mm: memcontrol: cleanup css_reset callback

- Do not take memcg_limit_mutex for resetting limits - the cgroup cannot
  be altered from userspace anymore, so no need to protect them.

- Use plain page_counter_limit() for resetting ->memory and ->memsw
  limits instead of mem_cgrouop_resize_* helpers - we enlarge the limits,
  so no need in special handling.

- Reset ->swap and ->tcpmem limits as well.
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memcontrol.c

@@ -4257,9 +4257,11 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 
-	mem_cgroup_resize_limit(memcg, PAGE_COUNTER_MAX);
-	mem_cgroup_resize_memsw_limit(memcg, PAGE_COUNTER_MAX);
-	memcg_update_kmem_limit(memcg, PAGE_COUNTER_MAX);
+	page_counter_limit(&memcg->memory, PAGE_COUNTER_MAX);
+	page_counter_limit(&memcg->swap, PAGE_COUNTER_MAX);
+	page_counter_limit(&memcg->memsw, PAGE_COUNTER_MAX);
+	page_counter_limit(&memcg->kmem, PAGE_COUNTER_MAX);
+	page_counter_limit(&memcg->tcpmem, PAGE_COUNTER_MAX);
 	memcg->low = 0;
 	memcg->high = PAGE_COUNTER_MAX;
 	memcg->soft_limit = PAGE_COUNTER_MAX;