lock error in [ 1740.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=15820a48a00000
dashboard link: https://syzkaller.appspot.com/bug?extid=a8060444ef1ac1a07e79
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1440040ca00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+a80604...@syzkaller.appspotmail.com

[ 1740.6258716] panic: lock error: Mutex: mutex_vector_exit,761: assertion
failed: MUTEX_OWNER(mtx->mtx_owner) == curthread: lock 0xffffb40012f523c0
cpu 1 lwp 0xffffb40012ffe600
[ 1740.6365115] cpu1: Begin traceback...
[ 1740.6471554] vpanic() at netbsd:vpanic+0x214
[ 1740.6684381] snprintf() at netbsd:snprintf
[ 1740.6790816] lockdebug_abort() at netbsd:lockdebug_abort+0x14c
[ 1740.6897224] mutex_vector_exit() at netbsd:mutex_vector_exit+0x1bc
[ 1740.7003624] do_sys_accept() at netbsd:do_sys_accept+0x346
[ 1740.7110068] sys_accept() at netbsd:sys_accept+0xac
[ 1740.7216580] sys___syscall() at netbsd:sys___syscall+0xe2
[ 1740.7322938] syscall() at netbsd:syscall+0x348
[ 1740.7429303] --- syscall (number 198) ---
[ 1740.7429303] 73d86183f4aa:
[ 1740.7535699] cpu1: End traceback...

[ 1740.7535699] dumping to dev 4,1 (offset=0, size=0): not possible
[ 1740.7642081] 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


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[Maxime Villard]

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