linux - What is "Unable to handle kernel paging request at 00000000313337000" -

i wanted work through independent study http://security.cs.rpi.edu/~candej2/syllabus.pdf myself pick basics on exploit writing , being able write exploit scratch. so... looking @ http://security.cs.rpi.edu/~candej2/kernel/trivial_sploit.c , http://security.cs.rpi.edu/~candej2/kernel/trivial.c, , trying understand how works.

i tried running doing

# insmod trivial.ko $ ./exploit 

the exploit got

[+] mapped 0x31337000 

and then in vm (i set kgdboc), saw

bug: unable handle kernel paging request @ 0000000031337000 ip: [<0000000031337000>] 0x31337000 pgd 3a89e067 pud 3aea2067 pmd 3b333067 pte 31b57067 last sysfs file: /sys/devices/pci0000:00/0000:00:10.0/host2/target2:0:0/2:0:0:0/block/sda/dev kgdb: waiting remote debugger 

why might case?

i found out - it's smep. can disable adding nosmep boot parameter