Fatal trap 9: general protection fault while in kernel mode
cpuid = 0; apic id = 00
instruction pointer	= 0x20:0xffffffff81163cf5
stack pointer	        = 0x28:0xfffffe0021268610
frame pointer	        = 0x28:0xfffffe0021268650
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 1021 (syz-executor.2)
trap number		= 9
panic: general protection fault
cpuid = 0
time = 1552846104
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe00212682e0
vpanic() at vpanic+0x1e0/frame 0xfffffe0021268340
panic() at panic+0x43/frame 0xfffffe00212683a0
trap_fatal() at trap_fatal+0x4c6/frame 0xfffffe0021268420
trap() at trap+0xba/frame 0xfffffe0021268540
calltrap() at calltrap+0x8/frame 0xfffffe0021268540
--- trap 0x9, rip = 0xffffffff81163cf5, rsp = 0xfffffe0021268610, rbp = 0xfffffe0021268650 ---
unp_dispose() at unp_dispose+0xa5/frame 0xfffffe0021268650
sofree() at sofree+0x42c/frame 0xfffffe00212686b0
soclose() at soclose+0x5b3/frame 0xfffffe0021268730
_fdrop() at _fdrop+0x3a/frame 0xfffffe0021268760
closef() at closef+0x27d/frame 0xfffffe00212687f0
fdescfree_fds() at fdescfree_fds+0xbd/frame 0xfffffe0021268840
fdescfree() at fdescfree+0x58a/frame 0xfffffe0021268900
exit1() at exit1+0x780/frame 0xfffffe0021268970
sys_sys_exit() at sys_sys_exit+0xd/frame 0xfffffe0021268980
amd64_syscall() at amd64_syscall+0x436/frame 0xfffffe0021268ab0
fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe0021268ab0
--- syscall (1, FreeBSD ELF64, sys_sys_exit), rip = 0x44f30a, rsp = 0x7fffffffec58, rbp = 0x1 ---
KDB: enter: panic
[ thread pid 1021 tid 100114 ]
Stopped at      kdb_enter+0x6a: movq    $0,kdb_why