diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index fa856b2ca7af0316222891d65a94a1b4f52ba13d..0363ab534c8e61f1aee6c2f8f78fa4283a3c0288 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -662,6 +662,11 @@ static const struct block_device_operations bcache_ops = {
 void bcache_device_stop(struct bcache_device *d)
 {
 	if (!test_and_set_bit(BCACHE_DEV_CLOSING, &d->flags))
+		/*
+		 * closure_fn set to
+		 * - cached device: cached_dev_flush()
+		 * - flash dev: flash_dev_flush()
+		 */
 		closure_queue(&d->cl);
 }
 
@@ -1675,6 +1680,7 @@ static void __cache_set_unregister(struct closure *cl)
 void bch_cache_set_stop(struct cache_set *c)
 {
 	if (!test_and_set_bit(CACHE_SET_STOPPING, &c->flags))
+		/* closure_fn set to __cache_set_unregister() */
 		closure_queue(&c->caching);
 }