linux-kernel - Re: [PATCH] kthread: Use TASK_IDLE state for newly created kernel threads

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Date:   Wed, 20 May 2020 20:18:58 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Pavankumar Kondeti <pkondeti@...eaurora.org>
Cc:     linux-kernel@...r.kernel.org,
        Vinayak Menon <vinmenon@...eaurora.org>,
        Ben Dooks <ben.dooks@...ethink.co.uk>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>,
        Liang Chen <cl@...k-chips.com>
Subject: Re: [PATCH] kthread: Use TASK_IDLE state for newly created kernel
 threads

On Wed, May 20, 2020 at 05:25:09PM +0530, Pavankumar Kondeti wrote:
> When kernel threads are created for later use, they will be in
> TASK_UNINTERRUPTIBLE state until they are woken up. This results
> in increased loadavg and false hung task reports. To fix this,
> use TASK_IDLE state instead of TASK_UNINTERRUPTIBLE when
> a kernel thread schedules out for the first time.
> 
> Signed-off-by: Pavankumar Kondeti <pkondeti@...eaurora.org>
> ---
>  kernel/kthread.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/kthread.c b/kernel/kthread.c
> index bfbfa48..b74ed8e 100644
> --- a/kernel/kthread.c
> +++ b/kernel/kthread.c
> @@ -250,7 +250,7 @@ static int kthread(void *_create)
>  	current->vfork_done = &self->exited;
>  
>  	/* OK, tell user we're spawned, wait for stop or wakeup */
> -	__set_current_state(TASK_UNINTERRUPTIBLE);
> +	__set_current_state(TASK_IDLE);
>  	create->result = current;
>  	/*
>  	 * Thread is going to call schedule(), do not preempt it,
> @@ -428,7 +428,7 @@ static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state)
>  
>  void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask)
>  {
> -	__kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE);
> +	__kthread_bind_mask(p, mask, TASK_IDLE);
>  }
>  
>  /**
> @@ -442,7 +442,7 @@ void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask)
>   */
>  void kthread_bind(struct task_struct *p, unsigned int cpu)
>  {
> -	__kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE);
> +	__kthread_bind(p, cpu, TASK_IDLE);
>  }
>  EXPORT_SYMBOL(kthread_bind);

It's as if people never read mailing lists:
	https://lore.kernel.org/r/DM6PR11MB3531D3B164357B2DC476102DDFC90@DM6PR11MB3531.namprd11.prod.outlook.com

Given that this is an identical resend of the previous patch, why are
you doing so, and what has changed since that original rejection?

greg k-h