nvme: find numa distance only if controller has valid numa id

On system where native nvme multipath is configured and iopolicy
is set to numa but the nvme controller numa node id is undefined
or -1 (NUMA_NO_NODE) then avoid calculating node distance for
finding optimal io path. In such case we may access numa distance
table with invalid index and that may potentially refer to incorrect
memory. So this patch ensures that if the nvme controller numa node
id is -1 then instead of calculating node distance for finding optimal
io path, we set the numa node distance of such controller to default 10
(LOCAL_DISTANCE).

Link: https://lore.kernel.org/all/20240413090614.678353-1-nilay@linux.ibm.com/
Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 5397fb428b242cea36f8c36997e134f6463e9f39..d16e976ae1a4732efef32a9da1da88be6567f621 100644 (file)
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -247,7 +247,8 @@ static struct nvme_ns *__nvme_find_path(struct nvme_ns_head *head, int node)
                if (nvme_path_is_disabled(ns))
                        continue;
 
-               if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_NUMA)
+               if (ns->ctrl->numa_node != NUMA_NO_NODE &&
+                   READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_NUMA)
                        distance = node_distance(node, ns->ctrl->numa_node);
                else
                        distance = LOCAL_DISTANCE;