http://gogojesseco.blogspot.tw/2009/07/linux-mmap.html
http://www.jollen.org/blog/2007/03/mmap_vma.html
http://fanqiang.chinaunix.net/a4/b8/20010526/110000243_b.html
http://www.lslnet.com/linux/docs/linux-5064.htm
http://www.perfgeeks.com/?p=723
http://my.oschina.net/orion/blog/32218