linux-kernel - Re: [PATCH v6 2/2] sched/rt: Trying to push current task when target disable migrating

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Message-ID: <5f0d6bef-9e9e-7083-9657-ae5e6dd10d2a@arm.com>
Date:   Wed, 13 Jul 2022 12:02:42 +0200
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Schspa Shi <schspa@...il.com>, mingo@...hat.com,
        peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, rostedt@...dmis.org,
        bsegall@...gle.com, mgorman@...e.de, bristot@...hat.com,
        vschneid@...hat.com
Cc:     linux-kernel@...r.kernel.org, zhaohui.shi@...izon.ai
Subject: Re: [PATCH v6 2/2] sched/rt: Trying to push current task when target
 disable migrating

On 12/07/2022 17:05, Schspa Shi wrote:

[...]

> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index 7bd3e6ecbe45e..e2d7b085a93d9 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -2136,6 +2136,12 @@ static int push_rt_task(struct rq *rq, bool pull)
>  		 */
>  		task = pick_next_pushable_task(rq);
>  		if (task == next_task) {
> +			/*
> +			 * If next task has now disabled migrating, see if we
> +			 * can push the current task.
> +			 */
> +			if (unlikely(is_migration_disabled(task)))

Doesn't this need a `put_task_struct(next_task)`?

> +				goto retry;
>  			/*
>  			 * The task hasn't migrated, and is still the next
>  			 * eligible task, but we failed to find a run-queue

Why not introduce in push_dl_task() as well?