cgroup/cpuset: Support multiple destination cpusets for cpuset_*attach()

The only case where the cgroup_taskset structure requires task migration
to multiple cpusets is when enabling a cpuset controller in cgroup v2
where the newly created child cpusets inherits the same effective CPUs
and memory nodes from the parent. In that case, task migration can happen
directly with no update to tasks' CPU and memory nodes assignment and no
further work needed from the cpuset side except updating nr_deadline_tasks
when DL tasks are involved and setting old_mems_allowed in the child
cpusets.

Do that by tracking all the destination cpusets with a new dst_cs_head
singly linked list. The reset_migrate_dl_data() function is integrated
into clear_attach_data() so that it can be used for both source and
destination cpusets.

A warning will be printed if there are multiple destination cpusets but
it is not on default hierarchy or when the CPUs or memory nodes change.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

0 files changed, 0 insertions, 0 deletions