diff --git a/block/blk-iocost.c b/block/blk-iocost.c
index 0003bf2f3b304857be74c021a3170a7479798aa0..30dda16bb879127f73104547c41e571cd8d6bf4d 100644
--- a/block/blk-iocost.c
+++ b/block/blk-iocost.c
@@ -1306,6 +1306,13 @@ static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now)
 
 	lockdep_assert_held(&iocg->waitq.lock);
 
+	/*
+	 * If the delay is set by another CPU, we may be in the past. No need to
+	 * change anything if so. This avoids decay calculation underflow.
+	 */
+	if (time_before64(now->now, iocg->delay_at))
+		return false;
+
 	/* calculate the current delay in effect - 1/2 every second */
 	tdelta = now->now - iocg->delay_at;
 	if (iocg->delay)