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Date: Wed, 4 May 2016 10:50:04 +0200
From: Michal Hocko <mhocko@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>, Mel Gorman <mgorman@suse.de>,
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        Hillf Danton <hillf.zj@alibaba-inc.com>, linux-mm@kvack.org,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0.14] oom detection rework v6
Message-ID: <20160504085004.GC29978@dhcp22.suse.cz>
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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