kernel panic in NetBSD-9.1-amd64-install.img (exiting unheld spin mutex)

["Jeremy C. Reed" <reed%reedmedia.net@localhost>]

I booted NetBSD-9.1-amd64-install.img

I didn't install.

For about 30 minutes I attempted to get my athn device working as an 
access point plus using dhcpd and hostapd (they are on the installer 
system which I didn't know before). My android phone could get to a 
"connecting ..." state but never connected to it.

I ran multiple times:

ifconfig athn0 inet 172.16.1.1 media autoselect mediaopt hostap chan 5 nwkey aaaaaaaa

(in between using dhcpd and hostap and tcpdump)

I had dhcpd and tcpdump running in background

the final time I got a kernel panic

Mutex error: mutex_vector_exit,742: exiting unheld spin mutex
...

panic: lock error: Mutex error: mutex_vector_exit,742: exiting unheld 
spin mutex: lock 0xffff8699588015c0 cpu 0 lwp 0xff... (my photo was 
cropped)

...

vpanic() at netbsd:vpanic+0x160
snprintf() at netbsd:snprintf
...

athn_ioctl() at netbsd:athn_ioctl+0x18b
if_mcast_op() at netbsd:if_mcast_op+0x4b

(sorry I don't type all in)

in_delmulti
in_scrubaddr
in_purgeaddr
in_control0
udp_ioctl_wrapper
compat_ifioctl
doifioctl
sys_ioctl
syscall
...
--- syscall (number 54) ---
74df3936822a:
cpu0: End traceback...

I can type in the rest if needed.