[PATCHv3] nvme: find numa distance only if controller has valid numa id

[PATCHv3] nvme: find numa distance only if controller has valid numa id

[Nilay Shroff]

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>
---
Changes from v2:
	Formatting cleanups to avoid overshooting 80 chars width (Chaitanya)
Changes from v1:
    Formatting cleanups (Christoph)

 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 5397fb428b24..d16e976ae1a4 100644
--- 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;
-- 
2.44.0

Re: [PATCHv3] nvme: find numa distance only if controller has valid numa id

[Chaitanya Kulkarni]

On 4/16/2024 1:19 AM, Nilay Shroff wrote:
> 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: Chaitanya Kulkarni <kch@nvidia.com>

-ck

Re: [PATCHv3] nvme: find numa distance only if controller has valid numa id

[Sagi Grimberg]

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>

Re: [PATCHv3] nvme: find numa distance only if controller has valid numa id

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCHv3] nvme: find numa distance only if controller has valid numa id

[Keith Busch]

On Tue, Apr 16, 2024 at 01:49:23PM +0530, Nilay Shroff wrote:
> 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).

Thanks, applied to nvme-6.9.