panic: nfssvc_nfsd(): debug.mpsafenet=1 && Giant
chris at unixpages.org
Wed Aug 25 08:07:33 PDT 2004
On Tue, Aug 24, 2004 at 11:18:55PM -0400, Robert Watson wrote:
> On Tue, 24 Aug 2004, Christian Brueffer wrote:
> > I'm getting the following panic on 6-CURRENT as well as 5.3-BETA1 with
> > sources from today. It's easily reproducible on both, with
> > debug.mpsafenet=1.
> Hmm. Looks like something has acquired and failed to release Giant in the
> NFS server. It could be we're leaking Giant in an error case that didn't
> turn up in previous testing, but for some reason is more common in your
> environment. Unfortunately, as Giant can be acquired recursively, the
> "last acquired" information presented by WITNESS isn't useful to us.
> There are a couple of ways we could approach debugging this. I think the
> easiest might be the following:
> - Recompile your kernel with the following options:
> options KTR
> options KTR_COMPILE=(KTR_LOCK|KTR_PROC)
> options KTR_ENTRIES=16384
> - At run-time, before triggering the crash, use sysctl to set the
> following settings:
> sysctl debug.ktr.cpumask=0xff
> sysctl debug.ktr.mask=`sysctl -n debug.ktr.compile`
> - When the crash occurs, use "show ktr" to list recent lock operations.
> Using your serial console, copy and paste a few pages of locking
> operations into an e-mail, probably until you hit the next context
> switch (mi_switch: new thread). You'll notice that the entries are
> sorted by event id, which generally results in reverse-chronological
> order with most recent event earliest. We'd like to look at all
> acquisitions of Giant and releases of Giant since that context switch.
> There should be one or more acquires than releases in the event stream,
> and we'd like to figure out which is the one not associated with a
> matching unlock.
The complete output is available at
Christian Brueffer chris at unixpages.org brueffer at FreeBSD.org
GPG Key: http://people.freebsd.org/~brueffer/brueffer.key.asc
GPG Fingerprint: A5C8 2099 19FF AACA F41B B29B 6C76 178C A0ED 982D
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