diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index fb8b49437573..a06b45272411 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -594,49 +594,46 @@ static void root_cgroup_cputime(struct cgroup_base_stat *bstat)
 	}
 }
 
+
+static void cgroup_force_idle_show(struct seq_file *seq, struct cgroup_base_stat *bstat)
+{
+#ifdef CONFIG_SCHED_CORE
+	u64 forceidle_time = bstat->forceidle_sum;
+
+	do_div(forceidle_time, NSEC_PER_USEC);
+	seq_printf(seq, "core_sched.force_idle_usec %llu\n", forceidle_time);
+#endif
+}
+
 void cgroup_base_stat_cputime_show(struct seq_file *seq)
 {
 	struct cgroup *cgrp = seq_css(seq)->cgroup;
 	u64 usage, utime, stime;
-	struct cgroup_base_stat bstat;
-#ifdef CONFIG_SCHED_CORE
-	u64 forceidle_time;
-#endif
 
 	if (cgroup_parent(cgrp)) {
 		cgroup_rstat_flush_hold(cgrp);
 		usage = cgrp->bstat.cputime.sum_exec_runtime;
 		cputime_adjust(&cgrp->bstat.cputime, &cgrp->prev_cputime,
 			       &utime, &stime);
-#ifdef CONFIG_SCHED_CORE
-		forceidle_time = cgrp->bstat.forceidle_sum;
-#endif
 		cgroup_rstat_flush_release(cgrp);
 	} else {
-		root_cgroup_cputime(&bstat);
-		usage = bstat.cputime.sum_exec_runtime;
-		utime = bstat.cputime.utime;
-		stime = bstat.cputime.stime;
-#ifdef CONFIG_SCHED_CORE
-		forceidle_time = bstat.forceidle_sum;
-#endif
+		/* cgrp->bstat of root is not actually used, reuse it */
+		root_cgroup_cputime(&cgrp->bstat);
+		usage = cgrp->bstat.cputime.sum_exec_runtime;
+		utime = cgrp->bstat.cputime.utime;
+		stime = cgrp->bstat.cputime.stime;
 	}
 
 	do_div(usage, NSEC_PER_USEC);
 	do_div(utime, NSEC_PER_USEC);
 	do_div(stime, NSEC_PER_USEC);
-#ifdef CONFIG_SCHED_CORE
-	do_div(forceidle_time, NSEC_PER_USEC);
-#endif
 
 	seq_printf(seq, "usage_usec %llu\n"
 		   "user_usec %llu\n"
 		   "system_usec %llu\n",
 		   usage, utime, stime);
 
-#ifdef CONFIG_SCHED_CORE
-	seq_printf(seq, "core_sched.force_idle_usec %llu\n", forceidle_time);
-#endif
+	cgroup_force_idle_show(seq, &cgrp->bstat);
 }
 
 /* Add bpf kfuncs for cgroup_rstat_updated() and cgroup_rstat_flush() */