From owner-freebsd-current@FreeBSD.ORG Mon Jun 29 15:14:04 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 4C29E106564A for ; Mon, 29 Jun 2009 15:14:04 +0000 (UTC) (envelope-from lstewart@freebsd.org) Received: from lauren.room52.net (lauren.room52.net [210.50.193.198]) by mx1.freebsd.org (Postfix) with ESMTP id D3CA68FC1C for ; Mon, 29 Jun 2009 15:14:03 +0000 (UTC) (envelope-from lstewart@freebsd.org) Received: from lstewart-laptop.caia.swin.edu.au (c149.al.cl.cam.ac.uk [128.232.110.149]) (authenticated bits=0) by lauren.room52.net (8.14.3/8.14.3) with ESMTP id n5TFDsbg052301 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 30 Jun 2009 01:13:56 +1000 (EST) (envelope-from lstewart@freebsd.org) Message-ID: <4A48DA31.5010900@freebsd.org> Date: Mon, 29 Jun 2009 16:13:53 +0100 From: Lawrence Stewart User-Agent: Thunderbird 2.0.0.22 (X11/20090626) MIME-Version: 1.0 To: Kamigishi Rei References: <4A45ABB1.7040506@haruhiism.net> <4A48CE02.5000200@freebsd.org> <4A48D4A2.8010207@haruhiism.net> In-Reply-To: <4A48D4A2.8010207@haruhiism.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,SPF_SOFTFAIL autolearn=disabled version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on lauren.room52.net Cc: freebsd-current@freebsd.org Subject: Re: r194546 amd64: kernel panic in tcp_sack.c X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 29 Jun 2009 15:14:04 -0000 Kamigishi Rei wrote: > Lawrence Stewart wrote: >> I'm not intimately familiar with our SACK implementation, and these >> things are often extremely painful to track down. First step: is the >> panic reproducible? > So far I couldn't reproduce it, but I think the fact that I couldn't > reproduce it has something to do with frequent reboots due to > buildworld/buildkernel lately because of other problems. Ok. I'm working on a patch to address a different TCP/SACK issue, but it may in fact be partially relevant to the cause of your panic... can't promise when I'll be able to take a close look at this but I'm aware of it now so that's a start. If you run into it again or find the trigger for the panic, please let me know. >> How did you try to get it to save the core? A dump would be very >> useful to have around. > Since I'm not much of an expert in the kernel debugger, I tried to let > it continue with the panic, i.e. typed 'continue' which produced a fatal > trap 12 right after "Dumping XXXX MB: (~3 values were here)". Next time from the ddb prompt, try typing "call doadump" instead of "continue". That will hopefully get you a usable core dump which would be handy. After it finishes dumping the core type "reset" to reboot the machine. Cheers, Lawrence