6.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Juri Lelli <juri.lelli@xxxxxxxxxx> commit c0f78fd5edcf29b2822ac165f9248a6c165e8554 upstream. update_tasks_root_domain currently iterates over all tasks even if no DEADLINE task is present on the cpuset/root domain for which bandwidth accounting is being rebuilt. This has been reported to introduce 10+ ms delays on suspend-resume operations. Skip the costly iteration for cpusets that don't contain DEADLINE tasks. Reported-by: Qais Yousef (Google) <qyousef@xxxxxxxxxxx> Link: https://lore.kernel.org/lkml/20230206221428.2125324-1-qyousef@xxxxxxxxxxx/ Signed-off-by: Juri Lelli <juri.lelli@xxxxxxxxxx> Reviewed-by: Waiman Long <longman@xxxxxxxxxx> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx> Signed-off-by: Qais Yousef (Google) <qyousef@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- kernel/cgroup/cpuset.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1092,6 +1092,9 @@ static void dl_update_tasks_root_domain( struct css_task_iter it; struct task_struct *task; + if (cs->nr_deadline_tasks == 0) + return; + css_task_iter_start(&cs->css, 0, &it); while ((task = css_task_iter_next(&it)))
