1 files changed, 121 insertions, 85 deletions

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 1c84b48def20..5db322c9cb3f 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1492,8 +1492,6 @@ static int			sched_domains_curr_level;
 int				sched_max_numa_distance;
 static int			*sched_domains_numa_distance;
 static struct cpumask		***sched_domains_numa_masks;
-
-static unsigned long __read_mostly *sched_numa_onlined_nodes;
 #endif
 
 /*
@@ -1651,6 +1649,7 @@ static struct sched_domain_topology_level default_topology[] = {
 
 static struct sched_domain_topology_level *sched_domain_topology =
 	default_topology;
+static struct sched_domain_topology_level *sched_domain_topology_saved;
 
 #define for_each_sd_topology(tl)			\
 	for (tl = sched_domain_topology; tl->mask; tl++)
@@ -1661,6 +1660,7 @@ void set_sched_topology(struct sched_domain_topology_level *tl)
 		return;
 
 	sched_domain_topology = tl;
+	sched_domain_topology_saved = NULL;
 }
 
 #ifdef CONFIG_NUMA
@@ -1684,8 +1684,12 @@ static void sched_numa_warn(const char *str)
 
 	for (i = 0; i < nr_node_ids; i++) {
 		printk(KERN_WARNING "  ");
-		for (j = 0; j < nr_node_ids; j++)
-			printk(KERN_CONT "%02d ", node_distance(i,j));
+		for (j = 0; j < nr_node_ids; j++) {
+			if (!node_state(i, N_CPU) || !node_state(j, N_CPU))
+				printk(KERN_CONT "(%02d) ", node_distance(i,j));
+			else
+				printk(KERN_CONT " %02d  ", node_distance(i,j));
+		}
 		printk(KERN_CONT "\n");
 	}
 	printk(KERN_WARNING "\n");
@@ -1693,19 +1697,34 @@ static void sched_numa_warn(const char *str)
 
 bool find_numa_distance(int distance)
 {
-	int i;
+	bool found = false;
+	int i, *distances;
 
 	if (distance == node_distance(0, 0))
 		return true;
 
+	rcu_read_lock();
+	distances = rcu_dereference(sched_domains_numa_distance);
+	if (!distances)
+		goto unlock;
 	for (i = 0; i < sched_domains_numa_levels; i++) {
-		if (sched_domains_numa_distance[i] == distance)
-			return true;
+		if (distances[i] == distance) {
+			found = true;
+			break;
+		}
 	}
+unlock:
+	rcu_read_unlock();
 
-	return false;
+	return found;
 }
 
+#define for_each_cpu_node_but(n, nbut)		\
+	for_each_node_state(n, N_CPU)		\
+		if (n == nbut)			\
+			continue;		\
+		else
+
 /*
  * A system can have three types of NUMA topology:
  * NUMA_DIRECT: all nodes are directly connected, or not a NUMA system
@@ -1725,7 +1744,7 @@ bool find_numa_distance(int distance)
  *   there is an intermediary node C, which is < N hops away from both
  *   nodes A and B, the system is a glueless mesh.
  */
-static void init_numa_topology_type(void)
+static void init_numa_topology_type(int offline_node)
 {
 	int a, b, c, n;
 
@@ -1736,14 +1755,14 @@ static void init_numa_topology_type(void)
 		return;
 	}
 
-	for_each_online_node(a) {
-		for_each_online_node(b) {
+	for_each_cpu_node_but(a, offline_node) {
+		for_each_cpu_node_but(b, offline_node) {
 			/* Find two nodes furthest removed from each other. */
 			if (node_distance(a, b) < n)
 				continue;
 
 			/* Is there an intermediary node between a and b? */
-			for_each_online_node(c) {
+			for_each_cpu_node_but(c, offline_node) {
 				if (node_distance(a, c) < n &&
 				    node_distance(b, c) < n) {
 					sched_numa_topology_type =
@@ -1756,17 +1775,22 @@ static void init_numa_topology_type(void)
 			return;
 		}
 	}
+
+	pr_err("Failed to find a NUMA topology type, defaulting to DIRECT\n");
+	sched_numa_topology_type = NUMA_DIRECT;
 }
 
 
 #define NR_DISTANCE_VALUES (1 << DISTANCE_BITS)
 
-void sched_init_numa(void)
+void sched_init_numa(int offline_node)
 {
 	struct sched_domain_topology_level *tl;
 	unsigned long *distance_map;
 	int nr_levels = 0;
 	int i, j;
+	int *distances;
+	struct cpumask ***masks;
 
