Re: [PATCH -v2 -tip] fix race between stop_two_cpus and stop_cpus

[Prarit Bhargava]

On 11/01/2013 10:47 AM, Mel Gorman wrote:
> 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@xxxxxxxxxx>
>> ---
>> 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@xxxxxxx>
> 

This ran all morning without issues.

Tested-by: Prarit Bhargava <prarit@xxxxxxxxxx>

P.
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