Re: [PATCH] cgroup: Don't expose dead tasks in cgroup

[Tejun Heo <tj@kernel.org>]

Hello, Seb.

On Mon, Mar 02, 2026 at 01:07:38PM +0100, Sebastian Andrzej Siewior wrote:
> Tejun, with this change, would it be okay to
> - replace the irq-work with kworker? With this change it should address
>   your concern regarding "run in definite time" as mentioned in [0]. So
>   it might be significantly delayed but it shouldn't be visible.
>   This would lift the restriction that a irq-work needs to run on this
>   CPU and the kworker could run on any CPU. 

Yeah, that's fine.

> - would it be okay to treat RT and !RT equally here (and do this delayed
>   cgroup_task_dead() in both cases)

I don't see why we'd bounce on !RT. Are there any benefits?

> @@ -5283,6 +5283,11 @@ static void *cgroup_procs_start(struct seq_file *s, loff_t *pos)
>  
>  static int cgroup_procs_show(struct seq_file *s, void *v)
>  {
> +	struct task_struct *tsk = v;
> +
> +	if (READ_ONCE(tsk->__state) & TASK_DEAD)
> +		return 0;

Does this actually close the window for systemd through operation ordering
or does it just reduce the race window?

Thanks.

-- 
tejun