On 6/16/21 4:57 PM, Tejun Heo wrote:
Hello,
On Thu, Jun 03, 2021 at 05:24:14PM -0400, Waiman Long wrote:
@@ -2181,6 +2192,13 @@ static int cpuset_can_attach(struct cgroup_taskset *tset)
(cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
goto out_unlock;
+ /*
+ * On default hierarchy, task cannot be moved to a cpuset with empty
+ * effective cpus.
+ */
+ if (is_in_v2_mode() && cpumask_empty(cs->effective_cpus))
+ goto out_unlock;
+
This is inconsistent with how other events which leave a root partition
empty is handled. Woudln't it be more consistent to switch the parent to
PRS_ERROR and behave accordingly but allow it to have valid child roots?
From my point of view, PRS_ERROR is used when cpus are gone because of
cpu hotplug (offline). It can be a temporary condition that will be
corrected later on. I don't want to use PRS_ERROR for the particular
case that the users have explicitly distributed out all the cpus to
child partitions. I will clarify it in the next version and double check
to make sure that this rule is consistently apply.
Thanks,
Longman
