Re: [ANNOUNCE] v4.14.29-rt25

From: Grygorii Strashko
Date: Tue May 01 2018 - 11:04:34 EST

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Hi Sebastian,

On 04/23/2018 02:10 PM, Sebastian Andrzej Siewior wrote:
> On 2018-04-23 11:57:39 [-0500], Grygorii Strashko wrote:
>> Sry, but I can't apply it. What's you base?
>
> please try this patch and latest v4.14-RT

I've tried this (with v4.14.34-rt27) and I do not see rcu_note_context_switch() any more.

Sry, it took some time as i found some instability -
test "stress-ng --class os --all 0 -t 5m " not always finished :(
So, I've tried to rollback to v4.14.29-rt25 and use as TI RT kernel as
pure rt-devel. Still not sure if this is some sort of regression or not.

>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index e305a8f8cd7d..0322503084a5 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -600,6 +600,9 @@ struct task_struct {
> int migrate_disable_atomic;
> # endif
> #endif
> +#ifdef CONFIG_PREEMPT_RT_FULL
> + int sleeping_lock;
> +#endif
>
> #ifdef CONFIG_PREEMPT_RCU
> int rcu_read_lock_nesting;
> @@ -1757,6 +1760,23 @@ static __always_inline bool need_resched(void)
> return unlikely(tif_need_resched());
> }
>
> +#ifdef CONFIG_PREEMPT_RT_FULL
> +static inline void sleeping_lock_inc(void)
> +{
> + current->sleeping_lock++;
> +}
> +
> +static inline void sleeping_lock_dec(void)
> +{
> + current->sleeping_lock--;
> +}
> +
> +#else
> +
> +static inline void sleeping_lock_inc(void) { }
> +static inline void sleeping_lock_dec(void) { }
> +#endif
> +
> /*
> * Wrappers for p->thread_info->cpu access. No-op on UP.
> */
> diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
> index 0cb716ba3be0..bac3fb580af6 100644
> --- a/kernel/locking/rtmutex.c
> +++ b/kernel/locking/rtmutex.c
> @@ -1141,6 +1141,7 @@ void __sched rt_spin_lock_slowunlock(struct rt_mutex *lock)
>
> void __lockfunc rt_spin_lock(spinlock_t *lock)
> {
> + sleeping_lock_inc();
> migrate_disable();
> spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
> rt_spin_lock_fastlock(&lock->lock, rt_spin_lock_slowlock);
> @@ -1155,6 +1156,7 @@ void __lockfunc __rt_spin_lock(struct rt_mutex *lock)
> #ifdef CONFIG_DEBUG_LOCK_ALLOC
> void __lockfunc rt_spin_lock_nested(spinlock_t *lock, int subclass)
> {
> + sleeping_lock_inc();
> migrate_disable();
> spin_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
> rt_spin_lock_fastlock(&lock->lock, rt_spin_lock_slowlock);
> @@ -1168,6 +1170,7 @@ void __lockfunc rt_spin_unlock(spinlock_t *lock)
> spin_release(&lock->dep_map, 1, _RET_IP_);
> rt_spin_lock_fastunlock(&lock->lock, rt_spin_lock_slowunlock);
> migrate_enable();
> + sleeping_lock_dec();
> }
> EXPORT_SYMBOL(rt_spin_unlock);
>
> @@ -1193,12 +1196,15 @@ int __lockfunc rt_spin_trylock(spinlock_t *lock)
> {
> int ret;
>
> + sleeping_lock_inc();
> migrate_disable();
> ret = __rt_mutex_trylock(&lock->lock);
> - if (ret)
> + if (ret) {
> spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
> - else
> + } else {
> migrate_enable();
> + sleeping_lock_dec();
> + }
> return ret;
> }
> EXPORT_SYMBOL(rt_spin_trylock);
> @@ -1210,6 +1216,7 @@ int __lockfunc rt_spin_trylock_bh(spinlock_t *lock)
> local_bh_disable();
> ret = __rt_mutex_trylock(&lock->lock);
> if (ret) {
> + sleeping_lock_inc();
> migrate_disable();
> spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
> } else
> @@ -1225,6 +1232,7 @@ int __lockfunc rt_spin_trylock_irqsave(spinlock_t *lock, unsigned long *flags)
> *flags = 0;
