4 files changed, 36 insertions, 6 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 1a649f2bb9bb..4ea6f0dc2fc5 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -816,6 +816,10 @@ static int update_cpumask(struct cpuset *cs, char *buf)
         struct cpuset trialcs;
         int retval, cpus_unchanged;
 
+        /* top_cpuset.cpus_allowed tracks cpu_online_map; it's read-only */
+        if (cs == &top_cpuset)
+                return -EACCES;
+
         trialcs = *cs;
         retval = cpulist_parse(buf, trialcs.cpus_allowed);
         if (retval < 0)
@@ -2033,6 +2037,33 @@ out:
         return err;
 }
 
+/*
+ * The top_cpuset tracks what CPUs and Memory Nodes are online,
+ * period.  This is necessary in order to make cpusets transparent
+ * (of no affect) on systems that are actively using CPU hotplug
+ * but making no active use of cpusets.
+ *
+ * This handles CPU hotplug (cpuhp) events.  If someday Memory
+ * Nodes can be hotplugged (dynamically changing node_online_map)
+ * then we should handle that too, perhaps in a similar way.
+ */
+
+#ifdef CONFIG_HOTPLUG_CPU
+static int cpuset_handle_cpuhp(struct notifier_block *nb,
+                                unsigned long phase, void *cpu)
+{
+        mutex_lock(&manage_mutex);
+        mutex_lock(&callback_mutex);
+
+        top_cpuset.cpus_allowed = cpu_online_map;
+
+        mutex_unlock(&callback_mutex);
+        mutex_unlock(&manage_mutex);
+
+        return 0;
+}
+#endif
+
 /**
  * cpuset_init_smp - initialize cpus_allowed
  *
@@ -2043,6 +2074,8 @@ void __init cpuset_init_smp(void)
 {
         top_cpuset.cpus_allowed = cpu_online_map;
         top_cpuset.mems_allowed = node_online_map;
+
+        hotcpu_notifier(cpuset_handle_cpuhp, 0);
 }
 
 /**
@@ -2387,7 +2420,7 @@ EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
 int cpuset_excl_nodes_overlap(const struct task_struct *p)
 {
         const struct cpuset *cs1, *cs2; /* my and p's cpuset ancestors */
-        int overlap = 0;                /* do cpusets overlap? */
+        int overlap = 1;                /* do cpusets overlap? */
 
         task_lock(current);
         if (current->flags & PF_EXITING) {
diff --git a/kernel/futex.c b/kernel/futex.c
index d4633c588f33..b9b8aea5389e 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -397,7 +397,7 @@ static struct task_struct * futex_find_get_task(pid_t pid)
                 p = NULL;
                 goto out_unlock;
         }
-        if (p->state == EXIT_ZOMBIE || p->exit_state == EXIT_ZOMBIE) {
+        if (p->exit_state != 0) {
                 p = NULL;
                 goto out_unlock;
         }
diff --git a/kernel/sched.c b/kernel/sched.c
index a2be2d055299..a234fbee1238 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4162,10 +4162,8 @@ do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param)
                 read_unlock_irq(&tasklist_lock);
                 return -ESRCH;
         }
-        get_task_struct(p);
-        read_unlock_irq(&tasklist_lock);
         retval = sched_setscheduler(p, policy, &lparam);
-        put_task_struct(p);
+        read_unlock_irq(&tasklist_lock);
 
         return retval;
 }
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index dcfb5d731466..51cacd111dbd 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -111,7 +111,6 @@ static int stop_machine(void)
         /* If some failed, kill them all. */
         if (ret < 0) {
                 stopmachine_set_state(STOPMACHINE_EXIT);
-                up(&stopmachine_mutex);
                 return ret;
         }