diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index f9797b2..87ea95d 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -504,8 +504,9 @@
  *
  * This function invokes @prfill on each blkg of @blkcg if pd for the
  * policy specified by @pol exists.  @prfill is invoked with @sf, the
- * policy data and @data.  If @show_total is %true, the sum of the return
- * values from @prfill is printed with "Total" label at the end.
+ * policy data and @data and the matching queue lock held.  If @show_total
+ * is %true, the sum of the return values from @prfill is printed with
+ * "Total" label at the end.
  *
  * This is to be used to construct print functions for
  * cftype->read_seq_string method.
@@ -520,11 +521,14 @@
 	struct hlist_node *n;
 	u64 total = 0;
 
-	spin_lock_irq(&blkcg->lock);
-	hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node)
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
+		spin_lock_irq(blkg->q->queue_lock);
 		if (blkcg_policy_enabled(blkg->q, pol))
 			total += prfill(sf, blkg->pd[pol->plid], data);
-	spin_unlock_irq(&blkcg->lock);
+		spin_unlock_irq(blkg->q->queue_lock);
+	}
+	rcu_read_unlock();
 
 	if (show_total)
 		seq_printf(sf, "Total %llu\n", (unsigned long long)total);