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

From: Frederic Weisbecker <[email-masked]>
Date: Tue, 23 Dec 2025 16:17:55 +0100

Le Thu, Nov 06, 2025 at 08:55:42AM +0800, Chen Ridong a écrit :
> 
> 
> 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 <[email-masked]>
> > Signed-off-by: Frederic Weisbecker <[email-masked]>
> > ---
> >  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/[email-masked]/T/#u

Right, I just waited for -rc1 to pop-up before doing that.
v5 will follow shortly.

Thanks.

> -- 
> Best regards,
> Ridong

-- 
Frederic Weisbecker
SUSE Labs