If SPARSEMEM, use page_ext in mem_section
if !SPARSEMEM, use page_ext in pgdata
Signed-off-by: NWeijie Yang <weijie.yang@samsung.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>