linux-kernel - [PATCH v2] sched/fair: Fix cfs_rq_is

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Date:   Fri, 18 Aug 2023 21:21:48 +0800
From:   chengming.zhou@...ux.dev
To:     mingo@...hat.com, peterz@...radead.org, ycliang@...estech.com
Cc:     juri.lelli@...hat.com, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, bristot@...hat.com, vschneid@...hat.com,
        zhouchengming@...edance.com, linux-kernel@...r.kernel.org
Subject: [PATCH v2] sched/fair: Fix cfs_rq_is_decayed() on !SMP

From: Chengming Zhou <zhouchengming@...edance.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@...estech.com>
Signed-off-by: Chengming Zhou <zhouchengming@...edance.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