mm/writeback: correct dirty page calculation for highmem

ZONE_MOVABLE could be treated as highmem so we need to consider it for
accurate calculation of dirty pages.  And, in following patches,
ZONE_CMA will be introduced and it can be treated as highmem, too.  So,
instead of manually adding stat of ZONE_MOVABLE, looping all zones and
check whether the zone is highmem or not and add stat of the zone which
can be treated as highmem.

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@suse.de>
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, 6 insertions, 2 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index bc5149d5ec38..3b88795ab46e 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -296,11 +296,15 @@ static unsigned long highmem_dirtyable_memory(unsigned long total)
 #ifdef CONFIG_HIGHMEM
         int node;
         unsigned long x = 0;
+        int i;
 
         for_each_node_state(node, N_HIGH_MEMORY) {
-                struct zone *z = &NODE_DATA(node)->node_zones[ZONE_HIGHMEM];
+                for (i = 0; i < MAX_NR_ZONES; i++) {
+                        struct zone *z = &NODE_DATA(node)->node_zones[i];
 
-                x += zone_dirtyable_memory(z);
+                        if (is_highmem(z))
+                                x += zone_dirtyable_memory(z);
+                }
         }
         /*
          * Unreclaimable memory (kernel memory or anonymous memory