Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fixes from Ingo Molnar:
 "A CPU hotplug related crash fix and a nohz accounting fixlet."

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Update sched_domains_numa_masks[][] when new cpus are onlined
  sched: Ensure 'sched_domains_numa_levels' is safe to use in other functions
  nohz: Fix one jiffy count too far in idle cputime

1 files changed, 69 insertions, 0 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index bd7c39450b1b..2d8927fda712 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6122,6 +6122,17 @@ static void sched_init_numa(void)
          * numbers.
          */
 
+        /*
+         * Here, we should temporarily reset sched_domains_numa_levels to 0.
+         * If it fails to allocate memory for array sched_domains_numa_masks[][],
+         * the array will contain less then 'level' members. This could be
+         * dangerous when we use it to iterate array sched_domains_numa_masks[][]
+         * in other functions.
+         *
+         * We reset it to 'level' at the end of this function.
+         */
+        sched_domains_numa_levels = 0;
+
         sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
         if (!sched_domains_numa_masks)
                 return;
@@ -6176,11 +6187,68 @@ static void sched_init_numa(void)
         }
 
         sched_domain_topology = tl;
+
+        sched_domains_numa_levels = level;
+}
+
+static void sched_domains_numa_masks_set(int cpu)
+{
+        int i, j;
+        int node = cpu_to_node(cpu);
+
+        for (i = 0; i < sched_domains_numa_levels; i++) {
+                for (j = 0; j < nr_node_ids; j++) {
+                        if (node_distance(j, node) <= sched_domains_numa_distance[i])
+                                cpumask_set_cpu(cpu, sched_domains_numa_masks[i][j]);
+                }
+        }
+}
+
+static void sched_domains_numa_masks_clear(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]);
+        }
+}
+
+/*
+ * Update sched_domains_numa_masks[level][node] array when new cpus
+ * are onlined.
+ */
+static int sched_domains_numa_masks_update(struct notifier_block *nfb,
+                                           unsigned long action,
+                                           void *hcpu)
+{
+        int cpu = (long)hcpu;
+
+        switch (action & ~CPU_TASKS_FROZEN) {
+        case CPU_ONLINE:
+                sched_domains_numa_masks_set(cpu);
+                break;
+
+        case CPU_DEAD:
+                sched_domains_numa_masks_clear(cpu);
+                break;
+
+        default:
+                return NOTIFY_DONE;
+        }
+
+        return NOTIFY_OK;
 }
 #else
 static inline void sched_init_numa(void)
 {
 }
+
+static int sched_domains_numa_masks_update(struct notifier_block *nfb,
+                                           unsigned long action,
+                                           void *hcpu)
+{
+        return 0;
+}
 #endif /* CONFIG_NUMA */
 
 static int __sdt_alloc(const struct cpumask *cpu_map)
@@ -6629,6 +6697,7 @@ void __init sched_init_smp(void)
         mutex_unlock(&sched_domains_mutex);
         put_online_cpus();
 
+        hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);
         hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);
         hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);