forked from luck/tmp_suning_uos_patched
sched: Fix select_task_rq() vs hotplug issues
Since select_task_rq() is now responsible for guaranteeing ->cpus_allowed and cpu_active_mask, we need to verify this. select_task_rq_rt() can blindly return smp_processor_id()/task_cpu() without checking the valid masks, select_task_rq_fair() can do the same in the rare case that all SD_flags are disabled. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> LKML-Reference: <20091216170517.961475466@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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3802290628
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@ -2317,6 +2317,43 @@ void task_oncpu_function_call(struct task_struct *p,
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}
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#ifdef CONFIG_SMP
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static int select_fallback_rq(int cpu, struct task_struct *p)
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{
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int dest_cpu;
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const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(cpu));
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/* Look for allowed, online CPU in same node. */
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for_each_cpu_and(dest_cpu, nodemask, cpu_active_mask)
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if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
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return dest_cpu;
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/* Any allowed, online CPU? */
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dest_cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask);
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if (dest_cpu < nr_cpu_ids)
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return dest_cpu;
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/* No more Mr. Nice Guy. */
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if (dest_cpu >= nr_cpu_ids) {
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rcu_read_lock();
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cpuset_cpus_allowed_locked(p, &p->cpus_allowed);
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rcu_read_unlock();
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dest_cpu = cpumask_any_and(cpu_active_mask, &p->cpus_allowed);
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/*
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* Don't tell them about moving exiting tasks or
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* kernel threads (both mm NULL), since they never
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* leave kernel.
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*/
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if (p->mm && printk_ratelimit()) {
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printk(KERN_INFO "process %d (%s) no "
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"longer affine to cpu%d\n",
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task_pid_nr(p), p->comm, cpu);
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}
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}
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return dest_cpu;
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}
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/*
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* Called from:
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*
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@ -2343,14 +2380,8 @@ int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags)
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* not worry about this generic constraint ]
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*/
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if (unlikely(!cpumask_test_cpu(cpu, &p->cpus_allowed) ||
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!cpu_active(cpu))) {
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cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask);
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/*
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* XXX: race against hot-plug modifying cpu_active_mask
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*/
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BUG_ON(cpu >= nr_cpu_ids);
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}
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!cpu_active(cpu)))
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cpu = select_fallback_rq(task_cpu(p), p);
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return cpu;
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}
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@ -7319,36 +7350,10 @@ static int __migrate_task_irq(struct task_struct *p, int src_cpu, int dest_cpu)
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static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
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{
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int dest_cpu;
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const struct cpumask *nodemask = cpumask_of_node(cpu_to_node(dead_cpu));
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again:
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/* Look for allowed, online CPU in same node. */
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for_each_cpu_and(dest_cpu, nodemask, cpu_active_mask)
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if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed))
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goto move;
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dest_cpu = select_fallback_rq(dead_cpu, p);
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/* Any allowed, online CPU? */
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dest_cpu = cpumask_any_and(&p->cpus_allowed, cpu_active_mask);
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if (dest_cpu < nr_cpu_ids)
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goto move;
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/* No more Mr. Nice Guy. */
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if (dest_cpu >= nr_cpu_ids) {
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cpuset_cpus_allowed_locked(p, &p->cpus_allowed);
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dest_cpu = cpumask_any_and(cpu_active_mask, &p->cpus_allowed);
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/*
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* Don't tell them about moving exiting tasks or
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* kernel threads (both mm NULL), since they never
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* leave kernel.
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*/
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if (p->mm && printk_ratelimit()) {
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pr_info("process %d (%s) no longer affine to cpu%d\n",
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task_pid_nr(p), p->comm, dead_cpu);
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}
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}
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move:
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/* It can have affinity changed while we were choosing. */
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if (unlikely(!__migrate_task_irq(p, dead_cpu, dest_cpu)))
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goto again;
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