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@redhat.com>
---
 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 f6d5614982d7..2367de611c42 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2530,7 +2530,8 @@ 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

Hi.

On Fri, Mar 31, 2023 at 10:50:44AM -0400, Waiman Long <longman@redhat.com> wrote:
> 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@redhat.com>
> ---
>  kernel/cgroup/cpuset.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Reviewed-by: Michal Koutný <mkoutny@suse.com>