[PATCH 1/1] sched: unthrottle rt runqueues in __disable_runtime()

[Peter Boonstoppel]

migrate_tasks() uses _pick_next_task_rt() to get tasks from the
real-time runqueues to be migrated. When rt_rq is throttled
_pick_next_task_rt() won't return anything, in which case
migrate_tasks() can't move all threads over and gets stuck in an
infinite loop.

Instead unthrottle rt runqueues before migrating tasks.

Additionally: move unthrottle_offline_cfs_rqs() to rq_offline_fair()

Signed-off-by: Peter Boonstoppel <pboonstop...@nvidia.com>
---
 kernel/sched/core.c  |    3 ---
 kernel/sched/fair.c  |    7 +++++--
 kernel/sched/rt.c    |    1 +
 kernel/sched/sched.h |    1 -
 4 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2df035a..2e7ecff 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5221,9 +5221,6 @@ static void migrate_tasks(unsigned int dead_cpu)
         */
        rq->stop = NULL;
 
-       /* Ensure any throttled groups are reachable by pick_next_task */
-       unthrottle_offline_cfs_rqs(rq);
-
        for ( ; ; ) {
                /*
                 * There's this thread running, bail when that's the only
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 3704ad3..dc8341b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2057,7 +2057,7 @@ static void destroy_cfs_bandwidth(struct cfs_bandwidth 
*cfs_b)
        hrtimer_cancel(&cfs_b->slack_timer);
 }
 
-void unthrottle_offline_cfs_rqs(struct rq *rq)
+static void unthrottle_offline_cfs_rqs(struct rq *rq)
 {
        struct cfs_rq *cfs_rq;
 
@@ -2111,7 +2111,7 @@ static inline struct cfs_bandwidth 
*tg_cfs_bandwidth(struct task_group *tg)
        return NULL;
 }
 static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
-void unthrottle_offline_cfs_rqs(struct rq *rq) {}
+static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
 
 #endif /* CONFIG_CFS_BANDWIDTH */
 
@@ -5086,6 +5086,9 @@ static void rq_online_fair(struct rq *rq)
 static void rq_offline_fair(struct rq *rq)
 {
        update_sysctl();
+
+       /* Ensure any throttled groups are reachable by pick_next_task */
+       unthrottle_offline_cfs_rqs(rq);
 }
 
 #endif /* CONFIG_SMP */
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 573e1ca..b9a94fb 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -691,6 +691,7 @@ balanced:
                 * runtime - in which case borrowing doesn't make sense.
                 */
                rt_rq->rt_runtime = RUNTIME_INF;
+               rt_rq->rt_throttled = 0;
                raw_spin_unlock(&rt_rq->rt_runtime_lock);
                raw_spin_unlock(&rt_b->rt_runtime_lock);
        }
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 4134d37..5d9aabe 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1167,7 +1167,6 @@ extern void print_rt_stats(struct seq_file *m, int cpu);
 
 extern void init_cfs_rq(struct cfs_rq *cfs_rq);
 extern void init_rt_rq(struct rt_rq *rt_rq, struct rq *rq);
-extern void unthrottle_offline_cfs_rqs(struct rq *rq);
 
 extern void account_cfs_bandwidth_used(int enabled, int was_enabled);
 
-- 
1.7.0.4--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/