Fatal trap 12: page fault while in kernel mode
cpuid = 1; apic id = 01
fault virtual address	= 0x0
fault code		= supervisor read data, page not present
instruction pointer	= 0x20:0xffffffff810056d1
stack pointer	        = 0x28:0xfffffe001a178b70
frame pointer	        = 0x28:0xfffffe001a178ba0
code segment		= base 0x0, limit 0xfffff, type 0x1b
			= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags	= resume, IOPL = 0
current process		= 13 (g_up)
trap number		= 12
panic: page fault
cpuid = 1
time = 1
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x47/frame 0xfffffe001a1787c0
vpanic() at vpanic+0x1c7/frame 0xfffffe001a178820
panic() at panic+0x43/frame 0xfffffe001a178880
trap_fatal() at trap_fatal+0x4ca/frame 0xfffffe001a178900
trap_pfault() at trap_pfault+0xdc/frame 0xfffffe001a178980
trap() at trap+0x3f8/frame 0xfffffe001a178aa0
calltrap() at calltrap+0x8/frame 0xfffffe001a178aa0
--- trap 0xc, rip = 0xffffffff810056d1, rsp = 0xfffffe001a178b70, rbp = 0xfffffe001a178ba0 ---
_thread_lock() at _thread_lock+0x41/frame 0xfffffe001a178ba0
g_up_procbody() at g_up_procbody+0x23/frame 0xfffffe001a178bb0
fork_exit() at fork_exit+0xb3/frame 0xfffffe001a178bf0
fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe001a178bf0
--- trap 0, rip = 0, rsp = 0, rbp = 0 ---
KDB: enter: panic
[ thread pid 13 tid 100023 ]
Stopped at      kdb_enter+0x67: movq    $0,0x146d276(%rip)
db>