From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753507Ab0ECFlT (ORCPT ); Mon, 3 May 2010 01:41:19 -0400 Received: from mail-bw0-f219.google.com ([209.85.218.219]:33730 "EHLO mail-bw0-f219.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752348Ab0ECFlP (ORCPT ); Mon, 3 May 2010 01:41:15 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=SH/l4FVcbT5wtj8o1nKqvCBCOGKT1csJtX2nh8R8bY87P20ZFgdi0m+AXadKZAdoBp yT9iZDn4OnHIjYVliKmnophdV4LnGE2bz4uGxAJr9cgxlRginXeTA30bldXpLQbxQKId pv//OUlWQOixGpV0tMbJBibtuZKsMNDbGUFY4= Subject: Re: mmotm 2010-04-28 - RCU whinges From: Eric Dumazet To: Valdis.Kletnieks@vt.edu Cc: Andrew Morton , Peter Zijlstra , Patrick McHardy , "David S. Miller" , linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org, netdev@vger.kernel.org, "Paul E. McKenney" In-Reply-To: <1272865137.2173.179.camel@edumazet-laptop> References: <201004290021.o3T0L04Y028017@imap1.linux-foundation.org> <5702.1272822394@localhost> <1272865137.2173.179.camel@edumazet-laptop> Content-Type: text/plain; charset="UTF-8" Date: Mon, 03 May 2010 07:41:07 +0200 Message-ID: <1272865267.2173.180.camel@edumazet-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le lundi 03 mai 2010 à 07:38 +0200, Eric Dumazet a écrit : > Le dimanche 02 mai 2010 à 13:46 -0400, Valdis.Kletnieks@vt.edu a écrit : > > On Wed, 28 Apr 2010 16:53:32 PDT, akpm@linux-foundation.org said: > > > The mm-of-the-moment snapshot 2010-04-28-16-53 has been uploaded to > > > > > > http://userweb.kernel.org/~akpm/mmotm/ > > > > I thought we swatted all these, hit another one... > > > > [ 9.131490] ctnetlink v0.93: registering with nfnetlink. > > [ 9.131535] > > [ 9.131535] =================================================== > > [ 9.131704] [ INFO: suspicious rcu_dereference_check() usage. ] > > [ 9.131794] --------------------------------------------------- > > [ 9.131883] net/netfilter/nf_conntrack_ecache.c:88 invoked rcu_dereference_check() without protection! > > [ 9.131977] > > [ 9.131977] other info that might help us debug this: > > [ 9.131978] > > [ 9.132218] > > [ 9.132219] rcu_scheduler_active = 1, debug_locks = 0 > > [ 9.132434] 1 lock held by swapper/1: > > [ 9.132519] #0: (nf_ct_ecache_mutex){+.+...}, at: [] nf_conntrack_register_notifier+0x1a/0x75 > > [ 9.132938] > > [ 9.132939] stack backtrace: > > [ 9.133129] Pid: 1, comm: swapper Tainted: G W 2.6.34-rc5-mmotm0428 #1 > > [ 9.133220] Call Trace: > > [ 9.133319] [] lockdep_rcu_dereference+0xaa/0xb2 > > [ 9.133410] [] nf_conntrack_register_notifier+0x3d/0x75 > > [ 9.133521] [] ctnetlink_init+0x71/0xd5 > > [ 9.133627] [] ? ctnetlink_init+0x0/0xd5 > > [ 9.133735] [] do_one_initcall+0x59/0x14e > > [ 9.133843] [] kernel_init+0x144/0x1ce > > [ 9.133949] [] kernel_thread_helper+0x4/0x10 > > [ 9.134060] [] ? restore_args+0x0/0x30 > > [ 9.134196] [] ? kernel_init+0x0/0x1ce > > [ 9.134328] [] ? kernel_thread_helper+0x0/0x10 > > [ 9.134530] ip_tables: (C) 2000-2006 Netfilter Core Team > > [ 9.134655] TCP bic registered > > > > Thanks for the report ! > > We can use rcu_dereference_protected() in those cases. > > [PATCH] net: Use rcu_dereference_protected in nf_conntrack_ecache > > Writers own nf_ct_ecache_mutex. > > Reported-by: Valdis Kletnieks > Signed-off-by: Eric Dumazet > --- Oops scratch that, I'll resend a correct version.