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>