From: Chengming Zhou <zhouchengming@bytedance.com>

We don't need to maintain per-queue leaf_cfs_rq_list on !SMP, since
it's used for cfs_rq load tracking & balance on SMP.

But sched debug interface use it to print per-cfs_rq stats, which
maybe better to change to use walk_tg_tree_from() instead.

This patch just fix the !SMP version cfs_rq_is_decayed(), so the
per-queue leaf_cfs_rq_list is also maintained correctly on !SMP,
to fix the warning in assert_list_leaf_cfs_rq().

Fixes: 0a00a354644e ("sched/fair: Delete useless condition in tg_unthrottle_up()")
Reported-by: Leo Liang <ycliang@andestech.com>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
 kernel/sched/fair.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a80a73909dc2..05e004515fde 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4654,7 +4654,7 @@ static inline void update_misfit_status(struct task_struct *p, struct rq *rq)
 
 static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
 {
-	return true;
+	return !(cfs_rq->nr_running);
 }
 
 #define UPDATE_TG	0x0
-- 
2.41.0

On Fri, 18 Aug 2023 at 15:22, <chengming.zhou@linux.dev> wrote:
>
> From: Chengming Zhou <zhouchengming@bytedance.com>
>
> We don't need to maintain per-queue leaf_cfs_rq_list on !SMP, since
> it's used for cfs_rq load tracking & balance on SMP.
>
> But sched debug interface use it to print per-cfs_rq stats, which
> maybe better to change to use walk_tg_tree_from() instead.
>
> This patch just fix the !SMP version cfs_rq_is_decayed(), so the
> per-queue leaf_cfs_rq_list is also maintained correctly on !SMP,
> to fix the warning in assert_list_leaf_cfs_rq().
>
> Fixes: 0a00a354644e ("sched/fair: Delete useless condition in tg_unthrottle_up()")
> Reported-by: Leo Liang <ycliang@andestech.com>
> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>

Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>

> ---
>  kernel/sched/fair.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index a80a73909dc2..05e004515fde 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4654,7 +4654,7 @@ static inline void update_misfit_status(struct task_struct *p, struct rq *rq)
>
>  static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
>  {
> -       return true;
> +       return !(cfs_rq->nr_running);
>  }
>
>  #define UPDATE_TG      0x0
> --
> 2.41.0
>