linux-kernel - [PATCH 0/1] kthread: don't abuse kthread_create_on_cpu() in __kthread_create

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Date:   Thu, 10 Nov 2016 18:19:58 +0100
From:   Oleg Nesterov <oleg@...hat.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Petr Mladek <pmladek@...e.com>
Cc:     Andy Lutomirski <luto@...capital.net>,
        Roman Pen <roman.penyaev@...fitbricks.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, Tejun Heo <tj@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Chunming Zhou <David1.Zhou@....com>,
        Alex Deucher <alexander.deucher@....com>
Subject: [PATCH 0/1] kthread: don't abuse kthread_create_on_cpu() in
 __kthread_create_worker()

On 11/09, Oleg Nesterov wrote:
>
> Yes, agreed. Again, I'll write another email. Perhaps we should even keep
> park/unpark exported and change them to avoid the races with exit/itself,
> I dunno.
>
> My real point was, imo the KTHREAD_IS_PER_CPU/__kthread_bind(kthread->cpu)
> logic in kthread_unpark() should be private to smpboot.c/cpu.c.
>
> I'll send another patch tomorrow. kthread_create_worker_on_cpu() ab-uses
> this logic too for no reason, but this is trivial.

After this change we are almost ready to kill kthread->cpu and KTHREAD_IS_PER_CPU.
(but the change itself doesn't depend on the previous patches).

Petr, why do we need kthread_create_worker_on_cpu() ? It has no users and
I can not imagine any "real" use-case for it. Perhaps it can be removed?

Oleg.