How does the Linux kernel distinguish between a page fault caused by a bad user pointer vs a kernel bug when both occur in Ring 0? – unix.stackexchange.com
Bhushitha Hashan
I understand that when a page fault occurs in user space
(Ring 3), the fault handler can read the saved CS register
from pt_regs to confirm CPL=3, then send SIGSEGV to the
process and keep the kernel ...