Re: [patch V3 20/20] sched/mmcid: Switch over to the new mechanism

[Mathieu Desnoyers]

On 2025-10-29 09:09, Thomas Gleixner wrote:

> @@ -10702,10 +10758,43 @@ void sched_mm_cid_exit(struct task_struc
>   
>   	if (!mm || !t->mm_cid.active)
>   		return;
> +	/*
> +	 * Ensure that only one instance is doing MM CID operations within
> +	 * a MM. The common case is uncontended. The rare fixup case adds
> +	 * some overhead.
> +	 */
> +	scoped_guard(mutex, &mm->mm_cid.mutex) {

When exiting from a mm where mm->mm_cid.users == 1 (read with
READ_ONCE()), can we do this without holding the mutex as an
optimization ?

> +	 * Synchronize eventally pending work to ensure that there are no

eventually

Thanks,

Mathieu

--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com