panic: mtx_lock() of destroyed mutex @ /syzkaller/managers/main/kernel/sys/kern/sys_socket.c:309
cpuid = 0
time = 1557505974
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe001fa9f6d0
vpanic() at vpanic+0x1e0/frame 0xfffffe001fa9f730
panic() at panic+0x43/frame 0xfffffe001fa9f790
__mtx_lock_flags() at __mtx_lock_flags+0x1e2/frame 0xfffffe001fa9f7f0
soo_stat() at soo_stat+0x9c/frame 0xfffffe001fa9f830
kern_fstat() at kern_fstat+0xe9/frame 0xfffffe001fa9f880
sys_fstat() at sys_fstat+0x2b/frame 0xfffffe001fa9f980
amd64_syscall() at amd64_syscall+0x436/frame 0xfffffe001fa9fab0
fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe001fa9fab0
--- syscall (198, FreeBSD ELF64, nosys), rip = 0x41309a, rsp = 0x7fffdff79f38, rbp = 0x2 ---
KDB: enter: panic
[ thread pid 893 tid 100411 ]
Stopped at      kdb_enter+0x6a: movq    $0,kdb_why
db>