Re: [PATCH 5/6] cgroup/cpuset: optimize cpuset_mems_allowed_intersects()

[Waiman Long]

On 5/14/24 12:50, Tejun Heo wrote:
> On Tue, May 14, 2024 at 12:47:59PM -0400, Waiman Long wrote:
> > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> > > index 4237c8748715..47ed206d4890 100644
> > > --- a/kernel/cgroup/cpuset.c
> > > +++ b/kernel/cgroup/cpuset.c
> > > @@ -5010,6 +5010,9 @@ EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
> > >    int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
> > >    				   const struct task_struct *tsk2)
> > >    {
> > > +	if (tsk1 == tsk2)
> > > +		return 1;
> > > +
> > >    	return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
> > >    }
> > Reviewed-by: Waiman Long <longman@xxxxxxxxxx>
> I'm not sure this is worth the added code.

Yes, I do have a second thought afterward. The only caller of 
cpuset_mems_allowed_intersects() is oom_cpuset_eligible() in 
mm/oom_kill.c. So I believe a better fix is to avoid calling 
cpuset_mems_allowed_intersects() there if current == tsk.

Cheers,
Longman