[GIT PULL] scheduler fixes

Ingo Molnar
2011-05-28T16:40:46Z

Linus,

Please pull the latest sched-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git sched-urgent-for-linus

Thanks,

Ingo

------------------>
KOSAKI Motohiro (1):
cpuset: Fix cpuset_cpus_allowed_fallback(), don't update tsk->rt.nr_cpus_allowed

Peter Zijlstra (2):
sched: Fix ttwu() for __ARCH_WANT_INTERRUPTS_ON_CTXSW
sched: Fix ->min_vruntime calculation in dequeue_entity()

Xiaotian Feng (1):
sched: More sched_domain iterations fixes

include/linux/cpuset.h | 2 +-
include/linux/sched.h | 7 ++++++
kernel/cpuset.c | 4 +-
kernel/kthread.c | 4 +-
kernel/sched.c | 56 ++++++++++++++++++++++++++++++++++-------------
kernel/sched_fair.c | 5 ++-
kernel/sched_rt.c | 10 ++++++-
kernel/sched_stats.h | 4 +-
8 files changed, 65 insertions(+), 27 deletions(-)

diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index f20eb8f..e9eaec5 100644
--- 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
--- 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
--- 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
--- 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 5e43e9d..cbb3a0e 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2573,7 +2573,26 @@ static void ttwu_queue_remote(struct task_struct *p, int cpu)
if (!next)
smp_send_reschedule(cpu);
}
-#endif
+
+#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
+static int ttwu_activate_remote(struct task_struct *p, int wake_flags)
+{
+ struct rq *rq;
+ int ret = 0;
+
+ rq = __task_rq_lock(p);
+ if (p->on_cpu) {
+ ttwu_activate(rq, p, ENQUEUE_WAKEUP);
+ ttwu_do_wakeup(rq, p, wake_flags);
+ ret = 1;
+ }
+ __task_rq_unlock(rq);
+
+ return ret;
+
+}
+#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
+#endif /* CONFIG_SMP */

static void ttwu_queue(struct task_struct *p, int cpu)
{
@@ -2631,17 +2650,17 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
while (p->on_cpu) {
#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
/*
- * If called from interrupt context we could have landed in the
- * middle of schedule(), in this case we should take care not
- * to spin on ->on_cpu if p is current, since that would
- * deadlock.
+ * In case the architecture enables interrupts in
+ * context_switch(), we cannot busy wait, since that
+ * would lead to deadlocks when an interrupt hits and
+ * tries to wake up @prev. So bail and do a complete
+ * remote wakeup.
*/
- if (p == current) {
- ttwu_queue(p, cpu);
+ if (ttwu_activate_remote(p, wake_flags))
goto stat;
- }
-#endif
+#else
cpu_relax();
+#endif
}
/*
* Pairs with the smp_wmb() in finish_lock_switch().
@@ -5841,7 +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
@@ -5929,6 +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:
*
@@ -5974,12 +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))
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index e32a9b7..433491c 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1076,8 +1076,6 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
se->on_rq = 0;
update_cfs_load(cfs_rq, 0);
account_entity_dequeue(cfs_rq, se);
- update_min_vruntime(cfs_rq);
- update_cfs_shares(cfs_rq);

/*
* Normalize the entity after updating the min_vruntime because the
@@ -1086,6 +1084,9 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
*/
if (!(flags & DEQUEUE_SLEEP))
se->vruntime -= cfs_rq->min_vruntime;
+
+ update_min_vruntime(cfs_rq);
+ update_cfs_shares(cfs_rq);
}

/*
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 64b2a37..88725c9 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1263,6 +1263,7 @@ static int find_lowest_rq(struct task_struct *task)
if (!cpumask_test_cpu(this_cpu, lowest_mask))
this_cpu = -1; /* Skip this_cpu opt if not among lowest */

+ rcu_read_lock();
for_each_domain(cpu, sd) {
if (sd->flags & SD_WAKE_AFFINE) {
int best_cpu;
@@ -1272,15 +1273,20 @@ static int find_lowest_rq(struct task_struct *task)
* remote processor.
*/
if (this_cpu != -1 &&
- cpumask_test_cpu(this_cpu, sched_domain_span(sd)))
+ cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
+ rcu_read_unlock();
return this_cpu;
+ }

best_cpu = cpumask_first_and(lowest_mask,
sched_domain_span(sd));
- if (best_cpu < nr_cpu_ids)
+ if (best_cpu < nr_cpu_ids) {
+ rcu_read_unlock();
return best_cpu;
+ }
}
}
+ rcu_read_unlock();

/*
* And finally, if there were no matches within the domains
diff --git a/kernel/sched_stats.h b/kernel/sched_stats.h
index 48ddf43..331e01b 100644
--- a/kernel/sched_stats.h
+++ b/kernel/sched_stats.h
@@ -37,7 +37,7 @@ static int show_schedstat(struct seq_file *seq, void *v)

#ifdef CONFIG_SMP
/* domain-specific stats */
- preempt_disable();
+ rcu_read_lock();
for_each_domain(cpu, sd) {
enum cpu_idle_type itype;

@@ -64,7 +64,7 @@ static int show_schedstat(struct seq_file *seq, void *v)
sd->ttwu_wake_remote, sd->ttwu_move_affine,
sd->ttwu_move_balance);
}
- preempt_enable();
+ rcu_read_unlock();
#endif
}
kfree(mask_str);