cgroup: fix a failure path in create_css()

If online_css() fails, we should remove cgroup files belonging
to css->ss.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

kernel/cgroup.c

@@ -4112,17 +4112,17 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss)
 
 	err = percpu_ref_init(&css->refcnt, css_release);
 	if (err)
-		goto err_free;
+		goto err_free_css;
 
 	init_css(css, ss, cgrp);
 
 	err = cgroup_populate_dir(cgrp, 1 << ss->subsys_id);
 	if (err)
-		goto err_free;
+		goto err_free_percpu_ref;
 
 	err = online_css(css);
 	if (err)
-		goto err_free;
+		goto err_clear_dir;
 
 	dget(cgrp->dentry);
 	css_get(css->parent);
@@ -4138,8 +4138,11 @@ static int create_css(struct cgroup *cgrp, struct cgroup_subsys *ss)
 
 	return 0;
 
-err_free:
+err_clear_dir:
+	cgroup_clear_dir(css->cgroup, 1 << css->ss->subsys_id);
+err_free_percpu_ref:
 	percpu_ref_cancel_init(&css->refcnt);
+err_free_css:
 	ss->css_free(css);
 	return err;
 }