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 http://people.freebsd.org/~brueffer/screenlog.0.gz - Christian -- 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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