linux-kernel - [PATCH 1/8] mm: vmscan: simplify lruvec_lru

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Date:   Tue, 22 Oct 2019 10:47:56 -0400
From:   Johannes Weiner <hannes@...xchg.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Michal Hocko <mhocko@...e.com>, linux-mm@...ck.org,
        cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-team@...com
Subject: [PATCH 1/8] mm: vmscan: simplify lruvec_lru_size()

This function currently takes the node or lruvec size and subtracts
the zones that are excluded by the classzone index of the
allocation. It uses four different types of counters to do this.

Just add up the eligible zones.

Signed-off-by: Johannes Weiner <hannes@...xchg.org>
---
 mm/vmscan.c | 21 +++++----------------
 1 file changed, 5 insertions(+), 16 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1154b3a2b637..57f533b808f2 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -351,32 +351,21 @@ unsigned long zone_reclaimable_pages(struct zone *zone)
  */
 unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx)
 {
-	unsigned long lru_size = 0;
+	unsigned long size = 0;
 	int zid;
 
-	if (!mem_cgroup_disabled()) {
-		for (zid = 0; zid < MAX_NR_ZONES; zid++)
-			lru_size += mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
-	} else
-		lru_size = node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru);
-
-	for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) {
+	for (zid = 0; zid <= zone_idx; zid++) {
 		struct zone *zone = &lruvec_pgdat(lruvec)->node_zones[zid];
-		unsigned long size;
 
 		if (!managed_zone(zone))
 			continue;
 
 		if (!mem_cgroup_disabled())
-			size = mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
+			size += mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
 		else
-			size = zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zid],
-				       NR_ZONE_LRU_BASE + lru);
-		lru_size -= min(size, lru_size);
+			size += zone_page_state(zone, NR_ZONE_LRU_BASE + lru);
 	}
-
-	return lru_size;
-
+	return size;
 }
 
 /*
-- 
2.23.0