Merge branch 'topic/user-access-begin' into next

Merge the user_access_begin() series from Christophe. This is based on
a commit from Linus that went into v5.5-rc7.

1 files changed, 9 insertions, 28 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c5b5f74cfd4d..6c83cf4ed970 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3287,49 +3287,34 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
 	}
 }
 
-static void memcg_flush_percpu_vmstats(struct mem_cgroup *memcg, bool slab_only)
+static void memcg_flush_percpu_vmstats(struct mem_cgroup *memcg)
 {
-	unsigned long stat[MEMCG_NR_STAT];
+	unsigned long stat[MEMCG_NR_STAT] = {0};
 	struct mem_cgroup *mi;
 	int node, cpu, i;
-	int min_idx, max_idx;
-
-	if (slab_only) {
-		min_idx = NR_SLAB_RECLAIMABLE;
-		max_idx = NR_SLAB_UNRECLAIMABLE;
-	} else {
-		min_idx = 0;
-		max_idx = MEMCG_NR_STAT;
-	}
-
-	for (i = min_idx; i < max_idx; i++)
-		stat[i] = 0;
 
 	for_each_online_cpu(cpu)
-		for (i = min_idx; i < max_idx; i++)
+		for (i = 0; i < MEMCG_NR_STAT; i++)
 			stat[i] += per_cpu(memcg->vmstats_percpu->stat[i], cpu);
 
 	for (mi = memcg; mi; mi = parent_mem_cgroup(mi))
-		for (i = min_idx; i < max_idx; i++)
+		for (i = 0; i < MEMCG_NR_STAT; i++)
 			atomic_long_add(stat[i], &mi->vmstats[i]);
 
-	if (!slab_only)
-		max_idx = NR_VM_NODE_STAT_ITEMS;
-
 	for_each_node(node) {
 		struct mem_cgroup_per_node *pn = memcg->nodeinfo[node];
 		struct mem_cgroup_per_node *pi;
 
-		for (i = min_idx; i < max_idx; i++)
+		for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
 			stat[i] = 0;
 
 		for_each_online_cpu(cpu)
-			for (i = min_idx; i < max_idx; i++)
+			for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
 				stat[i] += per_cpu(
 					pn->lruvec_stat_cpu->count[i], cpu);
 
 		for (pi = pn; pi; pi = parent_nodeinfo(pi, node))
-			for (i = min_idx; i < max_idx; i++)
+			for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
 				atomic_long_add(stat[i], &pi->lruvec_stat[i]);
 	}
 }
@@ -3403,13 +3388,9 @@ static void memcg_offline_kmem(struct mem_cgroup *memcg)
 		parent = root_mem_cgroup;
 
 	/*
-	 * Deactivate and reparent kmem_caches. Then flush percpu
-	 * slab statistics to have precise values at the parent and
-	 * all ancestor levels. It's required to keep slab stats
-	 * accurate after the reparenting of kmem_caches.
+	 * Deactivate and reparent kmem_caches.
 	 */
 	memcg_deactivate_kmem_caches(memcg, parent);
-	memcg_flush_percpu_vmstats(memcg, true);
 
 	kmemcg_id = memcg->kmemcg_id;
 	BUG_ON(kmemcg_id < 0);
@@ -4913,7 +4894,7 @@ static void mem_cgroup_free(struct mem_cgroup *memcg)
 	 * Flush percpu vmstats and vmevents to guarantee the value correctness
 	 * on parent's and all ancestor levels.
 	 */
-	memcg_flush_percpu_vmstats(memcg, false);
+	memcg_flush_percpu_vmstats(memcg);
 	memcg_flush_percpu_vmevents(memcg);
 	__mem_cgroup_free(memcg);
 }