On Tue 02-02-21 13:47:43, Johannes Weiner wrote: > Rstat currently only supports the default hierarchy in cgroup2. In > order to replace memcg's private stats infrastructure - used in both > cgroup1 and cgroup2 - with rstat, the latter needs to support cgroup1. > > The initialization and destruction callbacks for regular cgroups are > already in place. Remove the cgroup_on_dfl() guards to handle cgroup1. > > The initialization of the root cgroup is currently hardcoded to only > handle cgrp_dfl_root.cgrp. Move those callbacks to cgroup_setup_root() > and cgroup_destroy_root() to handle the default root as well as the > various cgroup1 roots we may set up during mounting. > > The linking of css to cgroups happens in code shared between cgroup1 > and cgroup2 as well. Simply remove the cgroup_on_dfl() guard. > > Linkage of the root css to the root cgroup is a bit trickier: per > default, the root css of a subsystem controller belongs to the default > hierarchy (i.e. the cgroup2 root). When a controller is mounted in its > cgroup1 version, the root css is stolen and moved to the cgroup1 root; > on unmount, the css moves back to the default hierarchy. Annotate > rebind_subsystems() to move the root css linkage along between roots. I am not familiar with rstat API and from this patch it is not really clear to me how does it deal with memcg v1 use_hierarchy oddness. -- Michal Hocko SUSE Labs
