Merge branch 'for-3.14-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj...

[~andy/linux] / kernel / cpu.c

diff --git a/kernel/cpu.c b/kernel/cpu.c
index d7f07a2da5a6b6bcc682d39918b3bd97471d9543..deff2e693766997a259b4b3ac2fc4f789e554f1d 100644 (file)
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -306,8 +306,28 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
                                __func__, cpu);
                goto out_release;
        }
+
+       /*
+        * By now we've cleared cpu_active_mask, wait for all preempt-disabled
+        * and RCU users of this state to go away such that all new such users
+        * will observe it.
+        *
+        * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might
+        * not imply sync_sched(), so explicitly call both.
+        *
+        * Do sync before park smpboot threads to take care the rcu boost case.
+        */
+#ifdef CONFIG_PREEMPT
+       synchronize_sched();
+#endif
+       synchronize_rcu();
+
        smpboot_park_threads(cpu);
 
+       /*
+        * So now all preempt/rcu users must observe !cpu_active().
+        */
+
        err = __stop_machine(take_cpu_down, &tcd_param, cpumask_of(cpu));
        if (err) {
                /* CPU didn't die: tell everyone.  Can't complain. */
@@ -420,11 +440,6 @@ int cpu_up(unsigned int cpu)
 {
        int err = 0;
 
-#ifdef CONFIG_MEMORY_HOTPLUG
-       int nid;
-       pg_data_t       *pgdat;
-#endif
-
        if (!cpu_possible(cpu)) {
                printk(KERN_ERR "can't online cpu %d because it is not "
                        "configured as may-hotadd at boot time\n", cpu);
@@ -435,27 +450,9 @@ int cpu_up(unsigned int cpu)
                return -EINVAL;
        }
 
-#ifdef CONFIG_MEMORY_HOTPLUG
-       nid = cpu_to_node(cpu);
-       if (!node_online(nid)) {
-               err = mem_online_node(nid);
-               if (err)
-                       return err;
-       }
-
-       pgdat = NODE_DATA(nid);
-       if (!pgdat) {
-               printk(KERN_ERR
-                       "Can't online cpu %d due to NULL pgdat\n", cpu);
-               return -ENOMEM;
-       }
-
-       if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
-               mutex_lock(&zonelists_mutex);
-               build_all_zonelists(NULL, NULL);
-               mutex_unlock(&zonelists_mutex);
-       }
-#endif
+       err = try_online_node(cpu_to_node(cpu));
+       if (err)
+               return err;
 
        cpu_maps_update_begin();