Re: [patch] mm, thp: do not allow thp faults to avoid cpuset restrictions

[Alex Thorlton]

On Wed, Jul 23, 2014 at 03:50:09PM -0700, David Rientjes wrote:
> The page allocator relies on __GFP_WAIT to determine if ALLOC_CPUSET 
> should be set in allocflags.  ALLOC_CPUSET controls if a page allocation 
> should be restricted only to the set of allowed cpuset mems.
> 
> Transparent hugepages clears __GFP_WAIT when defrag is disabled to prevent 
> the fault path from using memory compaction or direct reclaim.  Thus, it 
> is unfairly able to allocate outside of its cpuset mems restriction as a 
> side-effect.
> 
> This patch ensures that ALLOC_CPUSET is only cleared when the gfp mask is 
> truly GFP_ATOMIC by verifying it is also not a thp allocation.

Tested.  Works as expected.

Tested-by: Alex Thorlton <athorlton@xxxxxxx>
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