diff --git a/fs/filescontrol.c b/fs/filescontrol.c
index 44ad9ef44e20ed45919ca60d06abbeb7f6bda80b..1d2d29127fd4dcbac82c7ae8e8ce7cde09189598 100644
--- a/fs/filescontrol.c
+++ b/fs/filescontrol.c
@@ -293,18 +293,16 @@ struct cgroup_subsys files_cgrp_subsys = {
 	.dfl_cftypes = files,
 };
 
+/*
+ * It could race against cgroup migration of current task, and
+ * using task_get_css() to get a valid css.
+ */
 void files_cgroup_assign(struct files_struct *files)
 {
-	struct task_struct *tsk = current;
 	struct cgroup_subsys_state *css;
-	struct cgroup *cgrp;
 
-	task_lock(tsk);
-	cgrp = task_cgroup(tsk, files_cgrp_id);
-	css = cgroup_subsys_state(cgrp, files_cgrp_id);
-	css_get(css);
+	css = task_get_css(current, files_cgrp_id);
 	files->files_cgroup = container_of(css, struct files_cgroup, css);
-	task_unlock(tsk);
 }
 
 void files_cgroup_remove(struct files_struct *files)
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index f3e50549e41c351270df016c9f7aa5937e829cf4..ca51b2c15bcc6d0e03120856b8128ae748806eda 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -416,12 +416,6 @@ static inline void cgroup_put(struct cgroup *cgrp)
 	css_put(&cgrp->self);
 }
 
-static inline struct cgroup_subsys_state *cgroup_subsys_state(
-	struct cgroup *cgrp, int subsys_id)
-{
-	return cgrp->subsys[subsys_id];
-}
-
 /**
  * task_css_set_check - obtain a task's css_set with extra access conditions
  * @task: the task to obtain css_set for