Date: Tue, 4 Mar 2003 08:40:09 -0600 (CST) From: Jonathan Lemon <jlemon@flugsvamp.com> To: roam@ringlet.net, stable@freebsd.org Subject: Re: 4.8-PRE (and earlier) crash - syncookies? Message-ID: <200303041440.h24Ee9ha074389@mail.flugsvamp.com> In-Reply-To: <local.mail.freebsd-stable/20030304115918.GA554@straylight.oblivion.bg>
next in thread | previous in thread | raw e-mail | index | archive | help
In article <local.mail.freebsd-stable/20030304115918.GA554@straylight.oblivion.bg> you write: >-=-=-=-=-=- >-=-=-=-=-=- > >Hi, > >I think this has been going on for a couple of months; unfortunately, I >cannot remember exactly when it started :( Several machines, which have >always been updated synchronously at intervals of a couple of weeks or >so, have been experiencing panics every few days with recent 4.6-STABLE, >4.7-STABLE, and 4.8-PRERELEASE kernel+world. > >Attached is the kernel config and a gdb session of the most recent >crashdump. Maybe the most interesting part is at the end of the gdb >session: is there a normal reason why a TAILQ structure would have a >null start pointer, and an end pointer pointing back to itself? [ ... ] >#16 0xc01b2768 in syncache_insert (sc=0xcb870b80, sch=0xc0eeeb7c) > at /usr/src/sys/netinet/tcp_syncache.c:289 >289 sc2 = TAILQ_FIRST(&sch->sch_bucket); >(kgdb) print sch >$1 = (struct syncache_head *) 0xc0eeeb7c >(kgdb) print *sch >$2 = {sch_bucket = {tqh_first = 0x0, tqh_last = 0xc0eeeb7c}, > sch_length = 4294967295} It looks to me like the tailq is empty (first == null, last == &head), but the code path to remove an entry was taken because the length counter indicated it was over the bucket limit. sch_length == -1. So my guess is the code dropped a syncache entry twice, and this is the resulting mess. Can you print out the contents of tcp_syncache and tcpstat? -- Jonathan To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200303041440.h24Ee9ha074389>