Commit c8c92620 authored by Waiman Long's avatar Waiman Long Committed by Tejun Heo
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cgroup/cpuset: Inherit parent's load balance state in v2 



Since commit f28e2244 ("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: f28e2244 ("cgroup/cpuset: Add a new isolated cpus.partition type")
Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 868f87b3

kernel/cgroup/cpuset.c

+30 −3
Original line number Diff line number Diff line
@@ -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 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp, 


		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))