title: mmap() internals
body: <p>It's widely known that the most significant mmap() feature is that file mapping is shared between many processes. But it's not less widely known that every process has its own address space.</p>
  
  <p>The question is where are memmapped files (more specifically, its data) truly kept, and how processes can get access to this memory?
  I mean not *(pa+i) and other high-level stuff, but I mean the internals of the process.</p>