Re: mmap how does kernel know a page is mmaped

On Thu, 25 Jul 2013 10:52:43 -0700, kernel neophyte said:

I am sorry maybe I did not ask the question correctly, all I want to know is how mmap works underneath, given an address X how does kernel figure out its a mmaped page ?

You missed the point. The kernel never checks if it's an mmap'ed page. It merely checks is this a mapped page, the same way it checks every single other memory reference whether it's a code segment, your stack, your heap... it doesn't care that address 0x3FB0CCF0 is mmap'ed or not. It just cares "does this throw a pagefault when I reference it?" - and then it gets handled just like any other page fault.