diff --git a/include/linux/sched.h b/include/linux/sched.h
index d35d2b6..3f1c088 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -418,6 +418,7 @@ struct cpu_itimer {
 struct cputime {
 	cputime_t utime;
 	cputime_t stime;
+	cputime_t rtime;
 };
 
 /**
diff --git a/kernel/fork.c b/kernel/fork.c
index 1766d32..d67c219 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1235,6 +1235,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 	p->utimescaled = p->stimescaled = 0;
 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
 	p->prev_cputime.utime = p->prev_cputime.stime = 0;
+	p->prev_cputime.rtime = 0;
 #endif
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
 	seqlock_init(&p->vtime_seqlock);
diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index ed12cbb..146e5f1 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -560,6 +560,9 @@ static void cputime_adjust(struct task_cputime *curr,
 	 */
 	rtime = nsecs_to_cputime(curr->sum_exec_runtime);
 
+	WARN_ON(prev->rtime > rtime);
+	prev->rtime = rtime;
+
 	if (total)
 		stime = scale_stime(stime, rtime, total);
 	else