linux-kernel - Re: [PATCH v10 0/5] shut down devices asynchronously

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Message-ID: <CA+-xHTFKh0VUJ0r4K5L5b0dmrs9d1+cNkqf4HvKa4E-r_+u2CA@mail.gmail.com>
Date: Fri, 4 Jul 2025 10:09:01 -0400
From: David Jeffery <djeffery@...hat.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Christoph Hellwig <hch@....de>, Stuart Hayes <stuart.w.hayes@...il.com>, linux-kernel@...r.kernel.org, 
	"Rafael J . Wysocki" <rafael@...nel.org>, Martin Belanger <Martin.Belanger@...l.com>, 
	"Oliver O'Halloran" <oohall@...il.com>, Daniel Wagner <dwagner@...e.de>, Keith Busch <kbusch@...nel.org>, 
	Lukas Wunner <lukas@...ner.de>, Jeremy Allison <jallison@....com>, Jens Axboe <axboe@...com>, 
	Sagi Grimberg <sagi@...mberg.me>, linux-nvme@...ts.infradead.org, 
	Nathan Chancellor <nathan@...nel.org>, Jan Kiszka <jan.kiszka@...mens.com>, 
	Bert Karwatzki <spasswolf@....de>
Subject: Re: [PATCH v10 0/5] shut down devices asynchronously

On Fri, Jul 4, 2025 at 9:45 AM Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> On Fri, Jul 04, 2025 at 09:38:15AM -0400, David Jeffery wrote:
> > On Thu, Jul 3, 2025 at 7:47 AM Christoph Hellwig <hch@....de> wrote:
> > >
> > > On Wed, Jun 25, 2025 at 03:18:48PM -0500, Stuart Hayes wrote:
> > > > Address resource and timing issues when spawning a unique async thread
> > > > for every device during shutdown:
> > > >   * Make the asynchronous threads able to shut down multiple devices,
> > > >     instead of spawning a unique thread for every device.
> > > >   * Modify core kernel async code with a custom wake function so it
> > > >     doesn't wake up threads waiting to synchronize every time the cookie
> > > >     changes
> > >
> > > Given all these thread spawning issues, why can't we just go back
> > > to the approach that kicks off shutdown asynchronously and then waits
> > > for it without spawning all these threads?
> > >
> >
> > The async subsystem fix is something that should be fixed regardless
> > of async shutdown. Async shutdown's use just exposed its thundering
> > herd behavior which is easily fixed.
>
> Great, then please submit that on its own and get the maintainer of that
> subsystem to agree and accept it as I have no way to judge that code at
> all.

Unfortunately, it does not have a maintainer listed and sees limited
activity. Would CC-ing some of the recent developers of kernel/async.c
to ask them to review be recommended in this situation?

David Jeffery