3.2.55-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Peter Boonstoppel <pboonstoppel@xxxxxxxxxx> commit a4c96ae319b8047f62dedbe1eac79e321c185749 upstream. 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 <pboonstoppel@xxxxxxxxxx> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Cc: Paul Turner <pjt@xxxxxxxxxx> Link: http://lkml.kernel.org/r/5FBF8E85CA34454794F0F7ECBA79798F379D3648B7@xxxxxxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> [ lizf: backported to 3.4: adjust context ] Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx> [bwh: Backported to 3.2: - Adjust filenames - unthrottle_offline_cfs_rqs() is already static, but defined in sched.c after including sched_fair.c, so add forward declaration - unthrottle_offline_cfs_rqs() also needs to be defined for all CONFIG_SMP configurations now] Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2189,6 +2189,10 @@ static int irqtime_account_si_update(voi #endif +#ifdef CONFIG_SMP +static void unthrottle_offline_cfs_rqs(struct rq *rq); +#endif + #include "sched_idletask.c" #include "sched_fair.c" #include "sched_rt.c" @@ -6566,8 +6570,6 @@ static void unthrottle_offline_cfs_rqs(s unthrottle_cfs_rq(cfs_rq); } } -#else -static void unthrottle_offline_cfs_rqs(struct rq *rq) {} #endif /* @@ -6595,9 +6597,6 @@ static void migrate_tasks(unsigned int d */ 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 @@ -6624,6 +6623,10 @@ static void migrate_tasks(unsigned int d #endif /* CONFIG_HOTPLUG_CPU */ +#if !defined(CONFIG_HOTPLUG_CPU) || !defined(CONFIG_CFS_BANDWIDTH) +static void unthrottle_offline_cfs_rqs(struct rq *rq) {} +#endif + #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL) static struct ctl_table sd_ctl_dir[] = { --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -4848,6 +4848,9 @@ 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); } #else /* CONFIG_SMP */ --- a/kernel/sched_rt.c +++ b/kernel/sched_rt.c @@ -509,6 +509,7 @@ 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); } -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html