Fatal trap 12: page fault while in kernel mode
cpuid = 0
fault virtual address	= 0x20
fault code		= supervisor read, page not present
instruction pointer	= 0x2b:0x4c6a2b
stack pointer	        = 0x10:0x80142df2c0
frame pointer	        = 0x10:0x80142df860
processor eflags	= interrupt enabled, resume, IOPL = 0
current process		= 4 (df5337)
current thread          = pri 6 
 <- SMP: XXX
kernel: type 12 trap, code=0

CPU0 stopping CPUs: 0x0000000000000002
 stopped
Stopped at      0x4c6a2b:       cmpl    %edi,0x20(%rax)
db> trace
uifind() at 0x4c6a2b
change_euid() at 0x4c3426
sys_seteuid() at 0x4c34f7
syscall2() at 0x71f2a4
go_user() at 0x720138
db>