Re: WARNING: at kernel/rcutree.c:1558 rcu_do_batch+0x386/0x3a0(),during CPU hotplug

From: Srivatsa S. Bhat
Date: Fri Sep 14 2012 - 08:35:09 EST


On 09/14/2012 05:55 PM, Peter Zijlstra wrote:
> On Fri, 2012-09-14 at 17:48 +0530, Srivatsa S. Bhat wrote:
>> #! /bin/bash
>
> CPUPATH="/sys/devices/system/cpu"
>
>> NUMBER_OF_CPUS=`ls -d /sys/devices/system/cpu/cpu[0-9]* | wc -l`
>
> apply the above
>
>> cd /sys/devices/system/cpu
>
> skip this, so running the script doesn't change PWD
>
>> while [ 1 ]
>
> while :;
>
>> do
>> for ((i=1; i < NUMBER_OF_CPUS; i++))
>> do
>> sleep 1;
>
> Also play with shorter sleeps like: sleep .1, I've found that higher
> hotplug rate triggers some races faster.
>
>> state=`cat cpu$i/online`
>> if [ $state -eq 0 ]
>> then
>> echo 1 > cpu$i/online
>> else
>> echo 0 > cpu$i/online
>
> echo $((state^1)) > $CPUPATH/cpu$i/online
>
>> fi
>> done
>> done
>
>

Thanks a lot Peter for your suggestions!

Fengguang, like I had mentioned some time before, somebody had pointed
me to a hotplug test-suite that I believe is being used in LTP.

I have a copy of that suite, which I have attached with this mail.
I have never actually used it seriously before (because I could trigger
bugs with my simple script!), so I don't exactly know what state it is
in ;-)

Regards,
Srivatsa S. Bhat

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