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cgroup/cpuset: Inherit parent's load balance state in v2 

Since commit f28e22441f ("cgroup/cpuset: Add a new isolated
cpus.partition type"), the CS_SCHED_LOAD_BALANCE bit of a v2 cpuset
can be on or off. The child cpusets of a partition root must have the
same setting as its parent or it may screw up the rebuilding of sched
domains. Fix this problem by making sure the a child v2 cpuset will
follows its parent cpuset load balance state unless the child cpuset
is a new partition root itself.

Fixes: f28e22441f ("cgroup/cpuset: Add a new isolated cpus.partition type")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Waiman Long 2023-06-27 10:35:00 -04:00 committed by Tejun Heo
parent 868f87b375
commit c8c926200c
1 changed files with 30 additions and 3 deletions
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33
kernel/cgroup/cpuset.c
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@ -1588,11 +1588,16 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
}
/*
* Skip the whole subtree if the cpumask remains the same
* and has no partition root state and force flag not set.
* Skip the whole subtree if
* 1) the cpumask remains the same,
* 2) has no partition root state,
* 3) force flag not set, and
* 4) for v2 load balance state same as its parent.
*/
if (!cp->partition_root_state && !force &&
cpumask_equal(tmp->new_cpus, cp->effective_cpus)) {
cpumask_equal(tmp->new_cpus, cp->effective_cpus) &&
(!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) ||
(is_sched_load_balance(parent) == is_sched_load_balance(cp)))) {
pos_css = css_rightmost_descendant(pos_css);
continue;
}
@ -1675,6 +1680,20 @@ update_parent_subparts:
update_tasks_cpumask(cp, tmp->new_cpus);
/*
* On default hierarchy, inherit the CS_SCHED_LOAD_BALANCE
* from parent if current cpuset isn't a valid partition root
* and their load balance states differ.
*/
if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
!is_partition_valid(cp) &&
(is_sched_load_balance(parent) != is_sched_load_balance(cp))) {
if (is_sched_load_balance(parent))
set_bit(CS_SCHED_LOAD_BALANCE, &cp->flags);
else
clear_bit(CS_SCHED_LOAD_BALANCE, &cp->flags);
}
/*
* On legacy hierarchy, if the effective cpumask of any non-
* empty cpuset is changed, we need to rebuild sched domains.
@ -3235,6 +3254,14 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
cs->use_parent_ecpus = true;
parent->child_ecpus_count++;
}
/*
* For v2, clear CS_SCHED_LOAD_BALANCE if parent is isolated
*/
if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
!is_sched_load_balance(parent))
clear_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
spin_unlock_irq(&callback_lock);
if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))