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Subject[PATCH v4 1/6] ACPI: NUMA: Up-level "map to online node" functionality
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The acpi_map_pxm_to_online_node() helper is used to find the closest
online node to a given proximity domain. This is used to map devices in
a proximity domain with no online memory or cpus to the closest online
node and populate a device's 'numa_node' property. The numa_node
property allows applications to be migrated "close" to a resource.

In preparation for providing a generic facility to optionally map an
address range to its closest online node, or the node the range would
represent were it to be onlined (target_node), up-level the core of
acpi_map_pxm_to_online_node() to a generic mm/numa helper.

Cc: Michal Hocko <mhocko@suse.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
drivers/acpi/numa/srat.c | 41 -----------------------------------------
include/linux/acpi.h | 23 ++++++++++++++++++++++-
include/linux/numa.h | 9 +++++++++
mm/mempolicy.c | 30 ++++++++++++++++++++++++++++++
4 files changed, 61 insertions(+), 42 deletions(-)

diff --git a/drivers/acpi/numa/srat.c b/drivers/acpi/numa/srat.c
index eadbf90e65d1..47b4969d9b93 100644
--- a/drivers/acpi/numa/srat.c
+++ b/drivers/acpi/numa/srat.c
@@ -72,47 +72,6 @@ int acpi_map_pxm_to_node(int pxm)
}
EXPORT_SYMBOL(acpi_map_pxm_to_node);

-/**
- * acpi_map_pxm_to_online_node - Map proximity ID to online node
- * @pxm: ACPI proximity ID
- *
- * This is similar to acpi_map_pxm_to_node(), but always returns an online
- * node. When the mapped node from a given proximity ID is offline, it
- * looks up the node distance table and returns the nearest online node.
- *
- * ACPI device drivers, which are called after the NUMA initialization has
- * completed in the kernel, can call this interface to obtain their device
- * NUMA topology from ACPI tables. Such drivers do not have to deal with
- * offline nodes. A node may be offline when a device proximity ID is
- * unique, SRAT memory entry does not exist, or NUMA is disabled, ex.
- * "numa=off" on x86.
- */
-int acpi_map_pxm_to_online_node(int pxm)
-{
- 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)) {
- int min_dist = INT_MAX, dist, n;
-
- for_each_online_node(n) {
- dist = node_distance(node, n);
- if (dist < min_dist) {
- min_dist = dist;
- min_node = n;
- }
- }
- }
-
- return min_node;
-}
-EXPORT_SYMBOL(acpi_map_pxm_to_online_node);
-
static void __init
acpi_table_print_srat_entry(struct acpi_subtable_header *header)
{
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 0f37a7d5fa77..69b73ecfbee4 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -401,9 +401,30 @@ extern void acpi_osi_setup(char *str);
extern bool acpi_osi_is_win8(void);

#ifdef CONFIG_ACPI_NUMA
-int acpi_map_pxm_to_online_node(int pxm);
int acpi_map_pxm_to_node(int pxm);
int acpi_get_node(acpi_handle handle);
+
+/**
+ * acpi_map_pxm_to_online_node - Map proximity ID to online node
+ * @pxm: ACPI proximity ID
+ *
+ * This is similar to acpi_map_pxm_to_node(), but always returns an online
+ * node. When the mapped node from a given proximity ID is offline, it
+ * looks up the node distance table and returns the nearest online node.
+ *
+ * ACPI device drivers, which are called after the NUMA initialization has
+ * completed in the kernel, can call this interface to obtain their device
+ * NUMA topology from ACPI tables. Such drivers do not have to deal with
+ * offline nodes. A node may be offline when a device proximity ID is
+ * unique, SRAT memory entry does not exist, or NUMA is disabled, ex.
+ * "numa=off" on x86.
+ */
+static inline int acpi_map_pxm_to_online_node(int pxm)
+{
+ int node = acpi_map_pxm_to_node(pxm);
+
+ return numa_map_to_online_node(node);
+}
#else
static inline int acpi_map_pxm_to_online_node(int pxm)
{
diff --git a/include/linux/numa.h b/include/linux/numa.h
index 110b0e5d0fb0..20f4e44b186c 100644
--- a/include/linux/numa.h
+++ b/include/linux/numa.h
@@ -13,4 +13,13 @@

#define NUMA_NO_NODE (-1)

+#ifdef CONFIG_NUMA
+int numa_map_to_online_node(int node);
+#else
+static inline int numa_map_to_online_node(int node)
+{
+ return NUMA_NO_NODE;
+}
+#endif
+
#endif /* _LINUX_NUMA_H */
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 067cf7d3daf5..4cff069279f6 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -127,6 +127,36 @@ static struct mempolicy default_policy = {

static struct mempolicy preferred_node_policy[MAX_NUMNODES];

+/**
+ * numa_map_to_online_node - Find closest online node
+ * @nid: Node id to start the search
+ *
+ * Lookup the next closest node by distance if @nid is not online.
+ */
+int numa_map_to_online_node(int node)
+{
+ int min_node;
+
+ if (node == NUMA_NO_NODE)
+ node = 0;
+
+ min_node = node;
+ if (!node_online(node)) {
+ int min_dist = INT_MAX, dist, n;
+
+ for_each_online_node(n) {
+ dist = node_distance(node, n);
+ if (dist < min_dist) {
+ min_dist = dist;
+ min_node = n;
+ }
+ }
+ }
+
+ return min_node;
+}
+EXPORT_SYMBOL_GPL(numa_map_to_online_node);
+
struct mempolicy *get_task_policy(struct task_struct *p)
{
struct mempolicy *pol = p->mempolicy;
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