Re: panic: witness_warn head/amd64 _at_r285741 on 1 of 2 machines

On Tue, Jul 21, 2015 at 03:21:16PM -0500, Eric van Gyzen wrote:
> ...
> >> So it looks like net swi, leaking some udp6 lock.
> > Curiouser and curiouser...  While I'm not taking any special pains to
> > avoid building IPv6, I'm not actively actually doing anything with it
> > (IPv6), either (for both the failing machine and my laptop).
> >
> > Once I'm back home, I should be able to poke around in ddb after
> > re-creating the panic, if that would be a useful thing for me to do (and
> > given some hints as to what to poke).
> >
> > Naturally, I'm also happy to change bits of sources, rebuild, and
> > smoke-test.
> >
> > A quick check from the SVN update output only shows r285710, r285711, and
> > r285740 in the range from (r285685,r285741] -- as the kernel running
> > r285685 had no known issues -- that touched sys/netinet6/*.
> 
> It's a multicast destination.  Maybe something is using mDNS?
> 
> Randall, does the test on line 406 of udp6_usrreq.c need to be inverted?
> 
> Eric
> 

<DING!>  We have a winner!

FreeBSD freebeast.catwhisker.org 11.0-CURRENT FreeBSD 11.0-CURRENT #1789  r285741M/285741:1100077: Tue Jul 21 14:50:59 PDT 2015     root_at_freebeast.catwhisker.org:/common/S3/obj/usr/src/sys/GENERIC  amd64

freebeast(11.0-C)[3] cd /usr/src
freebeast(11.0-C)[4] svn diff sys/netinet
netinet/  netinet6/ 
freebeast(11.0-C)[4] svn diff sys/netinet*
Index: sys/netinet6/udp6_usrreq.c
===================================================================
--- sys/netinet6/udp6_usrreq.c  (revision 285741)
+++ sys/netinet6/udp6_usrreq.c  (working copy)
_at__at_ -403,7 +403,7 _at__at_
                INP_RLOCK(last);
                INP_INFO_RUNLOCK(pcbinfo);
                UDP_PROBE(receive, NULL, last, ip6, last, uh);
-               if (udp6_append(last, m, off, &fromsa)) 
+               if (! udp6_append(last, m, off, &fromsa)) 
                        INP_RUNLOCK(last);
        inp_lost:
                return (IPPROTO_DONE);
freebeast(11.0-C)[5] 

Thanks! :-)

Peace,
david
-- 
David H. Wolfskill				david_at_catwhisker.org
Those who murder in the name of God or prophet are blasphemous cowards.

See http://www.catwhisker.org/~david/publickey.gpg for my public key.