From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752062AbaEVHOb (ORCPT ); Thu, 22 May 2014 03:14:31 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:53753 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750931AbaEVHOa (ORCPT ); Thu, 22 May 2014 03:14:30 -0400 Date: Thu, 22 May 2014 16:14:27 +0900 From: Greg Kroah-Hartmann To: Guenter Roeck Cc: Francesco Ruggeri , Hannes Reinecke , linux-kernel@vger.kernel.org Subject: Re: pci: kernel crash in bus_find_device Message-ID: <20140522071427.GA21230@kroah.com> References: <20140520195041.GA28913@roeck-us.net> <20140520233812.GA15640@roeck-us.net> <20140521193010.GA1721@roeck-us.net> <20140521225958.GB2467@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140521225958.GB2467@roeck-us.net> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 21, 2014 at 03:59:58PM -0700, Guenter Roeck wrote: > On Wed, May 21, 2014 at 01:04:04PM -0700, Francesco Ruggeri wrote: > > I have been using an x86 platform. > > When I started working on it I got early crashes until I added the > > check for p not NULL in > > > > +void bus_release_device(struct device *dev) > > +{ > > + struct device_private *p = dev->p; > > + > > + if (p && klist_node_attached(&p->knode_bus)) > > + klist_put_last(&p->knode_bus); > > +} > > + > > > > Maybe on powerpc *p is overriden between device_del and device_release? > > > > Or maybe some of the BUG_ONs in the patch? The ones on knode_dead are > > treated as WARN_ONs in the current klist code. > > The one in BUG_ON(!klist_dec_and_del(n)); is new, and in my tests I > > ran into it without the second patch (but only when I ran my module > > and tests). > > > Hi Francesco, > > I replaced the BUG_ON with WARN_ON; still crashes. > > Anyway, the problem seems to be known. I found two related exchanges. > > [1] describes pretty much the same problem. I don't see if/where it was > ever fixed, though. > > [2] is a patch to fix the problem. It did not apply cleanly to 3.14, > so I had to make some adjustments in klist_iter_init_node. Resulting > patch is below. With this patch, the problem is gone. It is not perfect, > as it aborts the loop if it encounters a deleted kobject, but it is better > than nothing. Unfortunately, the patch never made it upstream; no idea why. > Copying the author and Greg to get additional feedback. > > Guenter > > [1] https://lkml.org/lkml/2008/10/26/79 > [2] https://lkml.org/lkml/2012/4/16/218 2 years ago? I have no idea what was up with that, sorry... greg k-h