Date: Wed, 7 Jan 2009 14:06:46 -0800
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Eric Sesterhenn <snakebyte@gmx.de>
Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
       linux-kernel@vger.kernel.org, josh@freedesktop.org, dipankar@in.ibm.com
Subject: Re: [BUG] NULL pointer deref with rcutorture
Message-ID: <20090107220646.GH6900@linux.vnet.ibm.com>
Reply-To: paulmck@linux.vnet.ibm.com
References: <20090105200012.GB11244@alice> <20090105201631.GO6959@linux.vnet.ibm.com> <20090105203153.GC11244@alice> <20090105221836.GT6959@linux.vnet.ibm.com> <20090106002912.GA21071@linux.vnet.ibm.com> <20090106021506.GA23052@linux.vnet.ibm.com> <20090106074707.GA5975@alice> <20090106124809.GC7655@linux.vnet.ibm.com> <20090107194635.GA17174@linux.vnet.ibm.com> <20090107201904.GA32513@alice>
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On Wed, Jan 07, 2009 at 09:19:04PM +0100, Eric Sesterhenn wrote:
> * Paul E. McKenney (paulmck@linux.vnet.ibm.com) wrote:
> > On Tue, Jan 06, 2009 at 04:48:09AM -0800, Paul E. McKenney wrote:
> > > On Tue, Jan 06, 2009 at 08:47:07AM +0100, Eric Sesterhenn wrote:
> > > > * Paul E. McKenney (paulmck@linux.vnet.ibm.com) wrote:
> > > > > On Mon, Jan 05, 2009 at 04:29:12PM -0800, Paul E. McKenney wrote:
> > > > > > On Mon, Jan 05, 2009 at 02:18:36PM -0800, Paul E. McKenney wrote:
> > > > > > I will see what I can find from this.
> > > > > 
> > > > > Hello, Eric,
> > > > > 
> > > > > Just for grins, I built the 2.6.28 kernel/rcutorture.c on b58602a.  It
> > > > > insmoded and rmmoded without errors.
> > > > > 
> > > > > Could you please try this on your setup?  I have attached this file in
> > > > > case that helps.
> > > > 
> > > > works like a charm
> > > 
> > > Well, that certainly tells me where the bug lies.  ;-)
> > > 
> > > Thank you for all your hard work on this, I should have a patch soon.
> > 
> > And here it is, against the original version of rcutorture.c (revert
> > all of my previous patches against rcutorture.c).  I am also attaching
> > the resulting rcutorture.c, if that makes things more convenient for you.
> > 
> > Could you please fire this up and see if it fixes the rmmod-time bug
> > that you located?
> 
> it does fix the bug, thanks for your work

Thank you very much for finding this one, bearing with me during the
debug process, and testing it!  I will post the patch with credit to you.

Does this fix all of the problems that you observed, or is there still
some breakage?

							Thanx, Paul
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