[PATCH] cpusets: fix the "dynamic sched domains" bug

For a NUMA system with multiple CPUs per node, declaring a cpu-exclusive
cpuset that includes only some, but not all, of the CPUs in a node will mangle
the sched domain structures.

Signed-off-by: John Hawkes <hawkes@sgi.com>
Cc; Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 69 insertions, 20 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 50860ad5b624..9508527845df 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4970,10 +4970,10 @@ static int cpu_to_phys_group(int cpu)
  * gets dynamically allocated.
  */
 static DEFINE_PER_CPU(struct sched_domain, node_domains);
-static struct sched_group *sched_group_nodes[MAX_NUMNODES];
+static struct sched_group **sched_group_nodes_bycpu[NR_CPUS];
 
 static DEFINE_PER_CPU(struct sched_domain, allnodes_domains);
-static struct sched_group sched_group_allnodes[MAX_NUMNODES];
+static struct sched_group *sched_group_allnodes_bycpu[NR_CPUS];
 
 static int cpu_to_allnodes_group(int cpu)
 {
@@ -4988,6 +4988,21 @@ static int cpu_to_allnodes_group(int cpu)
 void build_sched_domains(const cpumask_t *cpu_map)
 {
         int i;
+#ifdef CONFIG_NUMA
+        struct sched_group **sched_group_nodes = NULL;
+        struct sched_group *sched_group_allnodes = NULL;
+
+        /*
+         * Allocate the per-node list of sched groups
+         */
+        sched_group_nodes = kmalloc(sizeof(struct sched_group*)*MAX_NUMNODES,
+                                           GFP_ATOMIC);
+        if (!sched_group_nodes) {
+                printk(KERN_WARNING "Can not alloc sched group node list\n");
+                return;
+        }
+        sched_group_nodes_bycpu[first_cpu(*cpu_map)] = sched_group_nodes;
+#endif
 
         /*
          * Set up domains for cpus specified by the cpu_map.
@@ -5000,8 +5015,21 @@ void build_sched_domains(const cpumask_t *cpu_map)
                 cpus_and(nodemask, nodemask, *cpu_map);
 
 #ifdef CONFIG_NUMA
-                if (num_online_cpus()
+                if (cpus_weight(*cpu_map)
                                 > SD_NODES_PER_DOMAIN*cpus_weight(nodemask)) {
+                        if (!sched_group_allnodes) {
+                                sched_group_allnodes
+                                        = kmalloc(sizeof(struct sched_group)
+                                                        * MAX_NUMNODES,
+                                                  GFP_KERNEL);
+                                if (!sched_group_allnodes) {
+                                        printk(KERN_WARNING
+                                        "Can not alloc allnodes sched group\n");
+                                        break;
+                                }
+                                sched_group_allnodes_bycpu[i]
+                                                = sched_group_allnodes;
+                        }
                         sd = &per_cpu(allnodes_domains, i);
                         *sd = SD_ALLNODES_INIT;
                         sd->span = *cpu_map;
@@ -5065,8 +5093,9 @@ void build_sched_domains(const cpumask_t *cpu_map)
 
 #ifdef CONFIG_NUMA
         /* Set up node groups */
-        init_sched_build_groups(sched_group_allnodes, *cpu_map,
-                                &cpu_to_allnodes_group);
+        if (sched_group_allnodes)
+                init_sched_build_groups(sched_group_allnodes, *cpu_map,
+                                        &cpu_to_allnodes_group);
 
         for (i = 0; i < MAX_NUMNODES; i++) {
                 /* Set up node groups */
@@ -5077,8 +5106,10 @@ void build_sched_domains(const cpumask_t *cpu_map)
                 int j;
 
                 cpus_and(nodemask, nodemask, *cpu_map);
-                if (cpus_empty(nodemask))
+                if (cpus_empty(nodemask)) {
+                        sched_group_nodes[i] = NULL;
                         continue;
+                }
 
                 domainspan = sched_domain_node_span(i);
                 cpus_and(domainspan, domainspan, *cpu_map);
@@ -5223,24 +5254,42 @@ static void arch_destroy_sched_domains(const cpumask_t *cpu_map)
 {
 #ifdef CONFIG_NUMA
         int i;
-        for (i = 0; i < MAX_NUMNODES; i++) {
-                cpumask_t nodemask = node_to_cpumask(i);
-                struct sched_group *oldsg, *sg = sched_group_nodes[i];
+        int cpu;
 
-                cpus_and(nodemask, nodemask, *cpu_map);
-                if (cpus_empty(nodemask))
-                        continue;
+        for_each_cpu_mask(cpu, *cpu_map) {
+                struct sched_group *sched_group_allnodes
+                        = sched_group_allnodes_bycpu[cpu];
+                struct sched_group **sched_group_nodes
+                        = sched_group_nodes_bycpu[cpu];
 
-                if (sg == NULL)
+                if (sched_group_allnodes) {
+                        kfree(sched_group_allnodes);
+                        sched_group_allnodes_bycpu[cpu] = NULL;
+                }
+
+                if (!sched_group_nodes)
                         continue;
-                sg = sg->next;
+
+                for (i = 0; i < MAX_NUMNODES; i++) {
+                        cpumask_t nodemask = node_to_cpumask(i);
+                        struct sched_group *oldsg, *sg = sched_group_nodes[i];
+
+                        cpus_and(nodemask, nodemask, *cpu_map);
+                        if (cpus_empty(nodemask))
+                                continue;
+
+                        if (sg == NULL)
+                                continue;
+                        sg = sg->next;
 next_sg:
-                oldsg = sg;
-                sg = sg->next;
-                kfree(oldsg);
-                if (oldsg != sched_group_nodes[i])
-                        goto next_sg;
-                sched_group_nodes[i] = NULL;
+                        oldsg = sg;
+                        sg = sg->next;
+                        kfree(oldsg);
+                        if (oldsg != sched_group_nodes[i])
+                                goto next_sg;
+                }
+                kfree(sched_group_nodes);
+                sched_group_nodes_bycpu[cpu] = NULL;
         }
 #endif
 }