From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [bug] __nf_ct_refresh_acct(): WARNING: at lib/list_debug.c:30 __list_add+0x7d/0xad() Date: Wed, 17 Jun 2009 17:29:11 +0200 Message-ID: <4A390BC7.3030901@gmail.com> References: <20090615.050449.144947903.davem@davemloft.net> <20090616091538.GA4184@elte.hu> <20090616.034752.226811527.davem@davemloft.net> <20090616105304.GA3579@elte.hu> <20090616122415.GA16630@elte.hu> <20090617092152.GA17449@elte.hu> <4A38C2F3.3000009@gmail.com> <4A38D5BD.2040502@trash.net> <4A38D9BE.3020403@gmail.com> <4A38DAC4.2050902@trash.net> <4A38E2AE.3030106@gmail.com> <4A38E33E.1050006@trash.net> <4A38EF40.7040106@gmail.com> <4A38EFC4.8000907@trash.net> <4A38FC5A.70500@trash.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Ingo Molnar , David Miller , Thomas Gleixner , torvalds@linux-foundation.org, akpm@linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Patrick McHardy Return-path: Received: from gw1.cosmosbay.com ([212.99.114.194]:46898 "EHLO gw1.cosmosbay.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754753AbZFQP31 (ORCPT ); Wed, 17 Jun 2009 11:29:27 -0400 In-Reply-To: <4A38FC5A.70500@trash.net> Sender: netdev-owner@vger.kernel.org List-ID: Patrick McHardy a =E9crit : > Patrick McHardy wrote: >> Eric Dumazet wrote: >>> Patrick McHardy a =E9crit : >>>> No, before it is confirmed, its only visible to the CPU handling >>>> the initial packet of a connection. Confirmation is the step that >>>> makes it visible to other CPUs. >>> >>> Thanks Patrick, I missed this, and your patch seems fine now :) >> >> Thanks for your help, I'll send it to Dave later today. >=20 > I'm having some trouble figuring out the exact events that would > lead to the timer base corruption. Ingo, could you please test > this patch to make sure it also fixes the problem? >=20 >=20 ;) Event can be described as following : CPU1 CPU2 /* __nf_conntrack_confirm() */ __nf_conntrack_hash_insert(ct, hash, repl_hash); // now 'ct' is visible by other cpus // search conntrack and find ct // timeout.expires becomes absolute here ct->timeout.expires +=3D jiffies; add_timer(&ct->timeout); /* __nf_ct_refresh_acct() */ if (!nf_ct_is_confirmed(ct)) { // we *believe* timeout.expires=20 // is not yet in use by timer code // and is still a relative quantity. // We want to 'update' it but we should not ! ct->timeout.expires =3D extra_jiffies; << CORRUPTION >> } else { // too late :( set_bit(IPS_CONFIRMED_BIT, &ct->status); This is how I understood the problem, but I may be wrong ?