Re: [PATCH v6 06/12] smp: Enable preemption early in smp_call_function_many_cond

[Sebastian Andrzej Siewior]

On 2026-05-28 23:13:32 [+0800], Chuyi Zhou wrote:
> --- a/kernel/smp.c
> +++ b/kernel/smp.c
> @@ -953,6 +952,17 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
>  		local_irq_restore(flags);
>  	}
>  
> +	/*
> +	 * Waiting for completion can take time especially with many CPUs.
> +	 * On a PREEMPTIBLE kernel a per-task cpumask is used to track CPUs

I wouldn't use PREEMPTIBLE. It is PREEMPT which short for
CONFIG_PREEMPT. PREEMPTIBLE is not a distinct entity since "preemptible"
can be changed at runtime.

> +	 * with pending IPI request. This allows to enable preemption and
> +	 * potentially wait while allowing task preemption. On a !PREEMPTIBLE
> +	 * the cpumask is shared and the call must block until completion to
> +	 * avoid modifications by a another caller on this CPU.
> +	 */
> +	if (task_mask)
> +		put_cpu();
> +
>  	if (run_remote && wait) {
>  		for_each_cpu(cpu, cpumask) {
>  			call_single_data_t *csd;

Other than that, 

Reviewed-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>

Sebastian