cpuset: Fix cpuset_cpus_allowed_fallback(), don't update tsk->rt.nr_cpus_allowed

The rule is, we have to update tsk->rt.nr_cpus_allowed if we change
tsk->cpus_allowed. Otherwise RT scheduler may confuse.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4DD4B3FA.5060901@jp.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index f20eb8f..e9eaec5 100644 (file)
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -146,7 +146,7 @@ static inline void cpuset_cpus_allowed(struct task_struct *p,
 
 static inline int cpuset_cpus_allowed_fallback(struct task_struct *p)
 {
-       cpumask_copy(&p->cpus_allowed, cpu_possible_mask);
+       do_set_cpus_allowed(p, cpu_possible_mask);
        return cpumask_any(cpu_active_mask);
 }
 

diff --git a/include/linux/sched.h b/include/linux/sched.h
index dc88712..8da84b7 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1841,9 +1841,16 @@ static inline void rcu_copy_process(struct task_struct *p)
 #endif
 
 #ifdef CONFIG_SMP
+extern void do_set_cpus_allowed(struct task_struct *p,
+                              const struct cpumask *new_mask);
+
 extern int set_cpus_allowed_ptr(struct task_struct *p,
                                const struct cpumask *new_mask);
 #else
+static inline void do_set_cpus_allowed(struct task_struct *p,
+                                     const struct cpumask *new_mask)
+{
+}
 static inline int set_cpus_allowed_ptr(struct task_struct *p,
                                       const struct cpumask *new_mask)
 {

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 1ceeb04..9c9b754 100644 (file)
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2190,7 +2190,7 @@ int cpuset_cpus_allowed_fallback(struct task_struct *tsk)
        rcu_read_lock();
        cs = task_cs(tsk);
        if (cs)
-               cpumask_copy(&tsk->cpus_allowed, cs->cpus_allowed);
+               do_set_cpus_allowed(tsk, cs->cpus_allowed);
        rcu_read_unlock();
 
        /*
@@ -2217,7 +2217,7 @@ int cpuset_cpus_allowed_fallback(struct task_struct *tsk)
                 * Like above we can temporary set any mask and rely on
                 * set_cpus_allowed_ptr() as synchronization point.
                 */
-               cpumask_copy(&tsk->cpus_allowed, cpu_possible_mask);
+               do_set_cpus_allowed(tsk, cpu_possible_mask);
                cpu = cpumask_any(cpu_active_mask);
        }
 

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 3b34d27..4ba7ccc 100644 (file)
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -202,8 +202,8 @@ void kthread_bind(struct task_struct *p, unsigned int cpu)
                return;
        }
 
-       p->cpus_allowed = cpumask_of_cpu(cpu);
-       p->rt.nr_cpus_allowed = 1;
+       /* It's safe because the task is inactive. */
+       do_set_cpus_allowed(p, cpumask_of(cpu));
        p->flags |= PF_THREAD_BOUND;
 }
 EXPORT_SYMBOL(kthread_bind);

diff --git a/kernel/sched.c b/kernel/sched.c
index a80ee91..cbb3a0e 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5860,7 +5860,7 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu)
        idle->state = TASK_RUNNING;
        idle->se.exec_start = sched_clock();
 
-       cpumask_copy(&idle->cpus_allowed, cpumask_of(cpu));
+       do_set_cpus_allowed(idle, cpumask_of(cpu));
        /*
         * We're having a chicken and egg problem, even though we are
         * holding rq->lock, the cpu isn't yet set to this cpu so the
@@ -5948,6 +5948,16 @@ static inline void sched_init_granularity(void)
 }
 
 #ifdef CONFIG_SMP
+void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
+{
+       if (p->sched_class && p->sched_class->set_cpus_allowed)
+               p->sched_class->set_cpus_allowed(p, new_mask);
+       else {
+               cpumask_copy(&p->cpus_allowed, new_mask);
+               p->rt.nr_cpus_allowed = cpumask_weight(new_mask);
+       }
+}
+
 /*
  * This is how migration works:
  *
@@ -5993,12 +6003,7 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
                goto out;
        }
 
-       if (p->sched_class->set_cpus_allowed)
-               p->sched_class->set_cpus_allowed(p, new_mask);
-       else {
-               cpumask_copy(&p->cpus_allowed, new_mask);
-               p->rt.nr_cpus_allowed = cpumask_weight(new_mask);
-       }
+       do_set_cpus_allowed(p, new_mask);
 
        /* Can the task run on the task's current CPU? If so, we're done */
        if (cpumask_test_cpu(task_cpu(p), new_mask))