http://duartes.org/gustavo/blog/post/how-the-kernel-manages-your-memory/
http://duartes.org/gustavo/blog/post/page-cache-the-affair-between-memory-and-files/
https://www.kernel.org/doc/gorman/pdf/understand.pdf
http://www.wowotech.net/kernel_synchronization/memory-barrier-1.html