On Mon, 2019-02-25 at 17:34 +0100, Sebastian Andrzej Siewior wrote:
> On 2019-02-25 15:43:35 [+0100], Mike Galbraith wrote:
> > Hi Sebastian,
> Hi Mike,
>
> > My box claims that this patch is busted. It argues its case by IO
> > deadlocking any kernel this patch is applied to when spinning rust is
> > flogged, including virgin 4.19-rt14, said kernel becoming stable again
> > when I whack the accused.
>
> does the following hunk make any difference?
Ah. Yup, box says you're right.
> diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
> index 6ecdb9469ca9..e154632b90b4 100644
> --- a/kernel/time/hrtimer.c
> +++ b/kernel/time/hrtimer.c
> @@ -1884,20 +1884,29 @@ COMPAT_SYSCALL_DEFINE2(nanosleep, struct old_timespec32 __user *, rqtp,
> */
> void cpu_chill(void)
> {
> + struct task_struct *self = current;
> ktime_t chill_time;
> unsigned int freeze_flag = current->flags & PF_NOFREEZE;
> - long saved_state;
>
> - saved_state = current->state;
> - chill_time = ktime_set(0, NSEC_PER_MSEC);
> + raw_spin_lock_irq(&self->pi_lock);
> + WARN_ON(self->saved_state != TASK_RUNNING);
> + self->saved_state = self->state;
> __set_current_state_no_track(TASK_UNINTERRUPTIBLE);
> + raw_spin_unlock_irq(&self->pi_lock);
> +
> + chill_time = ktime_set(0, NSEC_PER_MSEC);
> +
> 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;
> - __set_current_state_no_track(saved_state);
> +
> + raw_spin_lock_irq(&self->pi_lock);
> + __set_current_state_no_track(self->saved_state);
> + self->saved_state = TASK_RUNNING;
> + raw_spin_unlock_irq(&self->pi_lock);
> }
> EXPORT_SYMBOL(cpu_chill);
> #endif
>
> Sebastian
