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

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Message-ID: <2025070408-starlight-pandemic-0266@gregkh>
Date: Fri, 4 Jul 2025 15:44:49 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: David Jeffery <djeffery@...hat.com>
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 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.

thanks,

greg k-h