precisely what you're trying to do (do the
>      same for mempolicies as you're doing for cpusets), but the comment 
>      now in the code specifically refers to cpusets.  Can you make a case
>      for the mempolicies exception as well?  Otherwise, we'll need to do
> 
> 	if (!nodemask && gfp_zone(gfp_mask) < policy_zone)
> 		nodemask = &node_states[N_ONLINE];
> 
> And the two minors:
> 
>  (2) this should be &node_states[N_MEMORY], not &node_states[N_ONLINE] 
>      since memoryless nodes should not be included.  Note that
>      guarantee_online_mems() looks at N_MEMORY and
>      cpuset_current_mems_allowed is defined for N_MEMORY without
>      cpusets.
> 
>  (3) it's unnecessary for this to be after the "retry_cpuset" label and
>      check the gfp mask again if we need to relook at the allowed cpuset
>      mask.

OK, thanks, I made the patch go away for now.