kern/43796: Kernel panic when loading /usr/lkm/pf.o

[clc%intercal.org.uk@localhost]

>Number:         43796
>Category:       kern
>Synopsis:       Kernel panic when loading /usr/lkm/pf.o
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Aug 24 07:30:00 +0000 2010
>Originator:     clc%intercal.org.uk@localhost
>Release:        NetBSD 5.0.2
>Organization:
>Environment:
        
        
System: NetBSD give-up.intercal.org.uk 5.0.2 NetBSD 5.0.2 (XEN3_DOMU) #0: Sat 
Feb 6 13:42:20 UTC 2010 
builds%b8.netbsd.org@localhost:/home/builds/ab/netbsd-5-0-2-RELEASE/amd64/201002061851Z-obj/home/builds/ab/netbsd-5-0-2-RELEASE/src/sys/arch/amd64/compile/XEN3_DOMU
 amd64
Architecture: x86_64
Machine: amd64
>Description:
As soon as I issue the command:

modload /usr/lkm/pf.o

I see a kernel panic message on console:

give-up# modload /usr/lkm/pf.o 
panic: kernel diagnostic assertion "cv_is_valid(cv)" failed: file 
"/home/builds/ab/netbsd-5-0-2-RELEASE/src/sys/kern/kern_condvar.c", line 329
Begin traceback...
copyright() at netbsd:__kernassert+0x2b1f8
uvm_fault(0xffffa000138ce8b0, 0x1000, 1) -> e
fatal page fault in supervisor mode
trap type 6 code 0 rip ffffffff803791b4 cs e030 rflags 10246 cr2  1008 cpl 0 
rsp ffffa000139274f0
panic: trap
Faulted in mid-traceback; aborting...
dump to dev 142,1 not possible
rebooting...

I don't know if this only happens when running under Xen, as I haven't been
able to test on other environments. The only report I have seen which mentions
a similar problem is #38245, however that report mentions older kernels and
this happens with the latest, 5.0.2; also I don't need to load any pf rules
(or in fact don't even have a chance to do that as the panic is immediate).

>How-To-Repeat:
        reboot
        modload /usr/lkm/pf.o
>Fix:

>Unformatted: