lock error in [ 42.ADDR] do_sys_accept

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: c0dd5d0f Format MAP_FMT so that it's more humanly readable..
git tree: netbsd
console output: https://syzkaller.appspot.com/x/log.txt?x=1275e850a00000
dashboard link: https://syzkaller.appspot.com/bug?extid=372c77fd23472055b357
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12bed562a00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15bf0198a00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+372c77...@syzkaller.appspotmail.com

[ 42.7434863] panic: lock error: Mutex: mutex_vector_exit,761: assertion
failed: MUTEX_OWNER(mtx->mtx_owner) == curthread: lock 0xffff918012f07280
cpu 0 lwp 0xffff918012f2c0e0
[ 42.7549432] cpu0: Begin traceback...
[ 42.7549432] vpanic() at netbsd:vpanic+0x214
[ 42.7549432] snprintf() at netbsd:snprintf
[ 42.7635425] lockdebug_abort() at netbsd:lockdebug_abort+0x14c
[ 42.7735685] mutex_vector_exit() at netbsd:mutex_vector_exit+0x1bc
[ 42.7835997] do_sys_accept() at netbsd:do_sys_accept+0x346
[ 42.7835997] sys_accept() at netbsd:sys_accept+0xac
[ 42.7948258] sys_syscall() at netbsd:sys_syscall+0xe2
[ 42.8036551] syscall() at netbsd:syscall+0x348
[ 42.8145952] --- syscall (number 0) ---
[ 42.8145952] 7a7e04a3f4ca:
[ 42.8145952] cpu0: End traceback...

[ 42.8261534] dumping to dev 4,1 (offset=0, size=0): not possible
[ 42.8261534] rebooting...


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[Maxime Villard]

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