> ret = __rt_mutex_trylock(&lock->lock);
> if (ret) {
> + sleeping_lock_inc();
> migrate_disable();
> spin_acquire(&lock->dep_map, 0, 1, _RET_IP_);
> }
> diff --git a/kernel/locking/rwlock-rt.c b/kernel/locking/rwlock-rt.c
> index aebb7ce25bc6..f2e155b2c4a8 100644
> --- a/kernel/locking/rwlock-rt.c
> +++ b/kernel/locking/rwlock-rt.c
> @@ -305,12 +305,15 @@ int __lockfunc rt_read_trylock(rwlock_t *rwlock)
> {
> int ret;
>
> + sleeping_lock_inc();
> migrate_disable();
> ret = do_read_rt_trylock(rwlock);
> - if (ret)
> + if (ret) {
> rwlock_acquire_read(&rwlock->dep_map, 0, 1, _RET_IP_);
> - else
> + } else {
> migrate_enable();
> + sleeping_lock_dec();
> + }
> return ret;
> }
> EXPORT_SYMBOL(rt_read_trylock);
> @@ -319,18 +322,22 @@ int __lockfunc rt_write_trylock(rwlock_t *rwlock)
> {
> int ret;
>
> + sleeping_lock_inc();
> migrate_disable();
> ret = do_write_rt_trylock(rwlock);
> - if (ret)
> + if (ret) {
> rwlock_acquire(&rwlock->dep_map, 0, 1, _RET_IP_);
> - else
> + } else {
> migrate_enable();
> + sleeping_lock_dec();
> + }
> return ret;
> }
> EXPORT_SYMBOL(rt_write_trylock);
>
> void __lockfunc rt_read_lock(rwlock_t *rwlock)
> {
> + sleeping_lock_inc();
> migrate_disable();
> rwlock_acquire_read(&rwlock->dep_map, 0, 0, _RET_IP_);
> do_read_rt_lock(rwlock);
> @@ -339,6 +346,7 @@ EXPORT_SYMBOL(rt_read_lock);
>
> void __lockfunc rt_write_lock(rwlock_t *rwlock)
> {
> + sleeping_lock_inc();
> migrate_disable();
> rwlock_acquire(&rwlock->dep_map, 0, 0, _RET_IP_);
> do_write_rt_lock(rwlock);
> @@ -350,6 +358,7 @@ void __lockfunc rt_read_unlock(rwlock_t *rwlock)
> rwlock_release(&rwlock->dep_map, 1, _RET_IP_);
> do_read_rt_unlock(rwlock);
> migrate_enable();
> + sleeping_lock_dec();
> }
> EXPORT_SYMBOL(rt_read_unlock);
>
> @@ -358,6 +367,7 @@ void __lockfunc rt_write_unlock(rwlock_t *rwlock)
> rwlock_release(&rwlock->dep_map, 1, _RET_IP_);
> do_write_rt_unlock(rwlock);
> migrate_enable();
> + sleeping_lock_dec();
> }
> EXPORT_SYMBOL(rt_write_unlock);
>
> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> index 3315ebad932f..c6098f60e641 100644
> --- a/kernel/rcu/tree_plugin.h
> +++ b/kernel/rcu/tree_plugin.h
> @@ -301,13 +301,13 @@ static void rcu_preempt_note_context_switch(bool preempt)
> struct task_struct *t = current;
> struct rcu_data *rdp;
> struct rcu_node *rnp;
> - int mg_counter = 0;
> + int sleeping_l = 0;
>
> RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_preempt_note_context_switch() invoked with interrupts enabled!!!\n");
> -#if defined(CONFIG_PREEMPT_RT_BASE)
> - mg_counter = t->migrate_disable;
> +#if defined(CONFIG_PREEMPT_RT_FULL)
> + sleeping_l = t->sleeping_lock;
> #endif
> - WARN_ON_ONCE(!preempt && t->rcu_read_lock_nesting > 0 && !mg_counter);
> + WARN_ON_ONCE(!preempt && t->rcu_read_lock_nesting > 0 && !sleeping_l);
> if (t->rcu_read_lock_nesting > 0 &&
> !t->rcu_read_unlock_special.b.blocked) {
>
> diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
> index ce2c2d04cbaa..b59e009087a9 100644
> --- a/kernel/time/hrtimer.c
> +++ b/kernel/time/hrtimer.c
> @@ -1870,7 +1870,9 @@ void cpu_chill(void)
> chill_time = ktime_set(0, NSEC_PER_MSEC);
> set_current_state(TASK_UNINTERRUPTIBLE);
> current->flags |= PF_NOFREEZE;
> + sleeping_lock_inc();
> schedule_hrtimeout(&chill_time, HRTIMER_MODE_REL_HARD);
> + sleeping_lock_dec();
> if (!freeze_flag)
> current->flags &= ~PF_NOFREEZE;
> }
>
> Sebastian
>

--
regards,
-grygorii

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