mm: workingset: make shadow node shrinker memcg aware

Workingset code was recently made memcg aware, but shadow node shrinker
is still global.  As a result, one small cgroup can consume all memory
available for shadow nodes, possibly hurting other cgroups by reclaiming
their shadow nodes, even though reclaim distances stored in its shadow
nodes have no effect.  To avoid this, we need to make shadow node
shrinker memcg aware.

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/workingset.c b/mm/workingset.c
index 68e8cd9..8a75f8d 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -349,8 +349,12 @@
 	shadow_nodes = list_lru_shrink_count(&workingset_shadow_nodes, sc);
 	local_irq_enable();
 
-	pages = node_page_state(sc->nid, NR_ACTIVE_FILE) +
-		node_page_state(sc->nid, NR_INACTIVE_FILE);
+	if (memcg_kmem_enabled())
+		pages = mem_cgroup_node_nr_lru_pages(sc->memcg, sc->nid,
+						     LRU_ALL_FILE);
+	else
+		pages = node_page_state(sc->nid, NR_ACTIVE_FILE) +
+			node_page_state(sc->nid, NR_INACTIVE_FILE);
 
 	/*
 	 * Active cache pages are limited to 50% of memory, and shadow
@@ -460,7 +464,7 @@
 	.count_objects = count_shadow_nodes,
 	.scan_objects = scan_shadow_nodes,
 	.seeks = DEFAULT_SEEKS,
-	.flags = SHRINKER_NUMA_AWARE,
+	.flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE,
 };
 
 /*