From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarek Poplawski Subject: Re: BUG: soft lockup detected on CPU#0! (2.6.18.2 plus hacks) Date: Thu, 11 Jan 2007 09:35:26 +0100 Message-ID: <20070111083526.GC1672@ff.dom.local> References: <20070110125048.GB2611@ff.dom.local> <20070110120123.52376578@freekitty> <20070111072428.GA1672@ff.dom.local> <20070110.234035.102123688.davem@davemloft.net> <20070111082958.GB1672@ff.dom.local> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: shemminger@osdl.org, greearb@candelatech.com, herbert@gondor.apana.org.au, dlstevens@us.ibm.com, netdev@vger.kernel.org Return-path: Received: from mx2.go2.pl ([193.17.41.42]:44255 "EHLO poczta.o2.pl" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1030226AbXAKIdb (ORCPT ); Thu, 11 Jan 2007 03:33:31 -0500 To: David Miller Content-Disposition: inline In-Reply-To: <20070111082958.GB1672@ff.dom.local> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, Jan 11, 2007 at 09:29:58AM +0100, Jarek Poplawski wrote: > On Wed, Jan 10, 2007 at 11:40:35PM -0800, David Miller wrote: > > From: Jarek Poplawski > > Date: Thu, 11 Jan 2007 08:24:28 +0100 > > > > > Yesterday I did what I should do earlier - checked > > > this simple way, with printk, and now I have no doubts > > > it's a bug: if you add or remove vlan devices with > > > vconfig, register_vlan_device and unregister_vlan_dev > > > are called by ioctl and they use and change rcu > > > procetded data without preemption disabled so vlan > > > rcu hash lists could become corrupted or find results > > > could be wrong. > > > > Those two operations do their modifications and changes under the RTNL > > semaphore, via rtnl_lock() and rtnl_unlock() which guarentees that no > > other modifications can occur. > > Sure, but is this even legal to be preempted during I should even say: "... is this even legal to be blocked during ..." > reading or modifying rcu list? Doesn't this disturb > rcu cycle and make possible memory release problems? Jarek P.