[PATCH v6 15/17] mm: Generalize shrink_slab() calls in shrink_node()

[Kirill Tkhai <ktkhai@virtuozzo.com>]

From: Vladimir Davydov <vdavydov.dev@gmail.com>

The patch makes shrink_slab() be called for root_mem_cgroup
in the same way as it's called for the rest of cgroups.
This simplifies the logic and improves the readability.

Signed-off-by: Vladimir Davydov <vdavydov.dev@gmail.com>
ktkhai: Description written.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
 mm/vmscan.c |   13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2fbf3b476601..f1d23e2df988 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -661,9 +661,6 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
 			.memcg = memcg,
 		};
 
-		if (!!memcg != !!(shrinker->flags & SHRINKER_MEMCG_AWARE))
-			continue;
-
 		if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
 			sc.nid = 0;
 
@@ -693,6 +690,7 @@ void drop_slab_node(int nid)
 		struct mem_cgroup *memcg = NULL;
 
 		freed = 0;
+		memcg = mem_cgroup_iter(NULL, NULL, NULL);
 		do {
 			freed += shrink_slab(GFP_KERNEL, nid, memcg, 0);
 		} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
@@ -2712,9 +2710,8 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 			shrink_node_memcg(pgdat, memcg, sc, &lru_pages);
 			node_lru_pages += lru_pages;
 
-			if (memcg)
-				shrink_slab(sc->gfp_mask, pgdat->node_id,
-					    memcg, sc->priority);
+			shrink_slab(sc->gfp_mask, pgdat->node_id,
+				    memcg, sc->priority);
 
 			/* Record the group's reclaim efficiency */
 			vmpressure(sc->gfp_mask, memcg, false,
@@ -2738,10 +2735,6 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 			}
 		} while ((memcg = mem_cgroup_iter(root, memcg, &reclaim)));
 
-		if (global_reclaim(sc))
-			shrink_slab(sc->gfp_mask, pgdat->node_id, NULL,
-				    sc->priority);
-
 		if (reclaim_state) {
 			sc->nr_reclaimed += reclaim_state->reclaimed_slab;
 			reclaim_state->reclaimed_slab = 0;