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Subject: Re: 2.6.29-rc3: BUG: scheduling while atomic: udevd/917/0x10000100
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Ingo Molnar <mingo@elte.hu>
Cc: Vegard Nossum <vegard.nossum@gmail.com>,
       Alexey Dobriyan <adobriyan@gmail.com>,
       Andrew Morton <akpm@linux-foundation.org>, Greg KH <gregkh@suse.de>,
       LKML <linux-kernel@vger.kernel.org>
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Date: Wed, 11 Feb 2009 09:49:49 +0100
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On Wed, 2009-02-11 at 09:32 +0100, Ingo Molnar wrote:

> There's a fourth possibility:
> 
>  - Given that it's udevd that does it - maybe we leaked a softirq preempt
>    count in some rare sysfs file, and it did not get discovered until the
>    next innocent piece of kernel code preempted?
> 
> But i thought lockdep would already warn if we exited a syscall with locks
> held or with a preempt count elevated - Peter?

>>From a quick look it only checks task->lockdep_depth, in
lockdep_sys_exit().