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

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Message-ID: <d4d3ef1f-3f34-40c5-88d5-ed1f35123705@gmail.com>
Date: Fri, 6 Sep 2024 09:44:50 -0500
From: stuart hayes <stuart.w.hayes@...il.com>
To: Nathan Chancellor <nathan@...nel.org>
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



On 9/5/2024 5:13 PM, Nathan Chancellor wrote:
> 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


Thanks, I'll take a look.