mem_map_reserve, mem_map_unreserve - Manipulate flags of
       virtual memory pages.

SYNOPSIS

       #include <linux/mm.h>
       #include <linux/wrapper.h>

       #define mem_map_reserve(page_nr)
       #define mem_map_unreserve(page_nr)

DESCRIPTION

       These macros cause a page to become reserved/unreserved. A
       reserved  page  is reserved from any further consideration
       by the linux kernel, meaning it is not scanned  as  poten­
       tially  pageable,  or  available  for page allocation. The
       kernel treats reserved pages as memory-mapped hardware.

       It makes sense for a driver to mark a page  reserved,  for
       example,  if  the driver supports mmap(2) with dynamically
       allocated pages that the target device can access via DMA.

RETURN VALUE

       None

AVAILABILITY

       Linux 2.0+

SEE ALSO

       MAP_NR(9), get_free_pages(9), mmap(2)

AUTHOR

       Stephen Williams <steve@icarus.com>

BUGS

       If  a page is marked reserved, a call to free_page(9) will
       silenty ignore it. If the page was originally allocated by
       get_free_page, you must remember to unmark the page before
       releasing it to the system. Otherwise, the page is lost.