Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933207Ab2FVVMK (ORCPT ); Fri, 22 Jun 2012 17:12:10 -0400 Received: from mail-yx0-f174.google.com ([209.85.213.174]:63134 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932098Ab2FVVMI (ORCPT ); Fri, 22 Jun 2012 17:12:08 -0400 MIME-Version: 1.0 In-Reply-To: <1340388785.4604.11442.camel@edumazet-glaptop> References: <4FE37783.9000409@akamai.com> <1340310469.4604.6702.camel@edumazet-glaptop> <4FE41570.4090803@akamai.com> <1340353746.4604.9502.camel@edumazet-glaptop> <4FE476A6.1050209@akamai.com> <1340388785.4604.11442.camel@edumazet-glaptop> Date: Fri, 22 Jun 2012 17:12:07 -0400 Message-ID: Subject: Re: Bug in net/ipv6/ip6_fib.c:fib6_dump_table() From: Debabrata Banerjee To: Eric Dumazet Cc: Josh Hunt , "davem@davemloft.net" , "kaber@trash.net" , "netdev@vger.kernel.org" , "yoshfuji@linux-ipv6.org" , "jmorris@namei.org" , "pekkas@netcore.fi" , "kuznet@ms2.inr.ac.ru" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1211 Lines: 26 On Fri, Jun 22, 2012 at 2:13 PM, Eric Dumazet wrote: > On Fri, 2012-06-22 at 08:44 -0500, Josh Hunt wrote: > >> Ahh. That makes sense and is what Alexey said before I just didn't put >> it all together. So we are OK reverting this patch? I cannot find a path >> where the walker's pointers are updated without the tb6_lock write_lock. >> > > There was a bug somewhere, not sure we want to NULL dereference again. > As you identified, the tree seems to be protected by tb6_lock. I couldn't find a race by inspection either. If this is not the root of the problem, how would this patch fix it? So I think it does nothing. We are attempting to reproduce that crash to prove it, but like Gao feng I don't think we will see it. My current favorite theory is that inet6_dump_fib was called with a NULL func in callback. This looks like the approximate area of the crash, but it's impossible to say without more information from Patrick McHardy. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/