About kern/57136, panic assertion, probably a diagnotic panic

[Brad Spencer <brad%anduin.eldar.org@localhost>]

gnats-admin%netbsd.org@localhost writes:

I wrote this PR a little while ago.....

kern/57136: NPF panic probably on a NPF table list call

>>Category:       kern
>>Responsible:    kern-bug-people
>>Synopsis:       NPF panic probably on a NPF table list call
>>Arrival-Date:   Fri Dec 23 20:20:00 +0000 2022

I was finally able to catch more of the panic message.  It appears to be
a diagnostic assertion in kern_synch.c.  Copied from an image this is
the assert:

panic: kernel diagnostic assertion "ci->ci_mtx_count == -1" failed: file "../../../../kern/kern_synch.c", line 726 mi_switch: cpu0: ci_mtx_count (-2) != -1 (block with spin-mutex held)

(following that is the panic I copied into the PR)

The system is a pure PVH DOMU running a 10.0_BETA mostly GENERIC kernel
with 2 VCPUS and 12GB of memory.  What was going on at the time was a
tar-pipe copy "tar -cf - . | (cd /someplace;tar -xvf -)" and probably a
pretty large network burst of activity from another system on the lan
into the DOMU (and a bunch of other stuff, like being a router and
firewall).  The trigger of the panic is as mentioned in the PR, a
"npfctl table sometable list" was performed from a cron job, but that
wasn't where the actual panic happened, it seems. ...  so lots of Xen
guest disk and some Xen network activity was present.

I have other DOMUs that perform the same npfctl actions just as often
and they never panic... but they also only have 1 VCPU.  The DOMU that
panics is the only one with more than 1 VCPU.  The problem does seem to
get worse, in the sense that the panic happens more often, if 3 VCPUs
are given to the DOMU.  As it is right now, the panic can't exactly be
reproduced upon demand, but pretty much WILL happen at day 6 or so of
uptime if some sort of activity ties up the CPUS (this may be a bit
subjective on my part, but it seems like the system can handle activity
better in days 1 to 5 and only around day 6 does the chances of the
panic increase, but I may also be smoking something...).  With 3 VCPUs,
it was happening about every 30 hours.


Any help or hints would be greatly appreciated.  With some planning I
can perform tests.





-- 
Brad Spencer - brad%anduin.eldar.org@localhost - KC8VKS - http://anduin.eldar.org