acpi, numa: fix pxm to online numa node associations

BugLink: http://bugs.launchpad.net/bugs/1759655
commit dc9e0a9347e932e3fd3cd03e7ff241022ed6ea8a upstream.

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>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/drivers/acpi/numa.c b/drivers/acpi/numa.c
index 917f1cc0fda4c2f6c8cc64f7b90dc252a264ac7a..8fb74d9011da8fc201d6d5afd072bd801c9daf8e 100644 (file)
--- 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);