mm: memcontrol: fix percpu vmstats and vmevents flush

Instead of using raw_cpu_read() use per_cpu() to read the actual data of
the corresponding cpu otherwise we will be reading the data of the
current cpu for the number of online CPUs.

Link: http://lkml.kernel.org/r/20190829203110.129263-1-shakeelb@google.com
Fixes: bb65f89b ("mm: memcontrol: flush percpu vmevents before releasing memcg")
Fixes: c350a99e ("mm: memcontrol: flush percpu vmstats before releasing memcg")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memcontrol.c

@@ -3278,7 +3278,7 @@ static void memcg_flush_percpu_vmstats(struct mem_cgroup *memcg, bool slab_only)
 
 	for_each_online_cpu(cpu)
 		for (i = min_idx; i < max_idx; i++)
-			stat[i] += raw_cpu_read(memcg->vmstats_percpu->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++)
@@ -3296,8 +3296,8 @@ static void memcg_flush_percpu_vmstats(struct mem_cgroup *memcg, bool slab_only)
 
 		for_each_online_cpu(cpu)
 			for (i = min_idx; i < max_idx; i++)
-				stat[i] += raw_cpu_read(
-					pn->lruvec_stat_cpu->count[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++)
@@ -3316,8 +3316,8 @@ static void memcg_flush_percpu_vmevents(struct mem_cgroup *memcg)
 
 	for_each_online_cpu(cpu)
 		for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
-			events[i] += raw_cpu_read(
-				memcg->vmstats_percpu->events[i]);
+			events[i] += per_cpu(memcg->vmstats_percpu->events[i],
+					     cpu);
 
 	for (mi = memcg; mi; mi = parent_mem_cgroup(mi))
 		for (i = 0; i < NR_VM_EVENT_ITEMS; i++)