linux-kernel - Re: [PATCH] mm: Fix kswapd livelock on single core, no preempt kernel

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Message-ID: <CAGTjWtByuv2Z+7rydJzdydrQmxiE5ErHH8OaX6fhOg5eS6X9OQ@mail.gmail.com>
Date:	Wed, 14 Dec 2011 07:37:22 -0800
From:	Mike Waychison <mikew@...gle.com>
To:	Mel Gorman <mgorman@...e.de>
Cc:	Shaohua Li <shaohua.li@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Minchan Kim <minchan.kim@...il.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Johannes Weiner <jweiner@...hat.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Hugh Dickens <hughd@...gle.com>,
	Greg Thelen <gthelen@...gle.com>
Subject: Re: [PATCH] mm: Fix kswapd livelock on single core, no preempt kernel

On Wed, Dec 14, 2011 at 4:20 AM, Mel Gorman <mgorman@...e.de> wrote:
> On Tue, Dec 13, 2011 at 08:36:43PM -0800, Mike Waychison wrote:
>> FYI, this was seen with a 2.6.39-based kernel with no-numa, no-memcg
>> and swap-enabled.
>>
>
> If this is 2.6.39, can you try applying the commit
> [f06590bd: mm: vmscan: correctly check if reclaimer should schedule during shrink_slab]
>
> There have been a few fixes around kswapd hogging the CPU since 2.6.39.

In this particular case, I didn't see any problem acquiring
shrinker_rwsem (the shrinkers should up in the cpu profile I
gathered).  I think this patch would fix my issue though as it happens
to drop in a cond_resched() into the path.  It isn't obvious that this
cond_resched() really belongs in shrink_slab() though.  Thanks :)

>
> --
> Mel Gorman
> SUSE Labs
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