> Does the Samsung 840 EVO SSD support UAS (USB attached SCSI?) i.e. does
> it use the uas driver instead of mass-storage?

I don't think UAS is an issue here: I tried disabling it for the SSD
using a quirk (ie with the line "options usb_storage
quirks=174c:1053:u" in the file /etc/modprobe.d/usb_storage.conf) and
the kernel still locked up.

> Could you take full logs from boot with xhci debugging and tracing both 
> enabled?

See attached. The SSD is /dev/sda and /media/cat is where it tries to
mount /dev/sda1, and there's a NULL dereference at 32.736157 that
might be the cause of the lockup.



On Tue, Jun 20, 2017 at 6:17 PM, Mathias Nyman
<mathias.ny...@linux.intel.com> wrote:
> On 20.06.2017 12:47, rocko r wrote:
>>
>> Whenever I boot my laptop and log into the desktop with a USB-C to
>> USB-3 hub attached and a Samsung 840 EVO SSD attached to the USB-C
>> hub, the laptop locks up completely for kernel versions 4.12-rc1
>> through 4.12-rc6. Kernels 4.10 and 4.11 do not crash, so this is a
>> regression.
>>
>> The lock-up occurs shortly after logging into the desktop. Note that
>> when I am presented with the lightdm login screen, my mouse attached
>> via the USB-C to USB-3 hub works, but it stops working after the
>> desktop first appears, as if the USB-C hub has gone offline, and then
>> it starts working again maybe five to ten seconds later (this also
>> happens in kernel 4.11, but 4.11 successfully mounts the SSD and does
>> not lock up).
>>
>> Shortly after this in kernels 4.12-rcX, the SSD fails to mount and at
>> some point after this, syslog shows soft lockup errors. Eventually the
>> entire laptop locks up and has to be hard-reset. When I tried 4.12-rc6
>> today, the laptop locked up almost immediately and did not store a
>> message in syslog.
>>
>> This bug happens every time when rebooting and then logging into the
>> desktop with that particular configuration, ie SSD attached via the
>> USB-C to USB-3 hub. If I have the USB-C to USB-3 hub attached and the
>> SSD attached via one of the laptop's USB-3 ports, the laptop does not
>> lock up. If I plug in the SSD to the USB-C hub after booting into the
>> desktop, the laptop does not lock up.
>>
>> Attached is a log of the soft lockup BUG message from 4.12-rc5 and
>> also another NULL dereference error I noticed today that might be
>> related.
>>
>
> The type-c port is controller by a separate hotpluggable PCI xHCI
> controller,
>
> Looks like that controller disappears for a while, and driver tries to cope
> with it but hangs while freeing streams.
>
> Does the Samsung 840 EVO SSD support UAS (USB attached SCSI?) i.e. does
> it use the uas driver instead of mass-storage?
>
> Could you take full logs from boot with xhci debugging and tracing both
> enabled?
>
> add xhci_hcd.dyndbg=+p  or  module xhci_hcd +p to kernel cmdline  for xhci
> debugging,
> and trace_event=xhci-hcd  trace_buf_size=10M   for tracing
>
> Thanks
> Mathias
>

Attachment: xhcd and events.log.xz
Description: application/xz

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