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Date: Tue, 16 Oct 2007 02:08:26 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Alexey Dobriyan <adobriyan@sw.ru>, linux-kernel@vger.kernel.org,
       mingo@elte.hu
Subject: Re: Possible circular locking: ->mmap_sem vs jbd_handle
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On Tue, 16 Oct 2007 11:05:12 +0200 Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:

> On Tue, 2007-10-16 at 02:01 -0700, Andrew Morton wrote:
> > On Tue, 16 Oct 2007 12:54:29 +0400 Alexey Dobriyan <adobriyan@sw.ru> wrote:
> > 
> > > Got this during LTP's diotest1. Reproducable.
> > > 
> > > =======================================================
> > > [ INFO: possible circular locking dependency detected ]
> > > 2.6.23-65a6ec0d72a07f16719e9b7a96e1c4bae044b591 #2
> > > -------------------------------------------------------
> > > diotest1/13563 is trying to acquire lock:
> > >  (&mm->mmap_sem){----}, at: [<c107a7b7>] dio_get_page+0x4b/0x16b
> > > 
> > > but task is already holding lock:
> > >  (jbd_handle){--..}, at: [<c1099b05>] journal_start+0xf3/0x120
> > > 
> > > which lock already depends on the new lock.
> > 
> > Someone taught lockdep about journal_start?  That's gonna hurt.
> 
> It was you who suggested doing so,...

yeah, but I didn't think anyone would go and do it!

> Are these valid reports, or is the annotation wrong?

It's valid.  There will be others..

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