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

[sfrench/cifs-2.6.git] / kernel / sched / core.c

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f9a1346a5fa9502be6ca45ecb1bd822bf706725e..7880f4f64d0eea19dab03a0408625a505b4454ed 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1656,7 +1656,8 @@ static int __set_cpus_allowed_ptr(struct task_struct *p,
        if (cpumask_equal(p->cpus_ptr, new_mask))
                goto out;
 
-       if (!cpumask_intersects(new_mask, cpu_valid_mask)) {
+       dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask);
+       if (dest_cpu >= nr_cpu_ids) {
                ret = -EINVAL;
                goto out;
        }
@@ -1677,7 +1678,6 @@ static int __set_cpus_allowed_ptr(struct task_struct *p,
        if (cpumask_test_cpu(task_cpu(p), new_mask))
                goto out;
 
-       dest_cpu = cpumask_any_and(cpu_valid_mask, new_mask);
        if (task_running(rq, p) || p->state == TASK_WAKING) {
                struct migration_arg arg = { p, dest_cpu };
                /* Need help from migration thread: drop lock and wait. */
@@ -3254,7 +3254,7 @@ static struct rq *finish_task_switch(struct task_struct *prev)
                /* Task is done with its stack. */
                put_task_stack(prev);
 
-               put_task_struct(prev);
+               put_task_struct_rcu_user(prev);
        }
 
        tick_nohz_task_switch();
@@ -3358,15 +3358,15 @@ context_switch(struct rq *rq, struct task_struct *prev,
                else
                        prev->active_mm = NULL;
        } else {                                        // to user
+               membarrier_switch_mm(rq, prev->active_mm, next->mm);
                /*
                 * sys_membarrier() requires an smp_mb() between setting
-                * rq->curr and returning to userspace.
+                * rq->curr / membarrier_switch_mm() and returning to userspace.
                 *
                 * The below provides this either through switch_mm(), or in
                 * case 'prev->active_mm == next->mm' through
                 * finish_task_switch()'s mmdrop().
                 */
-
                switch_mm_irqs_off(prev->active_mm, next->mm, next);
 
                if (!prev->mm) {                        // from kernel
@@ -4042,7 +4042,11 @@ static void __sched notrace __schedule(bool preempt)
 
        if (likely(prev != next)) {
                rq->nr_switches++;
-               rq->curr = next;
+               /*
+                * RCU users of rcu_dereference(rq->curr) may not see
+                * changes to task_struct made by pick_next_task().
+                */
+               RCU_INIT_POINTER(rq->curr, next);
                /*
                 * The membarrier system call requires each architecture
                 * to have a full memory barrier after updating
@@ -4223,9 +4227,8 @@ static void __sched notrace preempt_schedule_common(void)
 
 #ifdef CONFIG_PREEMPTION
 /*
- * this is the entry point to schedule() from in-kernel preemption
- * off of preempt_enable. Kernel preemptions off return from interrupt
- * occur there and call schedule directly.
+ * This is the entry point to schedule() from in-kernel preemption
+ * off of preempt_enable.
  */
 asmlinkage __visible void __sched notrace preempt_schedule(void)
 {
@@ -4296,7 +4299,7 @@ EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
 #endif /* CONFIG_PREEMPTION */
 
 /*
- * this is the entry point to schedule() from kernel preemption
+ * This is the entry point to schedule() from kernel preemption
  * off of irq context.
  * Note, that this is called and return with irqs disabled. This will
  * protect us against recursive calling from irq.
@@ -6069,7 +6072,8 @@ void init_idle(struct task_struct *idle, int cpu)
        __set_task_cpu(idle, cpu);
        rcu_read_unlock();
 
-       rq->curr = rq->idle = idle;
+       rq->idle = idle;
+       rcu_assign_pointer(rq->curr, idle);
        idle->on_rq = TASK_ON_RQ_QUEUED;
 #ifdef CONFIG_SMP
        idle->on_cpu = 1;
@@ -6430,8 +6434,6 @@ int sched_cpu_activate(unsigned int cpu)
        }
        rq_unlock_irqrestore(rq, &rf);
 
-       update_max_interval();
-
        return 0;
 }