[PATCH AUTOSEL 5.4 6/6] nvme: find numa distance only if controller has valid numa id

[Sasha Levin]

From: Nilay Shroff <nilay at linux.ibm.com>

[ Upstream commit 863fe60ed27f2c85172654a63c5b827e72c8b2e6 ]

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 at linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Sagi Grimberg <sagi at grimberg.me>
Reviewed-by: Chaitanya Kulkarni <kch at nvidia.com>
Signed-off-by: Keith Busch <kbusch at kernel.org>
Signed-off-by: Sasha Levin <sashal at kernel.org>
---
 drivers/nvme/host/multipath.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 811f7b96b5517..4f3220aef7c47 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -180,7 +180,8 @@ 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;
-- 
2.43.0