Re: [RFC 4/4] mm: Ignore cpuset enforcement when allocation flag has __GFP_THISNODE

[Dave Hansen]

On 11/22/2016 06:19 AM, Anshuman Khandual wrote:
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3715,7 +3715,7 @@ struct page *
>  		.migratetype = gfpflags_to_migratetype(gfp_mask),
>  	};
>  
> -	if (cpusets_enabled()) {
> +	if (cpusets_enabled() && !(alloc_mask & __GFP_THISNODE)) {
>  		alloc_mask |= __GFP_HARDWALL;
>  		alloc_flags |= ALLOC_CPUSET;
>  		if (!ac.nodemask)

This means now that any __GFP_THISNODE allocation can "escape" the
cpuset.  That seems like a pretty major change to how cpusets works.  Do
we know that *ALL* __GFP_THISNODE allocations are truly lacking in a
cpuset context that can be enforced?