Date: Sat, 22 Aug 2015 08:57:40 -0400 (EDT) From: Rick Macklem <rmacklem@uoguelph.ca> To: Joel Dahl <joel@vnode.se>, sbruno@freebsd.org Cc: current@freebsd.org Subject: Re: Kernel panic with fresh current, probably nfs related Message-ID: <914810061.28949434.1440248260373.JavaMail.zimbra@uoguelph.ca> In-Reply-To: <20150822115519.GA79434@ymer.vnode.se> References: <20150822115519.GA79434@ymer.vnode.se>
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Joel Dahl wrote: > Hi, > > I hit a kernel panic running a fresh -CURRENT today. This machine is my home > NFS > server and it exports src and obj to a bunch of other machines. During an > installkernel on one of the other machines (using the src and obj exports > from > the NFS server) the NFS server kernel paniced. > > I took a quick photo of the stack backtrace, since I didn't have time to > investigate further (but I haven't rebooted the machine yet, it's still > sitting at the db> prompt: > > http://mirror.vnode.se/upload/panic001-20150822.JPG > > Any ideas? > I'm going to guess that you're using an "em" net driver, since that is the only one that sets if_hw_tsomax > IP_MAXPACKET (65535) from what I can see. Sean, EM_TSO_SIZE is defined as (65535 + sizeof(struct ether_vlan_header)), which makes it > IP_MAXPACKET. The value of if_hw_tsomax must be <= IP_MAXPACKET and I'm guessing this is what caused the above panic. (Someday it would be nice if TSO segments > IP_MAXPACKET could be handled, but that will take changes in the ip layer and router software so that a bogus ip_len field doesn't cause problems.) if_hw_tsomax needs to be the maximum segment size that the driver can accept from IP. Since the driver adds any MAC header after accepting the TSO segment from the IP layer, it shouldn't include MAC header(s) in the value for if_hw_tsomax. (If its limit includes MAC header(s), it needs to subtract those out when setting if_hw_tsomax, not add them.) Since I am working up a patch for the value of if_hw_tsomaxsegcount, I think I'll add a check for > IP_MAXPACKET for if_hw_tsomax as well. rick > -- > Joel > _______________________________________________ > freebsd-current@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" >
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