ANDROID: Export memcg functions to allow module to add new files

Export cgroup_add_legacy_cftypes and a helper function to allow vendor module to expose additional files in the memory cgroup hierarchy.

Bug: 192052083

Signed-off-by: Liujie Xie <xieliujie@oppo.com>
Change-Id: Ie2b936b3e77c7ab6d740d1bb6d70e03c70a326a7
(cherry picked from commit f41a95eadca98506e627b21f5cc73332bba4d95c)

kernel/cgroup/cgroup.c

@@ -4511,6 +4511,7 @@ int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
 		cft->flags |= __CFTYPE_NOT_ON_DFL;
 	return cgroup_add_cftypes(ss, cfts);
 }
+EXPORT_SYMBOL_GPL(cgroup_add_legacy_cftypes);
 
 /**
  * cgroup_file_notify - generate a file modified event for a cgroup_file

mm/memcontrol.c

@@ -3415,6 +3415,7 @@ struct mem_cgroup *mem_cgroup_from_id(unsigned short id)
 	WARN_ON_ONCE(!rcu_read_lock_held());
 	return xa_load(&mem_cgroup_ids, id);
 }
+EXPORT_SYMBOL_GPL(mem_cgroup_from_id);
 
 #ifdef CONFIG_SHRINKER_DEBUG
 struct mem_cgroup *mem_cgroup_get_from_ino(unsigned long ino)