diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 3d5271a7a849..40259c38d66a 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -897,6 +897,9 @@ static int pci_register_host_bridge(struct pci_host_bridge *bridge)
 	else
 		pr_info("PCI host bridge to bus %s\n", name);
 
+	if (nr_node_ids > 1 && pcibus_to_node(bus) == NUMA_NO_NODE)
+		dev_warn(&bus->dev, "Unknown NUMA node; performance will be reduced\n");
+
 	/* Add initial resources to the bus */
 	resource_list_for_each_entry_safe(window, n, &resources) {
 		list_move_tail(&window->node, &bridge->windows);