linux-kernel - Re: [RFC 06/13] mm, thp: remove __GFP_NORETRY from khugepaged and madvised allocations

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Message-ID: <20160512162043.GA4261@dhcp22.suse.cz>
Date:	Thu, 12 May 2016 18:20:45 +0200
From:	Michal Hocko <mhocko@...nel.org>
To:	Vlastimil Babka <vbabka@...e.cz>
Cc:	linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Rik van Riel <riel@...hat.com>,
	David Rientjes <rientjes@...gle.com>,
	Mel Gorman <mgorman@...hsingularity.net>,
	Johannes Weiner <hannes@...xchg.org>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [RFC 06/13] mm, thp: remove __GFP_NORETRY from khugepaged and
 madvised allocations

On Tue 10-05-16 09:35:56, Vlastimil Babka wrote:
[...]
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index 570383a41853..0cb09714d960 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -256,8 +256,7 @@ struct vm_area_struct;
>  #define GFP_HIGHUSER	(GFP_USER | __GFP_HIGHMEM)
>  #define GFP_HIGHUSER_MOVABLE	(GFP_HIGHUSER | __GFP_MOVABLE)
>  #define GFP_TRANSHUGE	((GFP_HIGHUSER_MOVABLE | __GFP_COMP | \
> -			 __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN) & \
> -			 ~__GFP_RECLAIM)
> +			 __GFP_NOMEMALLOC | __GFP_NOWARN) & ~__GFP_RECLAIM)

I am not sure this is the right thing to do. I think we should keep
__GFP_NORETRY and clear it where we want a stronger semantic. This is
just too suble that all callsites are doing the right thing.
-- 
Michal Hocko
SUSE Labs