mm/highmem: make nr_free_highpages() handles all highmem zones by itself

nr_free_highpages() manually adds statistics per each highmem zone and
returns a total value for them.  Whenever we add a new highmem zone, we
need to consider this function and it's really troublesome.  Make it
handle all highmem zones by itself.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 8 deletions

diff --git a/mm/highmem.c b/mm/highmem.c
index 123bcd3ed4f2..50b4ca6787f0 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -112,16 +112,12 @@ EXPORT_PER_CPU_SYMBOL(__kmap_atomic_idx);
 
 unsigned int nr_free_highpages (void)
 {
-        pg_data_t *pgdat;
+        struct zone *zone;
         unsigned int pages = 0;
 
-        for_each_online_pgdat(pgdat) {
-                pages += zone_page_state(&pgdat->node_zones[ZONE_HIGHMEM],
-                        NR_FREE_PAGES);
-                if (zone_movable_is_highmem())
-                        pages += zone_page_state(
-                                        &pgdat->node_zones[ZONE_MOVABLE],
-                                        NR_FREE_PAGES);
+        for_each_populated_zone(zone) {
+                if (is_highmem(zone))
+                        pages += zone_page_state(zone, NR_FREE_PAGES);
         }
 
         return pages;