[PATCH 17/31] cpuset: Propagate cpuset isolation update to workqueue through housekeeping

[Chen Ridong]

On 2025/11/6 5:03, Frederic Weisbecker wrote:
> Until now, cpuset would propagate isolated partition changes to
> workqueues so that unbound workers get properly reaffined.
> 
> Since housekeeping now centralizes, synchronize and propagates isolation
> cpumask changes, perform the work from that subsystem for consolidation
> and consistency purposes.
> 
> For simplification purpose, the target function is adapted to take the
> new housekeeping mask instead of the isolated mask.
> 
> Suggested-by: Tejun Heo <tj at kernel.org>
> Signed-off-by: Frederic Weisbecker <frederic at kernel.org>
> ---
>  include/linux/workqueue.h |  2 +-
>  init/Kconfig              |  1 +
>  kernel/cgroup/cpuset.c    | 14 ++++++--------
>  kernel/sched/isolation.c  |  4 +++-
>  kernel/workqueue.c        | 17 ++++++++++-------
>  5 files changed, 21 insertions(+), 17 deletions(-)
> 
> diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
> index dabc351cc127..a4749f56398f 100644
> --- a/include/linux/workqueue.h
> +++ b/include/linux/workqueue.h
> @@ -588,7 +588,7 @@ struct workqueue_attrs *alloc_workqueue_attrs_noprof(void);
>  void free_workqueue_attrs(struct workqueue_attrs *attrs);
>  int apply_workqueue_attrs(struct workqueue_struct *wq,
>  			  const struct workqueue_attrs *attrs);
> -extern int workqueue_unbound_exclude_cpumask(cpumask_var_t cpumask);
> +extern int workqueue_unbound_housekeeping_update(const struct cpumask *hk);
>  
>  extern bool queue_work_on(int cpu, struct workqueue_struct *wq,
>  			struct work_struct *work);
> diff --git a/init/Kconfig b/init/Kconfig
> index cab3ad28ca49..a1b3a3b66bfc 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1247,6 +1247,7 @@ config CPUSETS
>  	bool "Cpuset controller"
>  	depends on SMP
>  	select UNION_FIND
> +	select CPU_ISOLATION
>  	help
>  	  This option will let you create and manage CPUSETs which
>  	  allow dynamically partitioning a system into sets of CPUs and
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index b04a4242f2fa..ea102e4695a5 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -1392,7 +1392,7 @@ static bool partition_xcpus_del(int old_prs, struct cpuset *parent,
>  	return isolcpus_updated;
>  }
>  
> -static void update_unbound_workqueue_cpumask(bool isolcpus_updated)
> +static void update_housekeeping_cpumask(bool isolcpus_updated)
>  {
>  	int ret;
>  
> @@ -1401,8 +1401,6 @@ static void update_unbound_workqueue_cpumask(bool isolcpus_updated)
>  	if (!isolcpus_updated)
>  		return;
>  
> -	ret = workqueue_unbound_exclude_cpumask(isolated_cpus);
> -	WARN_ON_ONCE(ret < 0);
>  	ret = housekeeping_update(isolated_cpus, HK_TYPE_DOMAIN);
>  	WARN_ON_ONCE(ret < 0);
>  }
> @@ -1558,7 +1556,7 @@ static int remote_partition_enable(struct cpuset *cs, int new_prs,
>  	list_add(&cs->remote_sibling, &remote_children);
>  	cpumask_copy(cs->effective_xcpus, tmp->new_cpus);
>  	spin_unlock_irq(&callback_lock);
> -	update_unbound_workqueue_cpumask(isolcpus_updated);
> +	update_housekeeping_cpumask(isolcpus_updated);
>  	cpuset_force_rebuild();
>  	cs->prs_err = 0;
>  
> @@ -1599,7 +1597,7 @@ static void remote_partition_disable(struct cpuset *cs, struct tmpmasks *tmp)
>  	compute_excpus(cs, cs->effective_xcpus);
>  	reset_partition_data(cs);
>  	spin_unlock_irq(&callback_lock);
> -	update_unbound_workqueue_cpumask(isolcpus_updated);
> +	update_housekeeping_cpumask(isolcpus_updated);
>  	cpuset_force_rebuild();
>  
>  	/*
> @@ -1668,7 +1666,7 @@ static void remote_cpus_update(struct cpuset *cs, struct cpumask *xcpus,
>  	if (xcpus)
>  		cpumask_copy(cs->exclusive_cpus, xcpus);
>  	spin_unlock_irq(&callback_lock);
> -	update_unbound_workqueue_cpumask(isolcpus_updated);
> +	update_housekeeping_cpumask(isolcpus_updated);
>  	if (adding || deleting)
>  		cpuset_force_rebuild();
>  
> @@ -2027,7 +2025,7 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd,
>  		WARN_ON_ONCE(parent->nr_subparts < 0);
>  	}
>  	spin_unlock_irq(&callback_lock);
> -	update_unbound_workqueue_cpumask(isolcpus_updated);
> +	update_housekeeping_cpumask(isolcpus_updated);
>  
>  	if ((old_prs != new_prs) && (cmd == partcmd_update))
>  		update_partition_exclusive_flag(cs, new_prs);
> @@ -3047,7 +3045,7 @@ static int update_prstate(struct cpuset *cs, int new_prs)
>  	else if (isolcpus_updated)
>  		isolated_cpus_update(old_prs, new_prs, cs->effective_xcpus);
>  	spin_unlock_irq(&callback_lock);
> -	update_unbound_workqueue_cpumask(isolcpus_updated);
> +	update_housekeeping_cpumask(isolcpus_updated);
>  

The patch [1] has been applied to cgroup/for-next, you may have to adapt it.

[1]: https://lore.kernel.org/cgroups/20251105043848.382703-6-longman@redhat.com/T/#u

-- 
Best regards,
Ridong