syzbot

login: panic: rtrequest1_fib: locked
cpuid = 0
time = 1552901891
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe0020dbb270
vpanic() at vpanic+0x1e0/frame 0xfffffe0020dbb2d0
panic() at panic+0x43/frame 0xfffffe0020dbb330
rtrequest1_fib() at rtrequest1_fib+0x151d/frame 0xfffffe0020dbb450
route_output() at route_output+0x122d/frame 0xfffffe0020dbb6d0
sosend_generic() at sosend_generic+0x73d/frame 0xfffffe0020dbb7a0
sosend() at sosend+0xc6/frame 0xfffffe0020dbb810
kern_sendit() at kern_sendit+0x35e/frame 0xfffffe0020dbb8c0
sendit() at sendit+0x226/frame 0xfffffe0020dbb920
sys_sendto() at sys_sendto+0x5c/frame 0xfffffe0020dbb980
amd64_syscall() at amd64_syscall+0x436/frame 0xfffffe0020dbbab0
fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe0020dbbab0
--- syscall (0, FreeBSD ELF64, nosys), rip = 0x41c2ea, rsp = 0x7fffffffead8, rbp = 0x7fffffffeb40 ---
KDB: enter: panic
[ thread pid 759 tid 100080 ]
Stopped at      kdb_enter+0x6a: movq    $0,kdb_why