linux-kernel - Re: BUG or virtualbox issue?

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Date:	Fri, 26 Dec 2008 14:42:03 -0500
From:	Rik van Riel <riel@...hat.com>
To:	Udo van den Heuvel <udovdh@...all.nl>
CC:	linux-kernel@...r.kernel.org
Subject: Re: BUG or virtualbox issue?

Udo van den Heuvel wrote:
> Hello,
> 
> Just started virtualbox for the first time on x86_64 Phenom system; is 
> this a kernel issue or something for the VirtualBox people?
> 
> Dec 26 12:20:01 surfplank2 kernel: BUG: using smp_processor_id() in 
> preemptible [00000000] code: VirtualBox/26774
> Dec 26 12:20:01 surfplank2 kernel: caller is RTMpCpuId+0x9/0x10 [vboxdrv]
> Dec 26 12:20:01 surfplank2 kernel: Pid: 26774, comm: VirtualBox Not 
> tainted 2.6.28 #3

Looks like the virtualbox code forgot to switch off
preemption before calling smp_processor_id().

This is broken, because the thread could get de-scheduled
and re-scheduled onto another CPU, which means the code
could end up using the wrong smp processor ID.

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