[RFC 02/16] mm/writeback: correct dirty page calculation for highmem

[Joonsoo Kim]

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@xxxxxxx>
---
 mm/page-writeback.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 19ceae8..942f6b3 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -198,11 +198,15 @@ 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
-- 
1.7.9.5

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