vm_address_space --> vm_translation_map 
                 --> vm_virtual_map
                           |--> vm_region ---> vm_cache_ref ---> vm_cache ---> vm_store
                           |                                         |
                           |                                         |--> vm_page
                           |                                         |
                           |                                         |--> vm_page
                           |                                         |
                           |                                         |--> vm_page
                           |                                         |
                           |                                         ~
                           |
                           |--> vm_region ---> vm_cache_ref ---> vm_cache ---> vm_store
                           |                                     ^   |
                           |                                     |   |--> vm_page
                           |                                     |   |
                           |                                     |   |--> vm_page     
                           |                                     |   |
                           |                                     |   ~
                           |                                     |
                           |--> vm_region ---> vm_cache_ref -----/
                           |
                           |
                           |
                           |
                           |--> vm_region ---> vm_cache_ref ---> vm_cache ---> vm_store
                           |                                     ^   |
                           |                                     |   |--> vm_page
                           |                                     |   |
                           |                                     |   |--> vm_page
                           |                                     |   |
                           |                                     |   ~
                           |                                     |
                           |                                     \-----------\
                           |                                                 |
                           |                                                 |
                           |--> vm_region ---> vm_cache_ref ---> vm_cache ---/     <<= this is a private mapping of an existing vm_store
                           |                                         |
                           |                                         |--> vm_page
                           |                                         |
                           |                                         |--> vm_page
                           |                                         |
                           |                                         ~
                           |
                           |
                           ~

NOTES:
 1 vm_address_space per process
 1 vm_translation_map per vm_address_space. vm_translation_map is the equivalent of mach's pmap
 many vm_regions per vm_address_space, sorted by base address
 1 vm_cache_ref per region
 a vm_cache_ref can point to a single vm_cache
 a vm_cache can be pointed to by many vm_cache_refs
 1 vm_store per vm_cache
 many vm_pages per vm_cache
 a vm_page can only be in at most one vm_cache (or none at all if not in use)

 most of these structures can be found at
 http://newos.org/WebSVN/filedetails.php?repname=NewOS&path=%2Fnewos%2Finclude%2Fkernel%2Fvm.h&rev=0&sc=0