Re: [PATCH] sched/ext: fix cpumask leak in scx_init() error path

[Cheng-Yang Chou]

Hi Andrea, Koba,

On Wed, Apr 08, 2026 at 07:34:19PM +0200, Andrea Righi wrote:
> > +++ b/kernel/sched/ext.c
> > @@ -9662,9 +9662,14 @@ static int __init scx_init(void)
> >  		return ret;
> >  	}
> >  
> > -	if (!alloc_cpumask_var(&scx_bypass_lb_donee_cpumask, GFP_KERNEL) ||
> > -	    !alloc_cpumask_var(&scx_bypass_lb_resched_cpumask, GFP_KERNEL)) {
> > -		pr_err("sched_ext: Failed to allocate cpumasks\n");
> > +	if (!alloc_cpumask_var(&scx_bypass_lb_donee_cpumask, GFP_KERNEL)) {
> > +		pr_err("sched_ext: Failed to allocate donee cpumask\n");
> > +		return -ENOMEM;
> > +	}
> > +
> > +	if (!alloc_cpumask_var(&scx_bypass_lb_resched_cpumask, GFP_KERNEL)) {
> > +		pr_err("sched_ext: Failed to allocate resched cpumask\n");
> > +		free_cpumask_var(scx_bypass_lb_donee_cpumask);
> 
> We should probably do a proper teardown of the other stuff as well at some point
> (sysfs group, kset, PM notifier, etc.), but this looks good to me.
> 
> >  		return -ENOMEM;
> >  	}

Should kset_unregister() also be called in these error paths?

scx_kset is allocated earlier in scx_init() and none of the failure
paths after that call kset_unregister()

	scx_kset = kset_create_and_add("sched_ext", &scx_uevent_ops, kernel_kobj);
	...
	ret = sysfs_create_group(&scx_kset->kobj, &scx_global_attr_group);
	if (ret < 0) {
		pr_err("sched_ext: Failed to add global attributes\n");
+		kset_unregister(scx_kset);
		return ret;	/* scx_kset leaked */
	}

    if (!alloc_cpumask_var(&scx_bypass_lb_donee_cpumask, GFP_KERNEL)) {
		pr_err("sched_ext: Failed to allocate donee cpumask\n");
+		kset_unregister(scx_kset);
		return -ENOMEM;	/* scx_kset leaked */
	}

	if (!alloc_cpumask_var(&scx_bypass_lb_resched_cpumask, GFP_KERNEL)) {
		pr_err("sched_ext: Failed to allocate resched cpumask\n");
		free_cpumask_var(scx_bypass_lb_donee_cpumask);
+		kset_unregister(scx_kset);
		return -ENOMEM;	/* scx_kset leaked */
	}
-- 
Thanks,
Cheng-Yang