Re: [PATCH v4 sched_ext/for-7.3 01/40] sched_ext: Record an error on errno-only sub-enable failure

[Andrea Righi]

On Wed, Jul 08, 2026 at 11:23:50AM -1000, Tejun Heo wrote:
> scx_sub_enable_workfn() has several failure paths that only return an errno
> (e.g. -ENOMEM from an allocation) and jump to err_disable without calling
> scx_error(). scx_flush_disable_work() runs the disable, and thus ops.exit(),
> only when an error has been recorded, so an errno-only failure leaves the
> half-initialized sub-scheduler linked.
> 
> Record an error at the err_disable sink so every errno-only failure runs the
> disable path.
> 
> Fixes: ebeca1f930ea ("sched_ext: Introduce cgroup sub-sched support")
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>

Reviewed-by: Andrea Righi <arighi@xxxxxxxxxx>

Thanks,
-Andrea

> ---
>  kernel/sched/ext/sub.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/kernel/sched/ext/sub.c b/kernel/sched/ext/sub.c
> index 050420427273..ce76ae141e0a 100644
> --- a/kernel/sched/ext/sub.c
> +++ b/kernel/sched/ext/sub.c
> @@ -570,6 +570,12 @@ void scx_sub_enable_workfn(struct kthread_work *work)
>  	percpu_up_write(&scx_fork_rwsem);
>  err_disable:
>  	mutex_unlock(&scx_enable_mutex);
> +	/*
> +	 * Some enable failures only return an errno (e.g. -ENOMEM from an
> +	 * allocation) without calling scx_error(). Record it so
> +	 * scx_flush_disable_work() runs the disable and ops.exit() fires.
> +	 */
> +	scx_error(sch, "scx_sub_enable() failed (%d)", ret);
>  	scx_flush_disable_work(sch);
>  	cmd->ret = 0;
>  }
> -- 
> 2.54.0
>