syzbot

Fatal trap 12: page fault while in kernel mode
cpuid = 0; apic id = 00
fault virtual address	= 0x0
fault code		= supervisor read data, page not present
instruction pointer	= 0x20:0xffffffff80e4e45f
stack pointer	        = 0x28:0xfffffe002a3c4400
frame pointer	        = 0x28:0xfffffe002a3c4430
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		= 7465 (syz-executor.3)
trap number		= 12
panic: page fault
cpuid = 0
time = 4115
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe002a3c4060
vpanic() at vpanic+0x1e0/frame 0xfffffe002a3c40c0
panic() at panic+0x43/frame 0xfffffe002a3c4120
trap_fatal() at trap_fatal+0x4c6/frame 0xfffffe002a3c41a0
trap_pfault() at trap_pfault+0x9f/frame 0xfffffe002a3c4210
trap() at trap+0x44d/frame 0xfffffe002a3c4330
calltrap() at calltrap+0x8/frame 0xfffffe002a3c4330
--- trap 0xc, rip = 0xffffffff80e4e45f, rsp = 0xfffffe002a3c4400, rbp = 0xfffffe002a3c4430 ---
fifo_close() at fifo_close+0x1f/frame 0xfffffe002a3c4430
VOP_CLOSE_APV() at VOP_CLOSE_APV+0xc2/frame 0xfffffe002a3c4460
vgonel() at vgonel+0xdc/frame 0xfffffe002a3c44e0
vflush() at vflush+0x3df/frame 0xfffffe002a3c4630
ffs_flushfiles() at ffs_flushfiles+0x1eb/frame 0xfffffe002a3c46a0
softdep_flushfiles() at softdep_flushfiles+0x105/frame 0xfffffe002a3c4740
ffs_unmount() at ffs_unmount+0xc1/frame 0xfffffe002a3c47d0
dounmount() at dounmount+0x6e8/frame 0xfffffe002a3c4850
vfs_unmountall() at vfs_unmountall+0x6b/frame 0xfffffe002a3c4880
bufshutdown() at bufshutdown+0x4d1/frame 0xfffffe002a3c48d0
kern_reboot() at kern_reboot+0x31e/frame 0xfffffe002a3c4920
sys_reboot() at sys_reboot+0x467/frame 0xfffffe002a3c4980
amd64_syscall() at amd64_syscall+0x436/frame 0xfffffe002a3c4ab0
fast_syscall_common() at fast_syscall_common+0x101/frame 0xfffffe002a3c4ab0
--- syscall (55, FreeBSD ELF64, sys_reboot), rip = 0x2000000b, rsp = 0x7fffdfffdeb8, rbp = 0xa ---
KDB: enter: panic
[ thread pid 7465 tid 100279 ]
Stopped at      kdb_enter+0x6a: movq    $0,kdb_why