diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 43cff01a5a67..060c82222063 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1037,10 +1037,12 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
 		return -EBUSY;
 	}
 
+	mutex_lock(&nbd->config_lock);
 	socks = krealloc(config->socks, (config->num_connections + 1) *
 			 sizeof(struct nbd_sock *), GFP_KERNEL);
 	if (!socks) {
 		sockfd_put(sock);
+		mutex_unlock(&nbd->config_lock);
 		return -ENOMEM;
 	}
 
@@ -1049,6 +1051,7 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
 	nsock = kzalloc(sizeof(struct nbd_sock), GFP_KERNEL);
 	if (!nsock) {
 		sockfd_put(sock);
+		mutex_unlock(&nbd->config_lock);
 		return -ENOMEM;
 	}
 
@@ -1061,6 +1064,7 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
 	nsock->cookie = 0;
 	socks[config->num_connections++] = nsock;
 	atomic_inc(&config->live_connections);
+	mutex_unlock(&nbd->config_lock);
 
 	return 0;
 }