linux-kernel - Re: [PATCH v8 3/4] driver core: shut down devices asynchronously

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Message-ID: <20240905221340.GA2732347@thelio-3990X>
Date: Thu, 5 Sep 2024 15:13:40 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Stuart Hayes <stuart.w.hayes@...il.com>
Cc: linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.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>, David Jeffery <djeffery@...hat.com>,
	Jeremy Allison <jallison@....com>, Jens Axboe <axboe@...com>,
	Christoph Hellwig <hch@....de>, Sagi Grimberg <sagi@...mberg.me>,
	linux-nvme@...ts.infradead.org
Subject: Re: [PATCH v8 3/4] driver core: shut down devices asynchronously

Hi Stuart,

On Thu, Aug 22, 2024 at 03:28:04PM -0500, Stuart Hayes wrote:
> Add code to allow asynchronous shutdown of devices, ensuring that each
> device is shut down before its parents & suppliers.
> 
> Only devices with drivers that have async_shutdown_enable enabled will be
> shut down asynchronously.
> 
> This can dramatically reduce system shutdown/reboot time on systems that
> have multiple devices that take many seconds to shut down (like certain
> NVMe drives). On one system tested, the shutdown time went from 11 minutes
> without this patch to 55 seconds with the patch.
> 
> Signed-off-by: Stuart Hayes <stuart.w.hayes@...il.com>
> Signed-off-by: David Jeffery <djeffery@...hat.com>

I am noticing several QEMU machines hang while shutting down after this
change as commit 8064952c6504 ("driver core: shut down devices
asynchronously") in -next. An easy test case due to the size of the
configuration:

  $ make -skj"$(nproc)" ARCH=arm64 CROSS_COMPILE=aarch64-linux- mrproper virtconfig Image.gz

  $ curl -LSs https://github.com/ClangBuiltLinux/boot-utils/releases/download/20230707-182910/arm64-rootfs.cpio.zst | zstd -d >rootfs.cpio

  $ timeout --foreground 3m \
    qemu-system-aarch64 \
      -display none \
      -nodefaults \
      -cpu max,pauth-impdef=true \
      -machine virt,gic-version=max,virtualization=true \
      -append 'console=ttyAMA0 earlycon' \
      -kernel arch/arm64/boot/Image.gz \
      -initrd rootfs.cpio \
      -m 512m \
      -serial mon:stdio
  [    0.000000] Linux version 6.11.0-rc4-00022-g8064952c6504 (nathan@...lio-3990X) (aarch64-linux-gcc (GCC) 14.2.0, GNU ld (GNU Binutils) 2.42) #1 SMP PREEMPT Thu Sep  5 15:02:42 MST 2024
  ...
  The system is going down NOW!
  Sent SIGTERM to all processes
  Sent SIGKILL to all processes
  Requesting system poweroff
  qemu-system-aarch64: terminating on signal 15 from pid 2753792 (timeout)

At the parent commit, there are the following two prints after
"Requesting system poweroff" then the machine properly shuts down:

  [    3.411387] kvm: exiting hardware virtualization
  [    3.411741] reboot: Power down

If there is any other information I can provide or patches that I can
test, I am more than happy to do so.

Cheers,
Nathan