linux-kernel - Re: [PATCH -v2 -tip] fix race between stop_two_cpus and stop

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Message-ID: <20131101144728.GY2400@suse.de>
Date:	Fri, 1 Nov 2013 14:47:28 +0000
From:	Mel Gorman <mgorman@...e.de>
To:	Rik van Riel <riel@...hat.com>
Cc:	Peter Zijlstra <peterz@...radead.org>, mingo@...nel.org,
	prarit@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -v2 -tip] fix race between stop_two_cpus and stop_cpus

On Fri, Nov 01, 2013 at 10:41:46AM -0400, Rik van Riel wrote:
> Subject: fix race between stop_two_cpus and stop_cpus
> 
> There is a race between stop_two_cpus, and the global stop_cpus.
> 
> It is possible for two CPUs to get their stopper functions queued
> "backwards" from one another, resulting in the stopper threads
> getting stuck, and the system hanging. This can happen because
> queuing up stoppers is not synchronized.
> 
> This patch adds synchronization between stop_cpus (a rare operation),
> and stop_two_cpus.
> 
> Signed-off-by: Rik van Riel <riel@...hat.com>
> ---
> v2: use lglock, as suggested by Peter & Mel, thanks to both of you
> for insisting on nicer code :)
> 

This is a tad more comprehensible :). Thanks!

Acked-by: Mel Gorman <mgorman@...e.de>

-- 
Mel Gorman
SUSE Labs
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