sched, numa, mm: Introduce last_nid in the pageframe

sched, numa, mm: Introduce last_nid in the pageframe

Introduce a per-page last_nid field, fold this into the struct
page::flags field whenever possible.

The unlikely/rare 32bit NUMA configs will likely grow the page-frame.

Completely dropping 32bit support for CONFIG_SCHED_NUMA would simplify
things, but it would also remove the warning if we grow enough 64bit
only page-flags to push the last-nid out.

Suggested-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Link: http://lkml.kernel.org/n/tip-0uois4f9skfw9mwyk1yoy0jq@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>