[Devel] [PATCH RHEL8 COMMIT] ms/mm: vmscan: turn shrink_node_memcg() into shrink_lruvec()

[Konstantin Khorenko]

The commit is pushed to "branch-rh8-4.18.0-80.1.2.vz8.3.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-80.1.2.vz8.3.4
------>
commit f3044ee66ea33026a4f070923709bcf6473ad437
Author: Johannes Weiner <hannes at cmpxchg.org>
Date:   Thu Apr 2 16:02:58 2020 +0300

    ms/mm: vmscan: turn shrink_node_memcg() into shrink_lruvec()
    
    An lruvec holds LRU pages owned by a certain NUMA node and cgroup.
    Instead of awkwardly passing around a combination of a pgdat and a memcg
    pointer, pass down the lruvec as soon as we can look it up.
    
    Nested callers that need to access node or cgroup properties can look them
    them up if necessary, but there are only a few cases.
    
    Link: http://lkml.kernel.org/r/20191022144803.302233-7-hannes@cmpxchg.org
    Signed-off-by: Johannes Weiner <hannes at cmpxchg.org>
    Reviewed-by: Roman Gushchin <guro at fb.com>
    Reviewed-by: Shakeel Butt <shakeelb at google.com>
    Acked-by: Michal Hocko <mhocko at suse.com>
    Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
    
    (cherry picked from commit afaf07a65ddbdd70871cc3b81463f2a8f3884b6f)
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 mm/vmscan.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index e12bd53b846f..2b443e6f5bc3 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2086,9 +2086,10 @@ enum scan_balance {
  * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan
  * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan
  */
-static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
-			   struct scan_control *sc, unsigned long *nr)
+static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
+			   unsigned long *nr)
 {
+	struct mem_cgroup *memcg = lruvec_memcg(lruvec);
 	int swappiness = mem_cgroup_swappiness(memcg);
 	struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
 	u64 fraction[2];
@@ -2284,10 +2285,8 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 /*
  * This is a basic per-node page freer.  Used by both kswapd and direct reclaim.
  */
-static void shrink_node_memcg(struct pglist_data *pgdat, struct mem_cgroup *memcg,
-			      struct scan_control *sc)
+static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
 {
-	struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
 	unsigned long nr[NR_LRU_LISTS];
 	unsigned long targets[NR_LRU_LISTS];
 	unsigned long nr_to_scan;
@@ -2297,7 +2296,7 @@ static void shrink_node_memcg(struct pglist_data *pgdat, struct mem_cgroup *memc
 	struct blk_plug plug;
 	bool scan_adjusted;
 
-	get_scan_count(lruvec, memcg, sc, nr);
+	get_scan_count(lruvec, sc, nr);
 
 	/* Record the original scan target for proportional adjustments later */
 	memcpy(targets, nr, sizeof(nr));
@@ -2510,7 +2509,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 
 	memcg = mem_cgroup_iter(root, NULL, &reclaim);
 	do {
-		unsigned long lru_pages;
+		struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
 		unsigned long reclaimed;
 		unsigned long scanned;
 
@@ -2540,7 +2539,8 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 
 		reclaimed = sc->nr_reclaimed;
 		scanned = sc->nr_scanned;
-		shrink_node_memcg(pgdat, memcg, sc, &lru_pages);
+
+		shrink_lruvec(lruvec, sc);
 
 		if (memcg)
 			shrink_slab(sc->gfp_mask, pgdat->node_id,
@@ -3059,6 +3059,7 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
 						pg_data_t *pgdat,
 						unsigned long *nr_scanned)
 {
+	struct lruvec *lruvec = mem_cgroup_lruvec(memcg, pgdat);
 	struct scan_control sc = {
 		.nr_to_reclaim = SWAP_CLUSTER_MAX,
 		.target_mem_cgroup = memcg,
@@ -3083,7 +3084,7 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
 	 * will pick up pages from other mem cgroup's as well. We hack
 	 * the priority and make it zero.
 	 */
-	shrink_node_memcg(pgdat, memcg, &sc);
+	shrink_lruvec(lruvec, &sc);
 
 	trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);