linux-kernel - Re: [PATCH 1/1] io_uring/sqpoll: inherit cpumask of creating process

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Message-ID: <ed995e2d-23b7-44c5-b064-2927dc20420f@kernel.dk>
Date: Fri, 6 Sep 2024 10:00:46 -0600
From: Jens Axboe <axboe@...nel.dk>
To: Felix Moessbauer <felix.moessbauer@...mens.com>, asml.silence@...il.com
Cc: linux-kernel@...r.kernel.org, io-uring@...r.kernel.org,
 cgroups@...r.kernel.org, dqminh@...udflare.com, longman@...hat.com,
 adriaan.schmidt@...mens.com, florian.bezdeka@...mens.com,
 stable@...r.kernel.org
Subject: Re: [PATCH 1/1] io_uring/sqpoll: inherit cpumask of creating process

On 9/6/24 7:44 AM, Felix Moessbauer wrote:
> diff --git a/io_uring/sqpoll.c b/io_uring/sqpoll.c
> index 3b50dc9586d1..4681b2c41a96 100644
> --- a/io_uring/sqpoll.c
> +++ b/io_uring/sqpoll.c
> @@ -289,7 +289,7 @@ static int io_sq_thread(void *data)
>  	if (sqd->sq_cpu != -1) {
>  		set_cpus_allowed_ptr(current, cpumask_of(sqd->sq_cpu));
>  	} else {
> -		set_cpus_allowed_ptr(current, cpu_online_mask);
> +		set_cpus_allowed_ptr(current, sqd->thread->cpus_ptr);
>  		sqd->sq_cpu = raw_smp_processor_id();
>  	}

On second thought, why are we even setting this in the first place?
sqd->thread == current here, it should be a no-op to do:

	set_cpus_allowed_ptr(current, current->cpus_ptr);

IOW, the line should just get deleted. Can you send out a v2?

-- 
Jens Axboe