On Mon, 8 Aug 2011, Torsten Luettgert wrote:

> I recently upgraded one of our KVM servers from SL 6.0 to 6.1. Now
> (yesterday) the machine was under heavy I/O load. I investigated and
> saw that all virtual machines with CentOS 5.6 (we switched to SL just a
> few months ago) are writing hundreds of thousands of these messages
> to /var/log/messages:
>
> Aug  8 13:15:20 infra kernel: : BUG: scheduling while atomic:
> swapper/0xffff0000/0 Aug  8 13:15:20 infra kernel: :
> Aug  8 13:15:20 infra kernel: : Call Trace:
> Aug  8 13:15:20 infra kernel: : [<ffffffff8006243d>]
> __sched_text_start+0x7d/0xbce Aug  8 13:15:20 infra kernel: :
> [<ffffffff8006bdb5>] default_idle+0x0/0x50 Aug  8 13:15:20 infra
> kernel: : [<ffffffff800494dd>] cpu_idle+0xb6/0xb8 Aug  8 13:15:20 infra
> kernel: : [<ffffffff80461807>] start_kernel+0x220/0x225 Aug  8 13:15:20
> infra kernel: : [<ffffffff8046122f>] _sinittext+0x22f/0x236 Aug  8
> 13:15:20 infra kernel: :
>
> Now I'm not sure if this is a problem of the underlying CentOS kernel
> (that one was upgraded on july, 20th) or of SL 6.1 KVM (upgraded
> august, 1st). The SL 6.0/6.1 machines don't show this problem. The
> 5.6 machines didn't under SL 6.0.
>
> Right now I disabled the swap which seems to help, but this can of
> course only be a temporary solution.
>
> I also saw that RH released two minor releases of qemu-kvm that aren't
> yet in SL; would it make sense to try to compile the newest of them and
> update?
>
> If anyone knows something about this problem, any help is greatly
> appreciated.

This seems to be related:

     https://bugzilla.redhat.com/show_bug.cgi?id=725332

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