kern/55611: panic on shutdown

[martin%NetBSD.org@localhost]

>Number:         55611
>Category:       kern
>Synopsis:       panic on shutdown
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Aug 28 08:55:00 +0000 2020
>Originator:     Martin Husemann
>Release:        NetBSD 9.99.71
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD gethsemane.duskware.de 9.99.71 NetBSD 9.99.71 (GETHSEMANE) #75: Fri Aug 28 09:32:50 CEST 2020 martin%seven-days-to-the-wolves.aprisoft.de@localhost:/work/src/sys/arch/macppc/compile/GETHSEMANE macppc
Architecture: powerpc
Machine: macppc

(actually the running kernel was ~1 day older, I was rebooting after installing
the new kernel)

>Description:

Installed a new kernel, did "shutdown -r now" and it ended like this:

syslogd[993]: Exiting on signal 15
[ 954.5799395] panic: kernel diagnostic assertion "sn->sn_opencnt == 0" failed: file "../../../../miscfs/specfs/spec_vnops.c", line 414 
[ 954.5999499] cpu1: Begin traceback...
[ 954.6099548] 0x1065db40: at vpanic+0x12c
[ 954.6199623] 0x1065db70: at kern_assert+0x60
[ 954.6299665] 0x1065dbb0: at spec_node_revoke+0x108
[ 954.6399731] 0x1065dbd0: at vcache_reclaim+0x664
[ 954.6399731] 0x1065dc60: at vgone+0x114
[ 954.6399731] 0x1065dc80: at vrevoke+0x114
[ 954.6399731] 0x1065dcb0: at genfs_revoke+0x1c
[ 954.6800071] 0x1065dcc0: at VOP_REVOKE+0x48
[ 954.6800071] 0x1065dce0: at exit1+0x784
[ 954.6800071] 0x1065dd90: at sigexit+0x20c
[ 954.7000105] 0x1065ddc0: at postsig+0x284
[ 954.7000105] 0x1065de70: at lwp_userret+0x204
[ 954.7000105] 0x1065deb0: at syscall+0x4cc
[ 954.7400380]             r1=0xffffe440 cr=0x22082224 xer=0 ctr=0xfdc30d30
[ 954.7400380] cpu1: End traceback...
[ 954.7700474] halting CPU 0


Not reproducable.

>How-To-Repeat:
Only saw it once.

>Fix:
n/a