The idea behind this patch is to create a nodemask_t as a node analog of
cpumask_t.  As NUMA machines become more common, the need for a standard,
cross-platform bitmap of both online & possible nodes becomes more
apparent.  We believe we've worked out most of the kinks of the variable
length bitmap types with the recent cpumask_t patches.  Nodemasks are also
currently far less widespread than cpumasks.  Further, inclusion at this
point in the kernel would mean consistency in node handling between 2.6 and
2.7.

Future goals would be to get rid of the 'numnodes' variable used to count
the number of online nodes, and replace with node_online_map.  This would
allow arbitrary node numbering and facilitate node hotplugging.

(Nothing actually uses this yet, but several projects need it, and it does
model a well-defined physical grouping).
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>