[PATCH v4 4/5] cgroup/cpuset: Make cpuset_attach_task() skip subpartitions CPUs for top_cpuset

From: Waiman Long
Date: Tue Apr 11 2023 - 09:38:04 EST


It is found that attaching a task to the top_cpuset does not currently
ignore CPUs allocated to subpartitions in cpuset_attach_task(). So the
code is changed to fix that.

Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
Reviewed-by: Michal Koutný <mkoutny@xxxxxxxx>
---
kernel/cgroup/cpuset.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 132cdae4f03c..e4ca2dd2b764 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2540,7 +2540,8 @@ static void cpuset_attach_task(struct cpuset *cs, struct task_struct *task)
if (cs != &top_cpuset)
guarantee_online_cpus(task, cpus_attach);
else
- cpumask_copy(cpus_attach, task_cpu_possible_mask(task));
+ cpumask_andnot(cpus_attach, task_cpu_possible_mask(task),
+ cs->subparts_cpus);
/*
* can_attach beforehand should guarantee that this doesn't
* fail. TODO: have a better way to handle failure here
--
2.31.1