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Date:      Wed, 1 May 2013 20:57:04 -0400
From:      Glen Barber <gjb@FreeBSD.org>
To:        John Baldwin <jhb@freebsd.org>
Cc:        Ian FREISLICH <ianf@clue.co.za>, freebsd-current@freebsd.org, "Robert N. M. Watson" <rwatson@freebsd.org>
Subject:   Re: panic: in_pcblookup_local (?)
Message-ID:  <20130502005704.GB1623@glenbarber.us>
In-Reply-To: <201305011430.37106.jhb@freebsd.org>
References:  <E1UW0K5-000P7H-36@clue.co.za> <20130501180321.GA44525@glenbarber.us> <49916D2B-496A-40EA-971F-62951FF6B584@freebsd.org> <201305011430.37106.jhb@freebsd.org>

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On Wed, May 01, 2013 at 02:30:36PM -0400, John Baldwin wrote:
> On Wednesday, May 01, 2013 2:08:57 pm Robert N. M. Watson wrote:
> > If in DDB, it would be useful to do a "ps" so we can identify threads i=
n the=20
> > process, and in particular, whether they might be in the kernel around =
the=20
> > moment of the panic.
> >=20
> > > I will follow up with this information as soon as possible.
> >=20
> > Thanks. Do keep around as much information as you can from DDB, crashdu=
mps,=20
> > etc. A useful set of things to keep from DDB includes the initial panic=
=20
> > information and trap frame, "show pcpu", "show allpcpu", "trace", "allt=
race",=20
> > "ps", and if WITNESS is compiled in, "show locks" and "show alllocks". =
On busy=20
> > systems, all the backtraces add up to a lot of space, so you might hold=
 onto=20
> > that rather than e-mail it, but contain useful information. Often, debu=
gging=20
> > this sort of race condition involves looking at what other network-cent=
red=20
> > threads are doing -- e.g., device-driver ithreads, netisr, other involv=
ed user=20
> > threads. You may be able to extract much of that information using ps o=
n the=20
> > crashdump (not sure if procstat is there yet for crashdumps) -- if so, =
be sure=20
> > to use -H (or whatever the argument is to print thread, not just proces=
s,=20
> > information).
>=20

So, I am admittedly not too familiar with DDB.  In fact, I just now
realize the kernel is built without DDB...

Additionally, the kernel is built without WITNESS.

> You can also grab my kgdb scripts from www.freebsd.org/~jhb/gdb/
>=20

Thanks for these.

> Put those in a dir and do 'source gdb6'.  You can then run 'ps' to get a =
good=20
> ps listing that includes threads.  You can also use 'thread apply all bt'=
 to=20
> get stacktraces of all threads in kgdb.  I believe there is an 'allpcpu'=
=20
> command that is similar to 'show allpcpu' in DDB.
>=20

I have the outputs of 'ps', 'allpcpu', and 'thread apply all bt' saved
to separate script(1) files.  Is there anything in particular I can look
for before uploading the files somewhere public?  At quick-ish look
though, I did not see anything cf-agent (the current process at time of
panic) related.

> Robert, in this case he has a full crashdump, so we can get quite a bit o=
f=20
> information from it.
>=20

Right, and I can keep anything available for as long as necessary.

Glen


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