linux-kernel - Re: [PATCH 0.14] oom detection rework v6

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Message-ID: <20160504085004.GC29978@dhcp22.suse.cz>
Date:	Wed, 4 May 2016 10:50:04 +0200
From:	Michal Hocko <mhocko@...nel.org>
To:	Vlastimil Babka <vbabka@...e.cz>
Cc:	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Mel Gorman <mgorman@...e.de>,
	David Rientjes <rientjes@...gle.com>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	Hillf Danton <hillf.zj@...baba-inc.com>, linux-mm@...ck.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0.14] oom detection rework v6

On Wed 04-05-16 10:12:43, Vlastimil Babka wrote:
> On 05/04/2016 07:45 AM, Joonsoo Kim wrote:
> >I still don't agree with some part of this patchset that deal with
> >!costly order. As you know, there was two regression reports from Hugh
> >and Aaron and you fixed them by ensuring to trigger compaction. I
> >think that these show the problem of this patchset. Previous kernel
> >doesn't need to ensure to trigger compaction and just works fine in
> >any case.
> 
> IIRC previous kernel somehow subtly never OOM'd for !costly orders. So
> anything that introduces the possibility of OOM may look like regression for
> some corner case workloads.

The bug fixed by this series was COMPACTION specific because
compaction_ready is not considered otherwise.
-- 
Michal Hocko
SUSE Labs