 	/*
 	 * O(nr_nodes^2) deduplicating selection sort -- in order to find the
@@ -1777,12 +1801,13 @@ void sched_init_numa(void)
 		return;
 
 	bitmap_zero(distance_map, NR_DISTANCE_VALUES);
-	for (i = 0; i < nr_node_ids; i++) {
-		for (j = 0; j < nr_node_ids; j++) {
+	for_each_cpu_node_but(i, offline_node) {
+		for_each_cpu_node_but(j, offline_node) {
 			int distance = node_distance(i, j);
 
 			if (distance < LOCAL_DISTANCE || distance >= NR_DISTANCE_VALUES) {
 				sched_numa_warn("Invalid distance value range");
+				bitmap_free(distance_map);
 				return;
 			}
 
@@ -1795,16 +1820,17 @@ void sched_init_numa(void)
 	 */
 	nr_levels = bitmap_weight(distance_map, NR_DISTANCE_VALUES);
 
-	sched_domains_numa_distance = kcalloc(nr_levels, sizeof(int), GFP_KERNEL);
-	if (!sched_domains_numa_distance) {
+	distances = kcalloc(nr_levels, sizeof(int), GFP_KERNEL);
+	if (!distances) {
 		bitmap_free(distance_map);
 		return;
 	}
 
 	for (i = 0, j = 0; i < nr_levels; i++, j++) {
 		j = find_next_bit(distance_map, NR_DISTANCE_VALUES, j);
-		sched_domains_numa_distance[i] = j;
+		distances[i] = j;
 	}
+	rcu_assign_pointer(sched_domains_numa_distance, distances);
 
 	bitmap_free(distance_map);
 
@@ -1826,8 +1852,8 @@ void sched_init_numa(void)
 	 */
 	sched_domains_numa_levels = 0;
 
-	sched_domains_numa_masks = kzalloc(sizeof(void *) * nr_levels, GFP_KERNEL);
-	if (!sched_domains_numa_masks)
+	masks = kzalloc(sizeof(void *) * nr_levels, GFP_KERNEL);
+	if (!masks)
 		return;
 
 	/*
@@ -1835,31 +1861,20 @@ void sched_init_numa(void)
 	 * CPUs of nodes that are that many hops away from us.
 	 */
 	for (i = 0; i < nr_levels; i++) {
-		sched_domains_numa_masks[i] =
-			kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
-		if (!sched_domains_numa_masks[i])
+		masks[i] = kzalloc(nr_node_ids * sizeof(void *), GFP_KERNEL);
+		if (!masks[i])
 			return;
 
-		for (j = 0; j < nr_node_ids; j++) {
+		for_each_cpu_node_but(j, offline_node) {
 			struct cpumask *mask = kzalloc(cpumask_size(), GFP_KERNEL);
 			int k;
 
 			if (!mask)
 				return;
 
-			sched_domains_numa_masks[i][j] = mask;
-
-			for_each_node(k) {
-				/*
-				 * Distance information can be unreliable for
-				 * offline nodes, defer building the node
-				 * masks to its bringup.
-				 * This relies on all unique distance values
-				 * still being visible at init time.
-				 */
-				if (!node_online(j))
-					continue;
+			masks[i][j] = mask;
 
+			for_each_cpu_node_but(k, offline_node) {
 				if (sched_debug() && (node_distance(j, k) != node_distance(k, j)))
 					sched_numa_warn("Node-distance not symmetric");
 
@@ -1870,6 +1885,7 @@ void sched_init_numa(void)
 			}
 		}
 	}
+	rcu_assign_pointer(sched_domains_numa_masks, masks);
 
 	/* Compute default topology size */
 	for (i = 0; sched_domain_topology[i].mask; i++);
@@ -1907,59 +1923,67 @@ void sched_init_numa(void)
 		};
 	}
 
+	sched_domain_topology_saved = sched_domain_topology;
 	sched_domain_topology = tl;
 
 	sched_domains_numa_levels = nr_levels;
-	sched_max_numa_distance = sched_domains_numa_distance[nr_levels - 1];
-
-	init_numa_topology_type();
-
-	sched_numa_onlined_nodes = bitmap_alloc(nr_node_ids, GFP_KERNEL);
-	if (!sched_numa_onlined_nodes)
-		return;
+	WRITE_ONCE(sched_max_numa_distance, sched_domains_numa_distance[nr_levels - 1]);
 
-	bitmap_zero(sched_numa_onlined_nodes, nr_node_ids);
-	for_each_online_node(i)
-		bitmap_set(sched_numa_onlined_nodes, i, 1);
+	init_numa_topology_type(offline_node);
 }
 
-static void __sched_domains_numa_masks_set(unsigned int node)
-{
-	int i, j;
-
-	/*
-	 * NUMA masks are not built for offline nodes in sched_init_numa().
-	 * Thus, when a CPU of a never-onlined-before node gets plugged in,
-	 * adding that new CPU to the right NUMA masks is not sufficient: the
-	 * masks of that CPU's node must also be updated.
-	 */
-	if (test_bit(node, sched_numa_onlined_nodes))
-		return;
 
