Re: [PATCH 2/2] cgroup: Skip subtree root in cgroup_update_dfl_csses()

[Michal Koutný]

On Wed, Jul 27, 2022 at 08:58:15PM -0400, Waiman Long <longman@xxxxxxxxxx> wrote:
> The cgroup_update_dfl_csses() function updates css associations when a
> cgroup's subtree_control file is modified. Any changes made to a cgroup's
> subtree_control file, however, will only affect its descendants but not
> the cgroup itself. 

I find this correct.

> So there is no point in migrating csses associated with that cgroup.
> We can skip them instead.

Alone it's not such a big win but it componds with the recent Tejun's
threadgroup_rwsem elision.

> ---
>  kernel/cgroup/cgroup.c | 9 +++++++++
>  1 file changed, 9 insertions(+)

Feel free to have
Reviewed-by: Michal Koutný <mkoutny@xxxxxxxx>