On Wed, Aug 24, 2022 at 04:18:27PM +0800, Chengming Zhou wrote:

cgroup_psi() can't return psi_group for root cgroup, so we have many
open code "psi = cgroup_ino(cgrp) == 1 ? &psi_system : cgrp->psi".

This patch move cgroup_psi() definition to <linux/psi.h>, in which
we can return psi_system for root cgroup, so can handle all cgroups.

Signed-off-by: Chengming Zhou <redacted>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>