[RFC PATCH v5 06/14] mm/mglru: return for unavailable anon reclaim earlier

["Barry Song (Xiaomi)" <baohua@kernel.org>]

From: Kairui Song <kasong@tencent.com>

No feature change, just shuffle some code, prepare for later commits.

Signed-off-by: Kairui Song <kasong@tencent.com>
Signed-off-by: Barry Song (Xiaomi) <baohua@kernel.org>
---
 mm/vmscan.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index d3caed8aa789..0930bee5906e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -5215,20 +5215,6 @@ static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc,
 			   struct mem_cgroup *memcg, int swappiness)
 {
 	unsigned long nr_to_scan, evictable, sizes[ANON_AND_FILE];
-	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
-
-	/*
-	 * Proactive reclaim initiated by userspace for anonymous memory only.
-	 * SWAPPINESS_ANON_ONLY is set only on the proactive reclaim path, so
-	 * warn if it shows up elsewhere. When anon cannot be reclaimed (e.g.
-	 * no swap), return 0 to skip the scan entirely, avoiding useless scan
-	 * work when there is nothing eligible to reclaim.
-	 */
-	if (swappiness == SWAPPINESS_ANON_ONLY) {
-		WARN_ON_ONCE(!sc->proactive);
-		if (!can_reclaim_anon_pages(memcg, pgdat->node_id, sc))
-			return 0;
-	}
 
 	lruvec_evictable_size(lruvec, swappiness, sizes);
 	evictable = sizes[LRU_GEN_ANON] + sizes[LRU_GEN_FILE];
@@ -5285,6 +5271,19 @@ static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
 	int swappiness = get_swappiness(lruvec, sc);
 	struct mem_cgroup *memcg = lruvec_memcg(lruvec);
 
+	/*
+	 * Proactive reclaim initiated by userspace for anonymous memory only.
+	 * SWAPPINESS_ANON_ONLY is set only on the proactive reclaim path, so
+	 * warn if it shows up elsewhere. When anon cannot be reclaimed (e.g.
+	 * no swap), return 0 to skip the scan entirely, avoiding useless scan
+	 * work when there is nothing eligible to reclaim.
+	 */
+	if (swappiness == SWAPPINESS_ANON_ONLY) {
+		WARN_ON_ONCE(!sc->proactive);
+		if (!can_reclaim_anon_pages(memcg, lruvec_pgdat(lruvec)->node_id, sc))
+			return false;
+	}
+
 	nr_to_scan = get_nr_to_scan(lruvec, sc, memcg, swappiness);
 	while (nr_to_scan > 0) {
 		int delta;
-- 
2.34.1