diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 5e65dc6def7e..764e0e155ae2 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -3861,7 +3861,7 @@ static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
 		/* now write out any block on a failed drive,
 		 * or P or Q if they were recomputed
 		 */
-		BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
+		dev = NULL;
 		if (s->failed == 2) {
 			dev = &sh->dev[s->failed_num[1]];
 			s->locked++;
@@ -3886,6 +3886,14 @@ static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
 			set_bit(R5_LOCKED, &dev->flags);
 			set_bit(R5_Wantwrite, &dev->flags);
 		}
+		if (WARN_ONCE(dev && !test_bit(R5_UPTODATE, &dev->flags),
+			      "%s: disk%td not up to date\n",
+			      mdname(conf->mddev),
+			      dev - (struct r5dev *) &sh->dev)) {
+			clear_bit(R5_LOCKED, &dev->flags);
+			clear_bit(R5_Wantwrite, &dev->flags);
+			s->locked--;
+		}
 		clear_bit(STRIPE_DEGRADED, &sh->state);
 
 		set_bit(STRIPE_INSYNC, &sh->state);