Date: Tue, 16 Oct 2012 12:15:33 -0400 From: John Baldwin <jhb@freebsd.org> To: dg17@penx.com Cc: freebsd-fs@freebsd.org Subject: Re: I have a DDB session open to a crashed ZFS server Message-ID: <201210161215.33369.jhb@freebsd.org> In-Reply-To: <1350400597.72003.32.camel@btw.pki2.com> References: <1350317019.71982.50.camel@btw.pki2.com> <201210160844.41042.jhb@freebsd.org> <1350400597.72003.32.camel@btw.pki2.com>
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On Tuesday, October 16, 2012 11:16:37 am Dennis Glatting wrote:
> On Tue, 2012-10-16 at 08:44 -0400, John Baldwin wrote:
> > On Monday, October 15, 2012 12:03:39 pm Dennis Glatting wrote:
> > > FreeBSD/amd64 (mc) (ttyu0)
> > >
> > > login: NMI ... going to debugger
> > > [ thread pid 11 tid 100003 ]
> >
> > You got an NMI, not a crash. What happens if you just continue ('c' command)
> > from DDB?
> >
>
> I hit the NMI button because of the "crash," which is a misword, to get
> into DDB.
Ah, I would suggest "hung" or "deadlocked" next time. It certainly seems like
a deadlock since all CPUs are idle. Some helpful commands here might be
'show sleepchain' and 'show lockchain'.
Pick a "stuck" process (like find) and run:
'show sleepchain <pid>'
In your case though it seems both 'find' and the various 'pbzip2' threads
are stuck on a condition variable, so there isn't an easy way to identify
an "owner" that is supposed to awaken these threads. It could be a case
of a missed wakeup perhaps, but you'll need to get someone more familiar
with ZFS to identify where these codes should be awakened normally.
--
John Baldwin
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