Crash from :i915 module with 4.15.0-46-generic using multi-display

[Nicolas Devillers]

=== SRU Justification ===
[Impact]
4.15.0-46 breaks once working external display over docking.

[Fix]
Revert the commit that causes regression.

[Test]
User confirms reverting the commit solves the regression.

[Regression Potential]
Low. Docking can works without this commit on Bionic kernel.

While previously working using 4.15.0-45-generic, booting my thinkpad T480 on a dock with additional screen connected and "kernel 4.15.0-46-generic" lead to a crash of the system.

=== Original Bug Report ===

Laptop is running Ubuntu 18.04.2 LTS.
---
ProblemType: Bug
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/pcmC1D0c: user 3449 F...m pulseaudio
 /dev/snd/controlC1: user 3449 F.... pulseaudio
 /dev/snd/pcmC0D0p: user 3449 F...m pulseaudio
 /dev/snd/controlC0: user 3449 F.... pulseaudio
CurrentDesktop: X-Cinnamon
DistroRelease: Ubuntu 18.04
HibernationDevice: RESUME=UUID=c94c8e19-c9cc-49db-b6e7-4e1542a5efa7
InstallationDate: Installed on 2018-06-28 (256 days ago)
InstallationMedia: Ubuntu-Budgie 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
MachineType: LENOVO 20L5000AFR
Package: linux (not installed)
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.15.0-45-generic root=/dev/mapper/ubuntu--budgie--vg-root ro quiet splash
ProcVersionSignature: Ubuntu 4.15.0-45.48-generic 4.15.18
RelatedPackageVersions:
 linux-restricted-modules-4.15.0-45-generic N/A
 linux-backports-modules-4.15.0-45-generic N/A
 linux-firmware 1.173.3
Tags: bionic
Uname: Linux 4.15.0-45-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip docker libvirt lpadmin netdev plugdev sambashare sudo vboxusers wireshark
_MarkForUpload: True
dmi.bios.date: 03/14/2018
dmi.bios.vendor: LENOVO
dmi.bios.version: N24ET37W (1.12 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20L5000AFR
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40697 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.modalias: dmi:bvnLENOVO:bvrN24ET37W(1.12):bd03/14/2018:svnLENOVO:pn20L5000AFR:pvrThinkPadT480:rvnLENOVO:rn20L5000AFR:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone:
dmi.product.family: ThinkPad T480
dmi.product.name: 20L5000AFR
dmi.product.version: ThinkPad T480
dmi.sys.vendor: LENOVO

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1819486

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Nicolas Devillers (nicolas-devillers)]

apport information

[Nicolas Devillers (nicolas-devillers)]

apport information

[Nicolas Devillers (nicolas-devillers)]

apport information

[Nicolas Devillers (nicolas-devillers)]

apport information

[Nicolas Devillers (nicolas-devillers)]

apport information

[Nicolas Devillers (nicolas-devillers)]

apport information

[Nicolas Devillers (nicolas-devillers)]

apport information

[Nicolas Devillers (nicolas-devillers)]

apport information

[Nicolas Devillers (nicolas-devillers)]

apport information

[Nicolas Devillers (nicolas-devillers)]

apport information

[Nicolas Devillers (nicolas-devillers)]

apport information

[Nicolas Devillers (nicolas-devillers)]

apport information

[Nicolas Devillers (nicolas-devillers)]

apport information

[Nicolas Devillers (nicolas-devillers)]

apport information

[Nicolas Devillers (nicolas-devillers)]

apport information

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Kai-Heng Feng (kaihengfeng)]

Please test this kernel:
https://people.canonical.com/~khfeng/lp1819486/

[Nicolas Devillers (nicolas-devillers)]

Kai, It looks like that the intel driver was not bundle in this kernel? No kernel panic but WM runs in software mode and additional display are not being detected.

[Kai-Heng Feng (kaihengfeng)]

*modules* not installed?

[Nicolas Devillers (nicolas-devillers)]

pff, clearly I needed one cup of coffee before answering this.. sry. I will check again shortly..

[Nicolas Devillers (nicolas-devillers)]

Yeah, it works fine with your module. Did you just revert "drm-i915-fix-hotplug-irq-ack-on-i965-g4x.patch" ?

