[PATCH] Add populated_map to account for memoryless nodes

[Nishanth Aravamudan <nacc@us.ibm.com>]

Split up Lee and Anton's original patch
(http://marc.info/?l=linux-mm&m=118133042025995&w=2), to allow for the
populated_map changes to go in on their own.

Add a populated_map nodemask to indicate a node has memory or not. We
have run into a number of issues (in practice and in code) with
assumptions about every node having memory. Having this nodemask allows
us to fix these issues; in particular, THISNODE allocations will come
from the node specified, only, and the INTERLEAVE policy will be able to
do the right thing with memoryless nodes.

Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>

---

Andrew, sorry, typo'd your address in the previous series. Will be
sending them out again, anyways...

diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
index 52c54a5..751d3d7 100644
--- a/include/linux/nodemask.h
+++ b/include/linux/nodemask.h
@@ -64,12 +64,16 @@
  *
  * int node_online(node)		Is some node online?
  * int node_possible(node)		Is some node possible?
+ * int node_populated(node)		Is some node populated [at policy_zone]
  *
  * int any_online_node(mask)		First online node in mask
  *
  * node_set_online(node)		set bit 'node' in node_online_map
  * node_set_offline(node)		clear bit 'node' in node_online_map
  *
+ * node_set_populated(node)		set bit 'node' in node_populated_map
+ * node_not_populated(node)		clear bit 'node' in node_populated_map
+ *
  * for_each_node(node)			for-loop node over node_possible_map
  * for_each_online_node(node)		for-loop node over node_online_map
  *
@@ -344,12 +348,14 @@ static inline void __nodes_remap(nodemask_t *dstp, const nodemask_t *srcp,
 
 extern nodemask_t node_online_map;
 extern nodemask_t node_possible_map;
+extern nodemask_t node_populated_map;
 
 #if MAX_NUMNODES > 1
 #define num_online_nodes()	nodes_weight(node_online_map)
 #define num_possible_nodes()	nodes_weight(node_possible_map)
 #define node_online(node)	node_isset((node), node_online_map)
 #define node_possible(node)	node_isset((node), node_possible_map)
+#define node_populated(node)	node_isset((node), node_populated_map)
 #define first_online_node	first_node(node_online_map)
 #define next_online_node(nid)	next_node((nid), node_online_map)
 extern int nr_node_ids;
@@ -358,6 +364,7 @@ extern int nr_node_ids;
 #define num_possible_nodes()	1
 #define node_online(node)	((node) == 0)
 #define node_possible(node)	((node) == 0)
+#define node_populated(node)	((node) == 0)
 #define first_online_node	0
 #define next_online_node(nid)	(MAX_NUMNODES)
 #define nr_node_ids		1
@@ -375,6 +382,9 @@ extern int nr_node_ids;
 #define node_set_online(node)	   set_bit((node), node_online_map.bits)
 #define node_set_offline(node)	   clear_bit((node), node_online_map.bits)
 
+#define node_set_populated(node)   set_bit((node), node_populated_map.bits)
+#define node_not_populated(node)   clear_bit((node), node_populated_map.bits)
+
 #define for_each_node(node)	   for_each_node_mask((node), node_possible_map)
 #define for_each_online_node(node) for_each_node_mask((node), node_online_map)
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 07cd5ae..8eea4ff 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -54,6 +54,9 @@ nodemask_t node_online_map __read_mostly = { { [0] = 1UL } };
 EXPORT_SYMBOL(node_online_map);
 nodemask_t node_possible_map __read_mostly = NODE_MASK_ALL;
 EXPORT_SYMBOL(node_possible_map);
+nodemask_t node_populated_map __read_mostly = NODE_MASK_NONE;
+EXPORT_SYMBOL(node_populated_map);
+
 unsigned long totalram_pages __read_mostly;
 unsigned long totalreserve_pages __read_mostly;
 long nr_swap_pages;
@@ -2161,7 +2164,7 @@ static int node_order[MAX_NUMNODES];
 static void build_zonelists_in_zone_order(pg_data_t *pgdat, int nr_nodes)
 {
 	enum zone_type i;
-	int pos, j, node;
+	int pos, j;
 	int zone_type;		/* needs to be signed */
 	struct zone *z;
 	struct zonelist *zonelist;
@@ -2171,7 +2174,7 @@ static void build_zonelists_in_zone_order(pg_data_t *pgdat, int nr_nodes)
 		pos = 0;
 		for (zone_type = i; zone_type >= 0; zone_type--) {
 			for (j = 0; j < nr_nodes; j++) {
-				node = node_order[j];
+				int node = node_order[j];
 				z = &NODE_DATA(node)->node_zones[zone_type];
 				if (populated_zone(z)) {
 					zonelist->zones[pos++] = z;
@@ -2244,6 +2247,22 @@ static void set_zonelist_order(void)
 		current_zonelist_order = user_zonelist_order;
 }
 
+/*
+ * setup_populate_map() - record nodes whose "policy_zone" is "on-node".
+ */
+static void setup_populated_map(int nid)
+{
+	pg_data_t *pgdat = NODE_DATA(nid);
+	struct zonelist *zl = pgdat->node_zonelists + policy_zone;
+	struct zone *z = zl->zones[0];
+
+	VM_BUG_ON(!z);
+	if (z->zone_pgdat == pgdat)
+		node_set_populated(nid);
+	else
+		node_not_populated(nid);
+}
+
 static void build_zonelists(pg_data_t *pgdat)
 {
 	int j, node, load;
@@ -2327,6 +2346,15 @@ static void set_zonelist_order(void)
 	current_zonelist_order = ZONELIST_ORDER_ZONE;
 }
 
+/*
+ * setup_populated_map - non-NUMA case
+ * Only node 0 should be on-line, and it MUST be populated!
+ */
+static void setup_populated_map(int nid)
+{
+	node_set_populated(nid);
+}
+
 static void build_zonelists(pg_data_t *pgdat)
 {
 	int node, local_node;
@@ -2381,6 +2409,7 @@ static int __build_all_zonelists(void *dummy)
 	for_each_online_node(nid) {
 		build_zonelists(NODE_DATA(nid));
 		build_zonelist_cache(NODE_DATA(nid));
+		setup_populated_map(nid);
 	}
 	return 0;
 }

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