Re: [PATCH v11 7/8] cgroup/cpuset: Update description of cpuset.cpus.partition in cgroup-v2.rst

Tejun Heo
2022-06-13T19:37:46Z

Hello,

On Mon, Jun 13, 2022 at 07:55:49PM +0200, Michal Koutný wrote:
> On Mon, Jun 13, 2022 at 07:28:25AM -1000, Tejun Heo <tj@kernel.org> wrote:
> > I see. Is this part even necessary? All the .cpus files of the siblings are
> > owned by the parent who's responsible for configuring both the mode that the
> > cgroup subtree is gonna be in and their cpumasks.
>
> Do you mean such an example:
>
> parent cpuset.cpus=SET (root) cpuset.cpus.partition=isolated
> `- child_1 cpuset.cpus=partition_of(SET) (root) cpuset.cpus.partition=isolated
> `- ...
> `- child_n cpuset.cpus=partition_of(SET) (root) cpuset.cpus.partition=isolated
> ?
>
> I don't think child_*/cpuset.cpus must be owned by root.

I meant the parent.

> Actually, the root would only configure the parent, i.e.
> parent/cpuset.cpus (whose changes would be disallowed to the
> unprivileged tasks) and the distribution among siblings would up to the
> whatever runs below.
>
> > Given that all the other errors it can make are notified through
> > "invalid (REASON)" in the mode file, wouldn't it fit better to notify
> > cpus configuration error the same way too?
>
> Do you suggest that a write into child_*/cpuset.cpus that'd not be
> exclusive wrt a sibling would result in an error string in
> parent/cpuset.cpus.partition?

Yeah, I don't know why this part is different from any other errors that the
parent can make.

Thanks.

--
tejun