6.4-stable review patch. If anyone has any objections, please let me know.
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From: Waiman Long longman@redhat.com
[ Upstream commit c8c926200c55454101f072a4b16c9ff5b8c9e56f ]
Since commit f28e22441f35 ("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: f28e22441f35 ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/cgroup/cpuset.c | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 2c76fcd9f0bcb..7c5153273c1a8 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1611,11 +1611,16 @@ 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; } @@ -1698,6 +1703,20 @@ 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. @@ -3245,6 +3264,14 @@ 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))