panic with bpf-using tool

[Thomas Klausner <tk%giga.or.at@localhost>]

I just started net/trafshow for fun and shortly afterwards the machine
paniced (NetBSD 8.99.7/amd64):

WARNING: SPL NOT LOWERED ON SYSCALL 1 235601568 EXIT 176106b0 7
WARNING: SPL NOT LOWERED ON SYSCALL 1 235601568 EXIT 176106b0 7
vpanic() at netbsd:vpanic+0x140
snprintf() at netbsd:snprintf
lockdebug_abort() at netbsd:lockdebug_abort+0x6e
mutex_vector_exit() at netbsd:mutex_vector_exit+0xe4
callout_halt() at netbsd:callout_halt+0xe6
bpf_read() at netbsd:bpf_read+0x199
dofileread() at netbsd:dofileread+0x8f
sys_read() at netbsd:sys_read+0x5f
syscall() at netbsd:syscall+0x1d8
--- syscall (number 3) ---
7bb169e3e1fa:
cpu9: End traceback...

Any ideas?
 Thomas