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Message-Id: <20070903054959.3ecd9576.akpm@linux-foundation.org>
Date: Mon, 3 Sep 2007 05:49:59 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Jan Kara <jack@...e.cz>
Cc: folkert@...heusden.com, linux-kernel@...r.kernel.org, jack@....cz,
a.p.zijlstra@...llo.nl
Subject: Re: [2.6.22] circular lock detected
> On Mon, 3 Sep 2007 14:27:02 +0200 Jan Kara <jack@...e.cz> wrote:
> > > On Fri, 24 Aug 2007 23:00:33 +0200 Folkert van Heusden <folkert@...heusden.com> wrote:
> > > Hi,
> > >
> > > 2.6.22 kernel with hyperthreading enabled only ext3 filesystems (2).
> > >
> > > [ 346.314640] =======================================================
> > > [ 346.314758] [ INFO: possible circular locking dependency detected ]
> > > [ 346.314815] 2.6.22 #5
> > > [ 346.314862] -------------------------------------------------------
> > > [ 346.314920] tor/2421 is trying to acquire lock:
> > > [ 346.314973] (tty_mutex){--..}, at: [<c121aa83>] mutex_lock+0x8/0xa
> > > [ 346.315193]
> > > [ 346.315195] but task is already holding lock:
> > > [ 346.316203] (&s->s_dquot.dqptr_sem){----}, at: [<c10a485f>] dquot_alloc_space+0x50/0x189
> > > [ 346.316457]
> > > [ 346.316458] which lock already depends on the new lock.
>
> ...
>
> > > [ 346.353603] =======================
> > >
> > Has been reported before, but I don't recall whether we fixed it. Jan,
> > do you know>?
> I think we at least found a solution: Teach lockdep that I_MUTEX for
> different filesystems is different. Peter Zilstra wrote a patch for that
> and Folkert even confirmed that it fixes the problem for him. I'm not
> sure what happened with the patch afterwards though. Adding Peter to CC
> :).
But this is a tty_lock-versus-dqptr_sem ranking error. Unrelated to i_mutex?
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