linux-kernel - Re: [PATCH v2 0/8] kernel/fork: Move thread stack free otu of the scheduler path.

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Message-ID: <6ac2e2c8-798a-2b52-43f4-a4d940b39e2d@kernel.org>
Date:   Mon, 21 Feb 2022 10:44:06 -0800
From:   Andy Lutomirski <luto@...nel.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        linux-kernel@...r.kernel.org, linux-ia64@...r.kernel.org
Cc:     Ben Segall <bsegall@...gle.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vincent Guittot <vincent.guittot@...aro.org>
Subject: Re: [PATCH v2 0/8] kernel/fork: Move thread stack free otu of the
 scheduler path.

On 2/17/22 02:23, Sebastian Andrzej Siewior wrote:
> This is a follup-up on the patch
>      sched: Delay task stack freeing on RT
>      https://lkml.kernel.org/r/20210928122411.593486363@linutronix.de
> 
> It addresses the review feedback:
> - Decouple stack accounting from its free invocation. The accounting
>    happens in do_exit(), the final free call happens later.
> 
> - Add put_task_stack_sched() to finish_task_switch(). Here the VMAP
>    stack is cached only. If it fails, or in the !VMAP case then the final
>    free happens in delayed_put_task_struct(). This is also an oportunity
>    to cache the stack.
> 
> Changes since v1:
>    - Drop the bit marked und use addtional RCU head to free the stack in
>    case that it can't be cached. Suggested by Andy Lutomirski.

Acked-by: Andy Lutomirski <luto@...nel.org>

This version is much nicer.  Thanks!

--Andy