Suppress split ptlock on arches which may use one page for multiple page
tables.  Reconsider what better to do (particularly on ppc64) later on.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>