From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Chapman Subject: Re: [PATCH][PPPOL2TP]: Fix SMP oops in pppol2tp driver Date: Tue, 19 Feb 2008 09:09:38 +0000 Message-ID: <47BA9CD2.5030507@katalix.com> References: <47B0C9F7.5040200@katalix.com> <20080211224924.GA2863@ami.dom.local> <47B0DD1E.5000608@katalix.com> <20080211.213048.192442721.davem@davemloft.net> <47B17BCD.2070903@katalix.com> <20080214130016.GA2583@ff.dom.local> <47BA0214.40703@katalix.com> <20080218230154.GB6373@ami.dom.local> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: David Miller , netdev@vger.kernel.org To: Jarek Poplawski Return-path: Received: from s36.avahost.net ([74.53.95.194]:37519 "EHLO s36.avahost.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760616AbYBSJJo (ORCPT ); Tue, 19 Feb 2008 04:09:44 -0500 In-Reply-To: <20080218230154.GB6373@ami.dom.local> Sender: netdev-owner@vger.kernel.org List-ID: Jarek Poplawski wrote: > On Mon, Feb 18, 2008 at 10:09:24PM +0000, James Chapman wrote: >> Jarek Poplawski wrote: >>> Hi, >>> >>> It seems, this nice report is still uncomplete: could you check if >>> there could have been something more yet? >> Unfortunately the ISP's syslog stops. But I've been able to borrow two >> Quad Xeon boxes and have reproduced the problem. >> >> Here's a new version of the patch. The patch avoids disabling irqs and >> fixes the sk_dst_get() usage that DaveM mentioned. But even with this >> patch, lockdep still complains if hundreds of ppp sessions are inserted >> into a tunnel as rapidly as possible (lockdep trace is below). I can >> stop these errors by wrapping the call to ppp_input() in >> pppol2tp_recv_dequeue_skb() with local_irq_save/restore. What is a >> better fix? > > Hmm... This is a really long report and quite a bit different from > the previous one. I need some time for this. BTW: you sent before a > lockdep report with hlist_lock problem. I think this could be fixed > in some independent patch to make this all more readable. Are all > the other changes in this current patch only because of this or > previous lockdep report or for some other reasons (or reports) yet? As I mentioned in my reply to davem, modifying the pppol2tp driver as described in the patch I sent made the original lockdep problems go away. -- James Chapman Katalix Systems Ltd http://www.katalix.com Catalysts for your Embedded Linux software development