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Date: Wed, 20 May 2009 15:55:37 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>, Zdenek Kabelac <zdenek.kabelac@gmail.com>,
       "Rafael J. Wysocki" <rjw@sisk.pl>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: INFO: possible circular locking dependency at
	cleanup_workqueue_thread
Message-ID: <20090520135537.GA18480@redhat.com>
References: <c4e36d110905120059i4c155508oa00672da0b33a07a@mail.gmail.com> <20090517071834.GA8507@elte.hu> <1242821938.26820.586.camel@twins> <20090520131823.GA14933@redhat.com> <1242827092.26820.612.camel@twins>
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On 05/20, Peter Zijlstra wrote:
>
> On Wed, 2009-05-20 at 15:18 +0200, Oleg Nesterov wrote:
> > On 05/20, Peter Zijlstra wrote:
> > >
> > > Breaking the setup_lock -> cpu_add_remove_lock dependency seems
> > > sufficient.
> >
> > Hmm. What do you mean? Afaics setup_lock -> cpu_add_remove_lock
> > is not a problem?
>
> >From what I could see that is the only dependency that makes
> cpu_add_remove_lock nest under "events" workqueue 'lock', which is what
> is generating the deadlock.

But cpu_add_remove_lock does not participate in this deadlock, see
http://marc.info/?l=linux-kernel&m=124274977707363 ?

Perhaps you mean something else, could you spell in that case?

Oleg.