mm: don't drop a partial page in a zone's memory map size

In a zone's present pages number, account for all pages occupied by the
memory map, including a partial.

Signed-off-by: Johannes Weiner <hannes@saeurebad.de>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6383557..0353002 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3378,7 +3378,8 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat,
                 * is used by this zone for memmap. This affects the watermark
                 * and per-cpu initialisations
                 */
-               memmap_pages = (size * sizeof(struct page)) >> PAGE_SHIFT;
+               memmap_pages =
+                       PAGE_ALIGN(size * sizeof(struct page)) >> PAGE_SHIFT;
                if (realsize >= memmap_pages) {
                        realsize -= memmap_pages;
                        printk(KERN_DEBUG