Re: [PATCH -next RFC 06/16] cpuset: introduce local_partition_enable()

[Waiman Long <llong@redhat.com>]

On 9/28/25 3:12 AM, Chen Ridong wrote:
> From: Chen Ridong <chenridong@huawei.com>
>
> The partition_enable() function introduced in the previous patch can be
> reused to enable local partitions.
>
> First, partition_enable() was enhanced to support local partition enabling
> by properly handling parent's nr_subparts counter and adding notification
> operations.
>
> Then, the local_partition_enable() function is introduced, which factors
> out the local partition enablement logic from
> update_parent_effective_cpumask(). After passing local partition validation
> checks, it delegates to partition_enable() to complete the partition setup.
>
> This refactoring creates a clear separation between local and remote
> partition operations while maintaining code reuse through the shared
> partition_enable() infrastructure.
>
> Signed-off-by: Chen Ridong <chenridong@huawei.com>
> ---
>   kernel/cgroup/cpuset.c | 111 +++++++++++++++++++++++++++--------------
>   1 file changed, 74 insertions(+), 37 deletions(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 0e2f95daf459..154992cdfe9a 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -1539,6 +1539,7 @@ static void partition_enable(struct cpuset *cs, struct cpuset *parent,
>   				 int new_prs, struct cpumask *new_excpus)
>   {
>   	bool isolcpus_updated;
> +	int old_prs;
>   
>   	lockdep_assert_held(&cpuset_mutex);
>   	WARN_ON_ONCE(new_prs <= 0);
> @@ -1547,15 +1548,21 @@ static void partition_enable(struct cpuset *cs, struct cpuset *parent,
>   	if (cs->partition_root_state == new_prs)
>   		return;
>   
> +	old_prs = cs->partition_root_state;
>   	spin_lock_irq(&callback_lock);
>   	/* enable partition should only add exclusive cpus */
>   	isolcpus_updated = partition_xcpus_add(new_prs, parent, new_excpus);
> -	list_add(&cs->remote_sibling, &remote_children);
> +	/* enable remote partition */
> +	if (!parent)
> +		list_add(&cs->remote_sibling, &remote_children);
> +	else if (!is_partition_valid(cs))
> +		parent->nr_subparts += 1;
>   	cpumask_copy(cs->effective_xcpus, new_excpus);
>   	partition_state_update(cs, new_prs, PERR_NONE);
>   	spin_unlock_irq(&callback_lock);
>   	update_unbound_workqueue_cpumask(isolcpus_updated);
>   	cpuset_force_rebuild();
> +	notify_partition_change(cs, old_prs);
>   }

As commented in an earlier patch, the partition_enable() chnage should 
be moved there.

Cheers,
Longman