Operating Systems Concepts , 6^th Edition (with XP Update)
Silberschatz, Galvin and Gagne
Addison Wesley, 2003.

Advanced Programming in UNIX environment ,
W. Richard Stevens,Addison Wesley, 1992.

Other references:

1. 

   Beck, Bohme, Dziadzka, Kunitz, Magnus, Schroter and Verworner, Linux Kernel Programming, Third Edition, Addison-Wesley, 2002.
2. Andrew Tanenbaum, Modern Operating Systems, Prentice-Hall, 2001.