From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Greear Subject: Re: [BUG, NET] deadlock tearing down a bridged interface Date: Sat, 19 Jul 2008 10:01:35 -0700 Message-ID: <48821DEF.1040306@candelatech.com> References: <20080718073724.GA5802@disturbed> <4880BA7A.3020909@candelatech.com> <20080719011709.GA5947@disturbed> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: Ben Greear , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Return-path: Received: from mail.candelatech.com ([208.74.158.172]:57777 "EHLO ns3.lanforge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750989AbYGSRBl (ORCPT ); Sat, 19 Jul 2008 13:01:41 -0400 In-Reply-To: <20080719011709.GA5947@disturbed> Sender: netdev-owner@vger.kernel.org List-ID: Dave Chinner wrote: > On Fri, Jul 18, 2008 at 08:44:58AM -0700, Ben Greear wrote: > >> Dave Chinner wrote: >> >>> Folks, >>> >>> I just deadlocked networking on a 2.6.24 kernel. Basically I >>> was trying to restart the bridge interface I use for UML sessions >>> because it wasn't passing packets. This happens occasionally >>> when I leave a UML session too long in gdb, so I bounced the >>> bridge to get it working again. >>> >>> >> We have been chasing a refcount bug in 2.6.25 that only happens when >> IPv6 module is loaded. >> > > Which causes what problem? The deadlock I reported or the bridge occasionally > hanging? Is that a problem in 2.6.24? > > The deadlock is the one I'm concerned about - it appears that > netdev_run_todo() can only wait on a single interface at a time, > so if we are tearing down two interfaces concurrently where one > has a reference on the other a deadlock is just waiting to happen... > Our problem is the refcount hang while trying to remove a netdevice. It appears to be an ipv6 related leakage of some sort, and not directly related to bridges. Thanks, Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com