lock error in [ 559.ADDR] do_sys

Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported
lock error in [ 81.ADDR] do_sys_accept				1	2082d	2082d
[ 559.8726952] panic: lock error: Mutex: mutex_vector_exit,761: assertion failed: MUTEX_OWNER(mtx->mtx_owner) == curthread: lock 0xffffd28012f44700 cpu 1 lwp 0xffffd28012fde560
[ 559.8838340] cpu1: Begin traceback...
[ 559.9061008] vpanic() at netbsd:vpanic+0x214
[ 559.9061008] snprintf() at netbsd:snprintf
[ 559.9172335] lockdebug_abort() at netbsd:lockdebug_abort+0x14c
[ 559.9283700] mutex_vector_exit() at netbsd:mutex_vector_exit+0x1bc
[ 559.9506450] do_sys_accept() at netbsd:do_sys_accept+0x346
[ 559.9617816] sys_accept() at netbsd:sys_accept+0xac
[ 559.9729227] sys___syscall() at netbsd:sys___syscall+0xe2
[ 559.9840567] syscall() at netbsd:syscall+0x348
[ 559.9840567] --- syscall (number 198) ---
[ 559.9951932] 7a0ce123f4aa:
[ 559.9951932] cpu1: End traceback...

[ 560.0063304] dumping to dev 4,1 (offset=0, size=0): not possible
[ 560.0063304] rebooting...
SeaBIOS (version 1.8.2-20190322_093631-google)
Total RAM Size = 0x00000001e0000000 = 7680 MiB
CPUs found: 2     Max CPUs supported: 2
found virtio-scsi at 0:3
virtio-scsi vendor='Google' product='PersistentDisk' rev='1' type=0 removable=0
virtio-scsi blksize=512 sectors=4194304 = 2048 MiB
drive 0x000f29d0: PCHS=0/0/0 translation=lba LCHS=520/128/63 s=4194304
Booting from Hard Disk 0...

>> NetBSD/x86 BIOS Boot, Revision 5.10 (Tue Jul 17 14:59:51 UTC 2018) (from NetBSD 8.0)
>> Memory: 639/3144640 k

     1. Boot normally
     2. Boot single user
     3. Disable ACPI
     4. Disable ACPI and SMP
     5. Drop to boot prompt