[GIT PULL] scheduler fixes

Ingo Molnar
2014-04-19T10:55:58Z

Linus,

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

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

# HEAD: a1d9a3231eac4117cadaf4b6bba5b2902c15a33e sched: Check for stop task appearance when balancing happens

Two fixes:

- a SCHED_DEADLINE task selection fix
- a sched/numa related lockdep splat fix

Thanks,

Ingo

------------------>
Kirill Tkhai (1):
sched: Check for stop task appearance when balancing happens

Mike Galbraith (1):
sched/numa: Fix task_numa_free() lockdep splat

kernel/sched/deadline.c | 11 ++++++++++-
kernel/sched/fair.c | 16 +++++++++-------
kernel/sched/rt.c | 7 ++++---
kernel/sched/sched.h | 9 +++++++++
4 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 27ef409..b080957 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1021,8 +1021,17 @@ struct task_struct *pick_next_task_dl(struct rq *rq, struct task_struct *prev)

dl_rq = &rq->dl;

- if (need_pull_dl_task(rq, prev))
+ if (need_pull_dl_task(rq, prev)) {
pull_dl_task(rq);
+ /*
+ * pull_rt_task() can drop (and re-acquire) rq->lock; this
+ * means a stop task can slip in, in which case we need to
+ * re-start task selection.
+ */
+ if (rq->stop && rq->stop->on_rq)
+ return RETRY_TASK;
+ }
+
/*
* When prev is DL, we may throttle it in put_prev_task().
* So, we update time before we check for dl_nr_running.
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7e9bd0b..7570dd9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1497,7 +1497,7 @@ static void task_numa_placement(struct task_struct *p)
/* If the task is part of a group prevent parallel updates to group stats */
if (p->numa_group) {
group_lock = &p->numa_group->lock;
- spin_lock(group_lock);
+ spin_lock_irq(group_lock);
}

/* Find the node with the highest number of faults */
@@ -1572,7 +1572,7 @@ static void task_numa_placement(struct task_struct *p)
}
}

- spin_unlock(group_lock);
+ spin_unlock_irq(group_lock);
}

/* Preferred node as the node with the most faults */
@@ -1677,7 +1677,8 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
if (!join)
return;

- double_lock(&my_grp->lock, &grp->lock);
+ BUG_ON(irqs_disabled());
+ double_lock_irq(&my_grp->lock, &grp->lock);

for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) {
my_grp->faults[i] -= p->numa_faults_memory[i];
@@ -1691,7 +1692,7 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
grp->nr_tasks++;

spin_unlock(&my_grp->lock);
- spin_unlock(&grp->lock);
+ spin_unlock_irq(&grp->lock);

rcu_assign_pointer(p->numa_group, grp);

@@ -1710,14 +1711,14 @@ void task_numa_free(struct task_struct *p)
void *numa_faults = p->numa_faults_memory;

if (grp) {
- spin_lock(&grp->lock);
+ spin_lock_irq(&grp->lock);
for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++)
grp->faults[i] -= p->numa_faults_memory[i];
grp->total_faults -= p->total_numa_faults;

list_del(&p->numa_entry);
grp->nr_tasks--;
- spin_unlock(&grp->lock);
+ spin_unlock_irq(&grp->lock);
rcu_assign_pointer(p->numa_group, NULL);
put_numa_group(grp);
}
@@ -6727,7 +6728,8 @@ static int idle_balance(struct rq *this_rq)
out:
/* Is there a task of a high priority class? */
if (this_rq->nr_running != this_rq->cfs.h_nr_running &&
- (this_rq->dl.dl_nr_running ||
+ ((this_rq->stop && this_rq->stop->on_rq) ||
+ this_rq->dl.dl_nr_running ||
(this_rq->rt.rt_nr_running && !rt_rq_throttled(&this_rq->rt))))
pulled_task = -1;

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index d8cdf16..bd2267a 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1362,10 +1362,11 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev)
pull_rt_task(rq);
/*
* pull_rt_task() can drop (and re-acquire) rq->lock; this
- * means a dl task can slip in, in which case we need to
- * re-start task selection.
+ * means a dl or stop task can slip in, in which case we need
+ * to re-start task selection.
*/
- if (unlikely(rq->dl.dl_nr_running))
+ if (unlikely((rq->stop && rq->stop->on_rq) ||
+ rq->dl.dl_nr_running))
return RETRY_TASK;
}

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c9007f2..456e492 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1385,6 +1385,15 @@ static inline void double_lock(spinlock_t *l1, spinlock_t *l2)
spin_lock_nested(l2, SINGLE_DEPTH_NESTING);
}

+static inline void double_lock_irq(spinlock_t *l1, spinlock_t *l2)
+{
+ if (l1 > l2)
+ swap(l1, l2);
+
+ spin_lock_irq(l1);
+ spin_lock_nested(l2, SINGLE_DEPTH_NESTING);
+}
+
static inline void double_raw_lock(raw_spinlock_t *l1, raw_spinlock_t *l2)
{
if (l1 > l2)