Introduce a per-page last_cpu 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_NUMA_BALANCING would simplify
things, but it would also remove the warning if we grow enough 64bit
only page-flags to push the last-cpu 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: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>