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

From: Prarit Bhargava
Date: Fri Nov 01 2013 - 08:08:31 EST

On 11/01/2013 07:36 AM, Rik van Riel wrote:
> On 11/01/2013 07:08 AM, Mel Gorman wrote:
>> On Thu, Oct 31, 2013 at 04:31:44PM -0400, Rik van Riel wrote:
>>> There is a race between stop_two_cpus, and the global stop_cpus.
>> What was the trigger for this? I want to see what was missing from my own
>> testing. I'm going to go out on a limb and guess that CPU hotplug was also
>> running in the background to specifically stress this sort of rare condition.
>> Something like running a standard test with the monitors/
>> from mmtests running in parallel.
> AFAIK the trigger was a test that continuously loads and
> unloads kernel modules, while doing other stuff.

With this patch in place the module load/unload test ran for ~16 hours without
failure. Without the patch the test usually fails in 5-10 minutes.

Tested-by: Prarit Bhargava <prarit@xxxxxxxxxx>

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