Date: Mon, 29 Jun 2009 16:13:53 +0100 From: Lawrence Stewart <lstewart@freebsd.org> To: Kamigishi Rei <spambox@haruhiism.net> Cc: freebsd-current@freebsd.org Subject: Re: r194546 amd64: kernel panic in tcp_sack.c Message-ID: <4A48DA31.5010900@freebsd.org> In-Reply-To: <4A48D4A2.8010207@haruhiism.net> References: <4A45ABB1.7040506@haruhiism.net> <4A48CE02.5000200@freebsd.org> <4A48D4A2.8010207@haruhiism.net>
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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, Lawrencehelp
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