[Kai-Heng Feng (kaihengfeng)]

Yes, that's the only commit between -45 and -46.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-bionic' to 'verification-done-bionic'. If the problem still exists, change the tag 'verification-needed-bionic' to 'verification-failed-bionic'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Kleber Sacilotto de Souza (kleber-souza)]

Hello Nicolas,

Could you please verify if the Bionic kernel currently in -proposed fixed the issue as expected?

Thank you.

[Nicolas Devillers (nicolas-devillers)]

Hello,

It works fine with the proposed kernel 4.15.0-48-generic taken at:

http://ppa.launchpad.net/canonical-kernel-team/proposed/ubuntu/pool/main/l/linux/

Please note that I updated to the latest Lenovo Provided Bios (1.23) since then.

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.15.0-48.51

---------------
linux (4.15.0-48.51) bionic; urgency=medium

  * linux: 4.15.0-48.51 -proposed tracker (LP: #1822820)

  * Packaging resync (LP: #1786013)
    - [Packaging] update helper scripts
    - [Packaging] resync retpoline extraction

  * 3b080b2564287be91605bfd1d5ee985696e61d3c in ubuntu_btrfs_kernel_fixes
    triggers system hang on i386 (LP: #1812845)
    - btrfs: raid56: properly unmap parity page in finish_parity_scrub()

  * [P9][LTCTest][Opal][FW910] cpupower monitor shows multiple stop Idle_Stats
    (LP: #1719545)
    - cpupower : Fix header name to read idle state name

  * [amdgpu] screen corruption when using touchpad (LP: #1818617)
    - drm/amdgpu/gmc: steal the appropriate amount of vram for fw hand-over (v3)
    - drm/amdgpu: Free VGA stolen memory as soon as possible.

  * [SRU][B/C/OEM]IOMMU: add kernel dma protection (LP: #1820153)
    - ACPICA: AML parser: attempt to continue loading table after error
    - ACPI / property: Allow multiple property compatible _DSD entries
    - PCI / ACPI: Identify untrusted PCI devices
    - iommu/vt-d: Force IOMMU on for platform opt in hint
    - iommu/vt-d: Do not enable ATS for untrusted devices
    - thunderbolt: Export IOMMU based DMA protection support to userspace
    - iommu/vt-d: Disable ATS support on untrusted devices

  * Add basic support to NVLink2 passthrough (LP: #1819989)
    - powerpc/powernv/npu: Do not try invalidating 32bit table when 64bit table is
      enabled
    - powerpc/powernv: call OPAL_QUIESCE before OPAL_SIGNAL_SYSTEM_RESET
    - powerpc/powernv: Export opal_check_token symbol
    - powerpc/powernv: Make possible for user to force a full ipl cec reboot
    - powerpc/powernv/idoa: Remove unnecessary pcidev from pci_dn
    - powerpc/powernv: Move npu struct from pnv_phb to pci_controller
    - powerpc/powernv/npu: Move OPAL calls away from context manipulation
    - powerpc/pseries/iommu: Use memory@ nodes in max RAM address calculation
    - powerpc/pseries/npu: Enable platform support
    - powerpc/pseries: Remove IOMMU API support for non-LPAR systems
    - powerpc/powernv/npu: Check mmio_atsd array bounds when populating
    - powerpc/powernv/npu: Fault user page into the hypervisor's pagetable

  * Huawei Hi1822 NIC has poor performance (LP: #1820187)
    - net-next: hinic: fix a problem in free_tx_poll()
    - hinic: remove ndo_poll_controller
    - net-next/hinic: add checksum offload and TSO support
    - hinic: Fix l4_type parameter in hinic_task_set_tunnel_l4
    - net-next/hinic:replace multiply and division operators
    - net-next/hinic:add rx checksum offload for HiNIC
    - net-next/hinic:fix a bug in set mac address
    - net-next/hinic: fix a bug in rx data flow
    - net: hinic: fix null pointer dereference on pointer hwdev
    - hinic: optmize rx refill buffer mechanism
    - net-next/hinic:add shutdown callback
    - net-next/hinic: replace disable_irq_nosync/enable_irq

  * [CONFIG] please enable highdpi font FONT_TER16x32 (LP: #1819881)
    - Fonts: New Terminus large console font
    - [Config]: enable highdpi Terminus 16x32 font support

  * [19.04 FEAT] qeth: Enhanced link...

[Nicolas Devillers (nicolas-devillers)]

Hi,

This bug was present and fixed by reverting the i915 patch. I don't understand why it status would be changed to invalid.