Date:	Tue, 15 Jul 2014 18:51:19 -0700
From:	Markus Gutschke <markus@...schke.com>
To:	linux-kernel@...r.kernel.org
Subject: 3.16-rcX crashes on resume from Suspend-To-RAM

My Dell M4400 has been pretty well-supported by Linux a couple of
years now, but recent 3.16-rcX cause hard crashes when resuming from
Suspend-to-RAM.

This is tricky to debug, as device drivers are not yet restored by the
time that the crash happens. So, I can't use Page-UP to scroll the
screen and see the full crash information. I also cannot use the
netconsole; the ethernet device is still suspended. For similar
reasons, crash kernels don't seem to work either.

After about a day of false starts and a lengthy bi-secting session, I
finally narrowed things down to this change list:

eec15edbb0e14485998635ea7c62e30911b465f0 is the first bad commit
commit eec15edbb0e14485998635ea7c62e30911b465f0
Author: Zhang Rui <rui.zhang@...el.com>
Date:   Fri May 30 04:23:01 2014 +0200

    ACPI / PNP: use device ID list for PNPACPI device enumeration

    ACPI can be used to enumerate PNP devices, but the code does not
    handle this in the right way currently.  Namely, if an ACPI device
    object
     1. Has a _CRS method,
     2. Has an identification of
        "three capital characters followed by four hex digits",
     3. Is not in the excluded IDs list,
    it will be enumerated to PNP bus (that is, a PNP device object will
    be create for it).  This means that, actually, the PNP bus type is
    used as the default bus type for enumerating _HID devices in ACPI.

    However, more and more _HID devices need to be enumerated to the
    platform bus instead (that is, platform device objects need to be
    created for them).  As a result, the device ID list in acpi_platform.c
    is used to enforce creating platform device objects rather than PNP
    device objects for matching devices.  That list has been continuously
    growing recently, unfortunately, and it is pretty much guaranteed to
    grow even more in the future.

    To address that problem it is better to enumerate _HID devices
    as platform devices by default.  To this end, change the way of
    enumerating PNP devices by adding a PNP ACPI scan handler that
    will use a device ID list to create PNP devices for the ACPI
    device objects whose device IDs are present in that list.

    The initial device ID list in the PNP ACPI scan handler contains
    all of the pnp_device_id strings from all the existing PNP drivers,
    so this change should be transparent to the PNP core and all of the
    PNP drivers.  Still, in the future it should be possible to reduce
    its size by converting PNP drivers that need not be PNP for any
    technical reasons into platform drivers.

    Signed-off-by: Zhang Rui <rui.zhang@...el.com>
    [rjw: Rewrote the changelog, modified the PNP ACPI scan handler code]
    Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
    Reviewed-by: Mika Westerberg <mika.westerberg@...ux.intel.com>

:040000 040000 b7c07232aa46ae7b6faf9a907fb7274a02e4680fc2e05b31a61dccd087c554adecc89a43a1ed81f7
M drivers
:040000 040000 4eda970292fffbeebe167f9210502527df4e8ab421e9e6fd84c780a34bf3d48b5e7618b551da3b1a
M include

I took a photo of the crash. It feels silly to do, but I couldn't
think of a better solution. You can find it at
https://drive.google.com/file/d/0B8SxqKDe4hyheTlTLXY2YThkMXM

As I mentioned earlier, a bunch of information has already scrolled
off the screen, but hopefully what is visible is somewhat helpful.

I will have only limited internet access the next couple of weeks. But
I wanted to make sure I at least got the result of the bisection out
to LKML. I will make every best effort to collect additional data, if
asked to do so; but some of it might be delayed for a little bit,
until I can get access to reasonably powerful hardware or reasonably
fast internet.


Markus

P.S.: Please keep me cc'd on all responses, as I am not subscribed to
the firehose that is LKML.
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