diff --git a/block/blk-mq-cpumap.c b/block/blk-mq-cpumap.c
index 0afa4dc483656d9dcef486680719ff7a73c2a7cd..f945621a0e8f2864a0829a84f1e8530236854bca 100644
--- a/block/blk-mq-cpumap.c
+++ b/block/blk-mq-cpumap.c
@@ -60,7 +60,11 @@ int blk_mq_map_queues(struct blk_mq_queue_map *qmap)
 }
 EXPORT_SYMBOL_GPL(blk_mq_map_queues);
 
-/*
+/**
+ * blk_mq_hw_queue_to_node - Look up the memory node for a hardware queue index
+ * @qmap: CPU to hardware queue map.
+ * @index: hardware queue index.
+ *
  * We have no quick way of doing reverse lookups. This is only used at
  * queue init time, so runtime isn't important.
  */