acpi, numa: fix pxm to online numa node associations

BugLink: http://bugs.launchpad.net/bugs/1764973

commit dc9e0a93 upstream.

Commit 99759869 "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: 99759869 ("acpi: Add acpi_map_pxm_to_online_node()")
Cc: <stable@vger.kernel.org>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com&gt;>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

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);