lock error in [ 559.ADDR] do_sys_accept

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 267661aa Rename and partially enable trace_thread ATF ptra..
git tree: netbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=112047cca00000
dashboard link: https://syzkaller.appspot.com/bug?extid=ad47b70016a166f4c610

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+ad47b7...@syzkaller.appspotmail.com

[ 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


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[Maxime Villard]

#syz dup: lock error in [ 81.ADDR] do_sys_accept