[PATCH 1/2] mm/vmscan: consolidate promo vs. high watermark checks

[Joshua Hahn <joshua.hahnjy@gmail.com>]

should_abort_scan() and pgdat_balanced() both check the watermark that
kswapd reclaims zones up to, which is the promo watermark when NUMA
balancing memory tiering is enabled, and the high watermark otherwise.

Consolidate the pattern into a helper function.

No functional changes intended.

Signed-off-by: Joshua Hahn <joshua.hahnjy@gmail.com>
---
 mm/internal.h |  1 +
 mm/vmscan.c   | 22 +++++++++++++---------
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 78a7f17b9934f..66495845ec058 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -68,6 +68,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 				gfp_t gfp_mask, const nodemask_t *mask);
 unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru,
 			      int zone_idx);
+unsigned long kswapd_wmark_pages(const struct zone *zone);
 
 #define MEMCG_RECLAIM_MAY_SWAP (1 << 1)
 #define MEMCG_RECLAIM_PROACTIVE (1 << 2)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 071a6eaef1a1a..97c5843e14f15 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -371,6 +371,17 @@ unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone
 	return size;
 }
 
+/*
+ * The watermark kswapd reclaims zones up to. With NUMA balancing memory
+ * tiering, kswapd keeps room above the high watermark for promotions.
+ */
+unsigned long kswapd_wmark_pages(const struct zone *zone)
+{
+	if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING)
+		return promo_wmark_pages(zone);
+	return high_wmark_pages(zone);
+}
+
 static unsigned long drop_slab_node(int nid)
 {
 	unsigned long freed = 0;
@@ -5049,7 +5060,6 @@ static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc,
 static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc)
 {
 	int i;
-	enum zone_watermarks mark;
 
 	if (unlikely(sc->proactive && signal_pending(current)))
 		return true;
@@ -5061,12 +5071,9 @@ static bool should_abort_scan(struct lruvec *lruvec, struct scan_control *sc)
 	if (!current_is_kswapd() || sc->order)
 		return false;
 
-	mark = sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING ?
-	       WMARK_PROMO : WMARK_HIGH;
-
 	for (i = 0; i <= sc->reclaim_idx; i++) {
 		struct zone *zone = lruvec_pgdat(lruvec)->node_zones + i;
-		unsigned long size = wmark_pages(zone, mark) + MIN_LRU_BATCH;
+		unsigned long size = kswapd_wmark_pages(zone) + MIN_LRU_BATCH;
 
 		if (managed_zone(zone) && !zone_watermark_ok(zone, 0, size, sc->reclaim_idx, 0))
 			return false;
@@ -6966,10 +6973,7 @@ static bool pgdat_balanced(pg_data_t *pgdat, int order, int highest_zoneidx)
 		enum zone_stat_item item;
 		unsigned long free_pages;
 
-		if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING)
-			mark = promo_wmark_pages(zone);
-		else
-			mark = high_wmark_pages(zone);
+		mark = kswapd_wmark_pages(zone);
 
 		/*
 		 * In defrag_mode, watermarks must be met in whole
-- 
2.53.0-Meta