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Sender: Guenter Roeck <groeck7@gmail.com>
Date:   Fri, 19 Aug 2022 13:55:18 -0700
From:   Guenter Roeck <linux@roeck-us.net>
To:     Bart Van Assche <bvanassche@acm.org>
Cc:     Isaac Manjarres <isaacmanjarres@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Tomeu Vizoso <tomeu.vizoso@collabora.com>,
        Russell King <rmk+kernel@arm.linux.org.uk>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Saravana Kannan <saravanak@google.com>, stable@kernel.org,
        kernel-team@android.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] driver core: Fix bus_type.match() error handling
Message-ID: <20220819205518.GA3151965@roeck-us.net>
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On Fri, Aug 19, 2022 at 01:01:29PM -0700, Bart Van Assche wrote:
> On 8/19/22 10:45, Isaac Manjarres wrote:
> > It seems that the patches mentioned in [1] are causing a hang during
> > reboot for various ARM emulations when booting from USB. Can you please
> > take a look? There's more information about what defconfig, rootfs, and
> > qemu commandline to use at [2].
> 
> Unfortunately I can't reproduce this hang in an x86 VM with kernel v6.0-rc1
> and a USB disk attached via virt-manager. The lsscsi -v output shows that a
> USB disk has been attached:
> 

The problem only reproduces with various arm emulations. I may have missed it,
but I have not noticed it on any other architecture.

> [9:0:0:0]    disk    QEMU     QEMU HARDDISK    2.5+  /dev/sdd
>   dir: /sys/bus/scsi/devices/9:0:0:0 [/sys/devices/pci0000:00/0000:00:07.0/usb2/2-2/2-2:1.0/host9/target9:0:0/9:0:0:0]
> 
> Rebooting that VM happens in the expected time and without triggering any
> kernel warnings.
> 
There are no warnings. The reboot just stalls. Also, the usb drive
attaches just fine. The probem is seen in shutdown, not during boot.

> Since the issue has been observed in qemu, how about sharing the sysrq-t
> output? I recommend to collect that output as follows:
> * Send the serial console output to a file. This involves adding
> console=ttyS0,115200n8 to the kernel command line and using the proper qemu
> options to save the serial console output into a file.
> * Reproduce the hang and send the sysrq-t key sequence to qemu, e.g. as
> follows: virsh send-key ${vm_name} KEY_LEFTALT KEY_SYSRQ KEY_T
> 

Will try.

Thanks,
Guenter