[ Based on original patch from Christoph Lameter and Mike Travis. ]

  * Ruggedize some calls in setup_percpu.c to prevent mishaps
    in early calls, particularly for non-critical functions.

  * Cleanup DEBUG_PER_CPU_MAPS usages and some comments.
Signed-off-by: NMike Travis <travis@sgi.com>
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>