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From: Thomas Gleixner <tglx@linutronix.de>
To: Andy Lutomirski <luto@kernel.org>, Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [patch 4/5] sched: Delay task stack freeing on RT
Date: Fri, 01 Oct 2021 22:54:08 +0200	[thread overview]
Message-ID: <87a6js4gb3.ffs@tglx> (raw)
In-Reply-To: <CALCETrXk0i50vyWwou0AT0jtb7V2pqZiJW_7_dqrthi1N19qeg@mail.gmail.com>

On Fri, Oct 01 2021 at 12:02, Andy Lutomirski wrote:
> On Fri, Oct 1, 2021 at 11:48 AM Andy Lutomirski <luto@kernel.org> wrote:
>>
>> On Fri, Oct 1, 2021 at 10:24 AM Thomas Gleixner <tglx@linutronix.de> wrote:
>> >
>
>> ISTM it would be conceptually for do_exit() to handle its own freeing
>> in its own preemptible context.  Obviously that can't really work,
>> since we can't free a task_struct or a task stack while we're running
>> on it.  But I wonder if we could approximate it by putting this work
>> in a workqueue so that it all runs in a normal schedulable context.
>> To make the shell script case work nicely, we want to release the task
>> stack before notifying anyone waiting for the dying task to exit, but
>> maybe that's doable.  It could involve some nasty exit_signal hackery,
>> though.
>
> I'm making this way more complicated than it needs to be.  How about
> we unaccount the task stack in do_exit and release it for real in
> finish_task_switch()?  Other than accounting, free_thread_stack
> doesn't take any locks.

Right.


  reply	other threads:[~2021-10-01 20:54 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-28 12:24 [patch 0/5] sched: Miscellaneous RT related tweaks Thomas Gleixner
2021-09-28 12:24 ` [patch 1/5] sched: Limit the number of task migrations per batch on RT Thomas Gleixner
2021-10-01 15:05   ` [tip: sched/core] " tip-bot2 for Thomas Gleixner
2021-10-05 14:11   ` tip-bot2 for Thomas Gleixner
2021-09-28 12:24 ` [patch 2/5] sched: Disable TTWU_QUEUE " Thomas Gleixner
2021-10-01 15:05   ` [tip: sched/core] " tip-bot2 for Thomas Gleixner
2021-10-05 14:11   ` tip-bot2 for Thomas Gleixner
2021-09-28 12:24 ` [patch 3/5] sched: Move kprobes cleanup out of finish_task_switch() Thomas Gleixner
2021-10-01 15:05   ` [tip: sched/core] " tip-bot2 for Thomas Gleixner
2021-10-05 14:11   ` tip-bot2 for Thomas Gleixner
2021-09-28 12:24 ` [patch 4/5] sched: Delay task stack freeing on RT Thomas Gleixner
2021-09-29 11:54   ` Peter Zijlstra
2021-10-01 16:12     ` Andy Lutomirski
2021-10-01 17:24       ` Thomas Gleixner
2021-10-01 18:48         ` Andy Lutomirski
2021-10-01 19:02           ` Andy Lutomirski
2021-10-01 20:54             ` Thomas Gleixner [this message]
2021-09-28 12:24 ` [patch 5/5] sched: Move mmdrop to RCU " Thomas Gleixner
2021-09-29 12:02   ` Peter Zijlstra
2021-09-29 13:05     ` Thomas Gleixner
2021-10-01 15:05   ` [tip: sched/core] " tip-bot2 for Thomas Gleixner
2021-10-05 14:11   ` tip-bot2 for Thomas Gleixner

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