[PATCH 3/3] mm/vmscan: consolidate promo vs. high watermark checks

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

There are three sites which all 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 patern into a helper function. While at it, remove the
include for <linux/sched/sysctl.h> in mm/page_alloc.c now that the
dependency on sysctl_numa_balancing_mode has been abstracted into
vmscan code.

No functional changes intended.

Signed-off-by: Joshua Hahn <joshua.hahnjy@gmail.com>
---
 mm/internal.h   |  1 +
 mm/page_alloc.c |  6 +-----
 mm/vmscan.c     | 22 +++++++++++++---------
 3 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index 566cbd2dce485..8beb5b263ca1f 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/page_alloc.c b/mm/page_alloc.c
index 2fe49f3c0de13..6d6da844f4b76 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -45,7 +45,6 @@
 #include <linux/mmu_notifier.h>
 #include <linux/migrate.h>
 #include <linux/sched/mm.h>
-#include <linux/sched/sysctl.h>
 #include <linux/page_owner.h>
 #include <linux/page_table_check.h>
 #include <linux/memcontrol.h>
@@ -3801,10 +3800,7 @@ static bool should_skip_kswapd_zone(struct zone *zone, unsigned int order,
 	if (waitqueue_active(&zone->zone_pgdat->kswapd_wait))
 		return false;
 
-	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);
 	return !zone_watermark_fast(zone, order, mark, ac->highest_zoneidx, 0);
 }
 
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9959ca158ce83..9af50783fc824 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -478,6 +478,17 @@ 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;
@@ -5212,7 +5223,6 @@ 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;
@@ -5224,12 +5234,9 @@ 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;
@@ -7131,10 +7138,7 @@ 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
-- 
2.53.1-Meta