Re: The "clockevents: Prevent timer interrupt starvation" patch causes lockups

[Hanabishi]

On 14/04/2026 20:55, Thomas Gleixner wrote:
> The one below should cover all possible holes.
>
> Thanks,
>
>          tglx
> ---
> diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
> index b4d730604972..5e22697b098d 100644
> --- a/kernel/time/clockevents.c
> +++ b/kernel/time/clockevents.c
> @@ -94,6 +94,9 @@ static int __clockevents_switch_state(struct clock_event_device *dev,
>   	if (dev->features & CLOCK_EVT_FEAT_DUMMY)
>   		return 0;
>   
> +	/* On state transitions clear the forced flag unconditionally */
> +	dev->next_event_forced = 0;
> +
>   	/* Transition with new state-specific callbacks */
>   	switch (state) {
>   	case CLOCK_EVT_STATE_DETACHED:
> @@ -366,8 +369,10 @@ int clockevents_program_event(struct clock_event_device *dev, ktime_t expires, b
>   	if (delta > (int64_t)dev->min_delta_ns) {
>   		delta = min(delta, (int64_t) dev->max_delta_ns);
>   		cycles = ((u64)delta * dev->mult) >> dev->shift;
> -		if (!dev->set_next_event((unsigned long) cycles, dev))
> +		if (!dev->set_next_event((unsigned long) cycles, dev)) {
> +			dev->next_event_forced = 0;
>   			return 0;
> +		}
>   	}
>   
>   	if (dev->next_event_forced)
> diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
> index 7e57fa31ee26..115e0bf01276 100644
> --- a/kernel/time/tick-broadcast.c
> +++ b/kernel/time/tick-broadcast.c
> @@ -108,6 +108,7 @@ static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu)
>   
>   static void tick_oneshot_wakeup_handler(struct clock_event_device *wd)
>   {
> +	wd->next_event_forced = 0;
>   	/*
>   	 * If we woke up early and the tick was reprogrammed in the
>   	 * meantime then this may be spurious but harmless.

Ok, it does fix the problem! Thank you.
The patch itself does not apply cleanly for 7.0 though and I had to adapt it a bit.