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Date:   Fri, 19 Aug 2022 13:01:29 -0700
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Subject: Re: [PATCH v2] driver core: Fix bus_type.match() error handling
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To:     Isaac Manjarres <isaacmanjarres@google.com>,
        Guenter Roeck <linux@roeck-us.net>
Cc:     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
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From:   Bart Van Assche <bvanassche@acm.org>
In-Reply-To: <Yv/MKymRC9O04Nqu@google.com>
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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:

[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.

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

Thanks,

Bart.