cgroup/cpuset: fix typos in comments

Change hierachy to hierarchy and unrechable to unreachable,
no functionality changed.
Signed-off-by: Lu Jialin <lujialin4@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

kernel/cgroup/cpuset.c

@@ -585,7 +585,7 @@ static int validate_change(struct cpuset *cur, struct cpuset *trial)
 
 	par = parent_cs(cur);
 
-	/* On legacy hiearchy, we must be a subset of our parent cpuset. */
+	/* On legacy hierarchy, we must be a subset of our parent cpuset. */
 	ret = -EACCES;
 	if (!is_in_v2_mode() && !is_cpuset_subset(trial, par))
 		goto out;
@@ -1726,7 +1726,7 @@ static void update_tasks_nodemask(struct cpuset *cs)
  * When configured nodemask is changed, the effective nodemasks of this cpuset
  * and all its descendants need to be updated.
  *
- * On legacy hiearchy, effective_mems will be the same with mems_allowed.
+ * On legacy hierarchy, effective_mems will be the same with mems_allowed.
  *
  * Called with cpuset_mutex held
  */
@@ -2500,7 +2500,7 @@ static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
 		BUG();
 	}
 
-	/* Unrechable but makes gcc happy */
+	/* Unreachable but makes gcc happy */
 	return 0;
 }