-	bitmap_set(sched_numa_onlined_nodes, node, 1);
-
-	for (i = 0; i < sched_domains_numa_levels; i++) {
-		for (j = 0; j < nr_node_ids; j++) {
-			if (!node_online(j) || node == j)
-				continue;
+static void sched_reset_numa(void)
+{
+	int nr_levels, *distances;
+	struct cpumask ***masks;
 
-			if (node_distance(j, node) > sched_domains_numa_distance[i])
+	nr_levels = sched_domains_numa_levels;
+	sched_domains_numa_levels = 0;
+	sched_max_numa_distance = 0;
+	sched_numa_topology_type = NUMA_DIRECT;
+	distances = sched_domains_numa_distance;
+	rcu_assign_pointer(sched_domains_numa_distance, NULL);
+	masks = sched_domains_numa_masks;
+	rcu_assign_pointer(sched_domains_numa_masks, NULL);
+	if (distances || masks) {
+		int i, j;
+
+		synchronize_rcu();
+		kfree(distances);
+		for (i = 0; i < nr_levels && masks; i++) {
+			if (!masks[i])
 				continue;
-
-			/* Add remote nodes in our masks */
-			cpumask_or(sched_domains_numa_masks[i][node],
-				   sched_domains_numa_masks[i][node],
-				   sched_domains_numa_masks[0][j]);
+			for_each_node(j)
+				kfree(masks[i][j]);
+			kfree(masks[i]);
 		}
+		kfree(masks);
 	}
+	if (sched_domain_topology_saved) {
+		kfree(sched_domain_topology);
+		sched_domain_topology = sched_domain_topology_saved;
+		sched_domain_topology_saved = NULL;
+	}
+}
+
+/*
+ * Call with hotplug lock held
+ */
+void sched_update_numa(int cpu, bool online)
+{
+	int node;
 
+	node = cpu_to_node(cpu);
 	/*
-	 * A new node has been brought up, potentially changing the topology
-	 * classification.
-	 *
-	 * Note that this is racy vs any use of sched_numa_topology_type :/
+	 * Scheduler NUMA topology is updated when the first CPU of a
+	 * node is onlined or the last CPU of a node is offlined.
 	 */
-	init_numa_topology_type();
+	if (cpumask_weight(cpumask_of_node(node)) != 1)
+		return;
+
+	sched_reset_numa();
+	sched_init_numa(online ? NUMA_NO_NODE : node);
 }
 
 void sched_domains_numa_masks_set(unsigned int cpu)
@@ -1967,11 +1991,9 @@ void sched_domains_numa_masks_set(unsigned int cpu)
 	int node = cpu_to_node(cpu);
 	int i, j;
 
-	__sched_domains_numa_masks_set(node);
-
 	for (i = 0; i < sched_domains_numa_levels; i++) {
 		for (j = 0; j < nr_node_ids; j++) {
-			if (!node_online(j))
+			if (!node_state(j, N_CPU))
 				continue;
 
 			/* Set ourselves in the remote node's masks */
@@ -1986,8 +2008,10 @@ void sched_domains_numa_masks_clear(unsigned int cpu)
 	int i, j;
 
 	for (i = 0; i < sched_domains_numa_levels; i++) {
-		for (j = 0; j < nr_node_ids; j++)
-			cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
+		for (j = 0; j < nr_node_ids; j++) {
+			if (sched_domains_numa_masks[i][j])
+				cpumask_clear_cpu(cpu, sched_domains_numa_masks[i][j]);
+		}
 	}
 }
 
@@ -2001,14 +2025,26 @@ void sched_domains_numa_masks_clear(unsigned int cpu)
  */
 int sched_numa_find_closest(const struct cpumask *cpus, int cpu)
 {
-	int i, j = cpu_to_node(cpu);
+	int i, j = cpu_to_node(cpu), found = nr_cpu_ids;
+	struct cpumask ***masks;
 
+	rcu_read_lock();
+	masks = rcu_dereference(sched_domains_numa_masks);
+	if (!masks)
+		goto unlock;
 	for (i = 0; i < sched_domains_numa_levels; i++) {
-		cpu = cpumask_any_and(cpus, sched_domains_numa_masks[i][j]);
-		if (cpu < nr_cpu_ids)
-			return cpu;
+		if (!masks[i][j])
+			break;
+		cpu = cpumask_any_and(cpus, masks[i][j]);
+		if (cpu < nr_cpu_ids) {
+			found = cpu;
+			break;
+		}
 	}
-	return nr_cpu_ids;
+unlock:
+	rcu_read_unlock();
+
+	return found;
 }
 
 #endif /* CONFIG_NUMA */