From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: BUG: soft lockup detected on CPU#0! (2.6.18.2 plus hacks) Date: Mon, 8 Jan 2007 10:03:50 -0800 Message-ID: <20070108100350.1187a3dc@freekitty> References: <20070104.123333.91315611.davem@davemloft.net> <459EB627.5040606@candelatech.com> <20070108065346.GA1665@ff.dom.local> <45A277E6.6000904@candelatech.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Jarek Poplawski , David Miller , herbert@gondor.apana.org.au, dlstevens@us.ibm.com, netdev@vger.kernel.org Return-path: Received: from smtp.osdl.org ([65.172.181.24]:60016 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422697AbXAHSHS (ORCPT ); Mon, 8 Jan 2007 13:07:18 -0500 To: Ben Greear In-Reply-To: <45A277E6.6000904@candelatech.com> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Mon, 08 Jan 2007 08:57:10 -0800 Ben Greear wrote: > Jarek Poplawski wrote: > > On Fri, Jan 05, 2007 at 12:33:43PM -0800, Ben Greear wrote: > > ... > > > >> So, I do believe this was the problem we were hitting, and it seems fixed. > >> > > > > Congratulations! > > > > But I can see one strange thing in vlan.c: > > > > /* Must be invoked with RCU read lock (no preempt) */ > > static struct vlan_group *__vlan_find_group(int real_dev_ifindex) > > ... > > * Must be invoked with RCU read lock (no preempt) > > */ > > struct net_device *__find_vlan_dev(struct net_device *real_dev, > > ... > > > > But later in this file no sign of disabling preemption > > for these calls and for hlist_add_head_rcu and hlist_del_rcu. > > > > I can't imagine how this works? Preempt is already disabled on the receive path. > > > Perhaps...I didn't RCU-ify VLANs, but I can take a look. > > For the record, the soft lockup was using MAC-VLANs, not 802.1Q VLANs, > so it wouldn't > have been affected by bugs in VLANs one way or the other. > > Ben > > > Jarek P. > > > > -- Stephen Hemminger