panic: mtx_lock() of spin mutex (null) @ /syzkaller/managers/main/kernel/sys/kern/sys_socket.c:774
cpuid = 0
time = 1558179374
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe001f994700
vpanic() at vpanic+0x1e0/frame 0xfffffe001f994760
panic() at panic+0x43/frame 0xfffffe001f9947c0
__mtx_lock_flags() at __mtx_lock_flags+0x1fd/frame 0xfffffe001f994820
soo_aio_cancel() at soo_aio_cancel+0x77/frame 0xfffffe001f994860
aio_cancel_job() at aio_cancel_job+0xc7/frame 0xfffffe001f9948a0
aio_proc_rundown() at aio_proc_rundown+0xd7/frame 0xfffffe001f994900
exit1() at exit1+0x560/frame 0xfffffe001f994970
sys_sys_exit() at sys_sys_exit+0xd/frame 0xfffffe001f994980
amd64_syscall() at amd64_syscall+0x436/frame 0xfffffe001f994ab0
fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe001f994ab0
--- syscall (1, FreeBSD ELF64, sys_sys_exit), rip = 0x44f54a, rsp = 0x7fffdffdce88, rbp = 0x4fcef8 ---
KDB: enter: panic
[ thread pid 1571 tid 100129 ]
Stopped at      kdb_enter+0x6a: movq    $0,kdb_why