For which kind of fault the page is checked first in unix?

Question

Hello
For which kind of fault the page is checked first in unix?
please reply me. i am waiting for your reply.
Thanx

Answer 1

The page is first checked for the validity fault, as soon as it is found that the page is invalid (valid bit is clear), the validity fault handler returns immediately, and the process incur the validity page fault. Kernel handles the validity fault and the process will incur the protection fault if any one is present.