Re: [PATCH] sched/topology: Add a cpus_read_lock to partition_sched_domains()

[Sebastian Andrzej Siewior]

On 2026-08-12 20:54:49 [+0800], Chen, Yu C wrote:
> Hi Sebastian,
Hi,

> > --- a/kernel/sched/topology.c
> > +++ b/kernel/sched/topology.c
> > @@ -3498,6 +3498,7 @@ static void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new
> >   void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
> >   			     struct sched_domain_attr *dattr_new)
> >   {
> > +	guard(cpus_read_lock)();
> >   	sched_domains_mutex_lock();
> >   	partition_sched_domains_locked(ndoms_new, doms_new, dattr_new);
> >   	sched_domains_mutex_unlock();
> 
> Thanks for taking a look at this issue. I found that there is a comment
> around
> partition_sched_domains() says: "Call with hotplug lock held"
> Not sure if the caller of partition_sched_domains() rather than
> partition_sched_domains()
> should grab the cpuhotplug lock? I guess the issue is triggered when
How did I miss that part?

> CONFIG_CPUSETS=n, in this case rebuild_sched_domains() will not grab
> cpuhotplug lock, should we add guard(cpus_read_lock) in
> rebuild_sched_domains()
> instead?

Let me look…

> thanks,
> Chenyu

Sebastian