[PATCH] fix WANT_PAGE_VIRTUAL in memmap_init

I spotted this issue while in memmap_init last week.  I can't say the
change has any test coverage by me.  start_pfn was formerly used in main
"for" loop.  The fix is replace start_pfn with pfn.
Signed-off-by: NBob Picco <bob.picco@hp.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

mm/page_alloc.c

@@ -1667,9 +1667,8 @@ void __init memmap_init_zone(unsigned long size, int nid, unsigned long zone,
 #ifdef WANT_PAGE_VIRTUAL
 		/* The shift won't overflow because ZONE_NORMAL is below 4G. */
 		if (!is_highmem_idx(zone))
-			set_page_address(page, __va(start_pfn << PAGE_SHIFT));
+			set_page_address(page, __va(pfn << PAGE_SHIFT));
 #endif
-		start_pfn++;
 	}
 }