Re: [PATCH] acpi, numa: fix pxm to online numa node associations

Dan Williams
2018-03-17T01:16:41Z

[ adding Toshi's correct address ]

On Thu, Mar 15, 2018 at 8:08 PM, Dan Williams <dan.j.williams@intel.com> wrote:
> Commit 99759869faf1 "acpi: Add acpi_map_pxm_to_online_node()" added
> support for mapping a given proximity to its nearest, by SLIT distance,
> online node. However, it sometimes returns unexpected results due to the
> fact that it switches from comparing the PXM node to the last node that
> was closer than the current max.
>
> for_each_online_node(n) {
> dist = node_distance(node, n);
> if (dist < min_dist) {
> min_dist = dist;
> node = n; <---- from this point we're using the
> wrong node for node_distance()
>
>
> Fixes: 99759869faf1 ("acpi: Add acpi_map_pxm_to_online_node()")
> Cc: <stable@vger.kernel.org>
> Cc: Toshi Kani <toshi.kani@hp.com>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> Rafael, I can take this through the nvdimm tree with your ack. I have a
> few other nvdimm fixes pending for 4.16.
>
> drivers/acpi/numa.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
> index 8ccaae3550d2..85167603b9c9 100644
> --- a/drivers/acpi/numa.c
> +++ b/drivers/acpi/numa.c
> @@ -103,25 +103,27 @@ int acpi_map_pxm_to_node(int pxm)
> */
> int acpi_map_pxm_to_online_node(int pxm)
> {
> - int node, n, dist, min_dist;
> + int node, min_node;
>
> node = acpi_map_pxm_to_node(pxm);
>
> if (node == NUMA_NO_NODE)
> node = 0;
>
> + min_node = node;
> if (!node_online(node)) {
> - min_dist = INT_MAX;
> + int min_dist = INT_MAX, dist, n;
> +
> for_each_online_node(n) {
> dist = node_distance(node, n);
> if (dist < min_dist) {
> min_dist = dist;
> - node = n;
> + min_node = n;
> }
> }
> }
>
> - return node;
> + return min_node;
> }
> EXPORT_SYMBOL(acpi_map_pxm_to_online_node);
>
>