diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 3f858de9e9602fcc0f175a84316b0d96ff5c7f41..10a258f6ce13a6c15798f8ae7e3fa30dc8fd2567 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1612,8 +1612,13 @@ static void cache_set_flush(struct closure *cl)
 		mutex_unlock(&b->write_lock);
 	}
 
+	/*
+	 * If the register_cache_set() call to bch_cache_set_alloc() failed,
+	 * ca has not been assigned a value and return error.
+	 * So we need check ca is not NULL during bch_cache_set_unregister().
+	 */
 	for_each_cache(ca, c, i)
-		if (ca->alloc_thread)
+		if (ca && ca->alloc_thread)
 			kthread_stop(ca->alloc_thread);
 
 	if (c->journal.cur) {