Linux VAS Management

Where in the line of code which alternates between virtual address spaces (vas) in the Linux kernel? I know Linux describes the vas with struct mm_struct, but can't find the开发者_开发知识库 actual code.

Although I do not possess in-depth knowledge about the Linux kernel, I think looking at code in mm/memory.c ( http://lxr.linux.no/linux+v3.0.4/mm/memory.c ) could provide you some pointers for what you are looking for. LDT mentioned by @Ignacio Vazquez-Abrams is specifically for x86's Local Descriptor Table the code for which is present in arch/x86/kernel/ldt.c. Browsing through the source will be the best option to learn more I guess.
Hope this helps!