Commit 411d3ef1 authored by Tejun Heo's avatar Tejun Heo
Browse files

sched_ext: Unregister sub_kset on scheduler disable 



When ops.sub_attach is set, scx_alloc_and_add_sched() creates sub_kset as a
child of &sch->kobj, which pins the parent with its own reference. The
disable paths never call kset_unregister(), so the final kobject_put() in
bpf_scx_unreg() leaves a stale reference and scx_kobj_release() never runs,
leaking the whole struct scx_sched on every load/unload cycle.

Unregister sub_kset in scx_root_disable() and scx_sub_disable() before
kobject_del(&sch->kobj).

Fixes: ebeca1f9 ("sched_ext: Introduce cgroup sub-sched support")
Reported-by: default avatarChris Mason <clm@meta.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reviewed-by: default avatarAndrea Righi <arighi@nvidia.com>
parent bd2d7645

kernel/sched/ext.c

+6 −0
Original line number Diff line number Diff line
@@ -5721,6 +5721,8 @@ static void scx_sub_disable(struct scx_sched *sch) 


	if (sch->ops.exit)

		SCX_CALL_OP(sch, exit, NULL, sch->exit_info);

	if (sch->sub_kset)

		kset_unregister(sch->sub_kset);

	kobject_del(&sch->kobj);

}

#else	/* CONFIG_EXT_SUB_SCHED */
@@ -5852,6 +5854,10 @@ static void scx_root_disable(struct scx_sched *sch) 
	 * could observe an object of the same name still in the hierarchy when

	 * the next scheduler is loaded.

	 */

#ifdef CONFIG_EXT_SUB_SCHED

	if (sch->sub_kset)

		kset_unregister(sch->sub_kset);

#endif

	kobject_del(&sch->kobj);



	free_kick_syncs();