The calculation for node_spanned_pages at grow_pgdat_span() is clearly
wrong.  This is patch for it.

(Please see grow_zone_span() to compare. It is correct.)
Signed-off-by: NYasunori Goto <y-goto@jp.fujitsu.com>
Acked-by: NDave Hansen <haveblue@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>