bionic snapdragon 4.15 snap failed Certification testing

[Kelsey Steele]

[SRU Justification]

[Impact]

snap certification testing failed with bionic/linux-snapdragon

https://bugs.launchpad.net/bugs/1874763

After investigations by Kleber, failure was found to be from a drm driver which is compiled when CONFIG_DRM_MSM is set.

Information reported from Paul Larson [1]:

We have a cold reboot test in checkbox that seems to be failing with this kernel. The test runs the following commands to try to trigger a cold reboot:
 rtcwake --mode no -s 120
 sleep 5
 rtcwake -m show
 sleep 5
 dbus-send --system --print-reply --dest=org.freedesktop.login1 /org/freedesktop/login1 "org.freedesktop.login1.Manager.PowerOff" boolean:true

However, the system never fully reboots. On the serial console, I just see:
...
Press enter to configure.
[ 137.402465] systemd-shutdown[1]: Failed to wait for process: Protocol error
[ 137.406163] systemd-shutdown[1]: Failed to wait for process: Protocol error

I do have the ability to remotely remove power from the device and restore it, however after doing that, I get an oops on the serial console and the system never comes up.

[1] https://bugs.launchpad.net/kernel-sru-workflow/+bug/1874763/comments/1

[Test]
Run Certification Testing

The tests are ran only with UC18, so a kernel snap is needed to either build a new image or promote it to edge.

[Fix]

The affected drm driver is set by CONFIG_DRM_MSM which is also set on bionic/linux

Revert upstream commits on Bionic/linux:

0519bad6f34f drm/msm: Use the correct dma_sync calls in msm_gem
7318c5ef642b drm/msm: stop abusing dma_map/unmap for cache

[Risk of Regression]

Alternative solutions would need to be found for dma_sync calls in msm_gem and to avoid abusing dma_map/unmap for cache. The commits both came from upstream stable.

[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)]

Certification tests of bionic/snapdragon-kernel snap completed successfully: bug 1877979. Marking verification as done.

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.15.0-101.102

---------------
linux (4.15.0-101.102) bionic; urgency=medium

  * bionic/linux: 4.15.0-101.102 -proposed tracker (LP: #1877262)

  * 4.15.0-100.101 breaks userspace builds due to a bug in the headers
    /usr/include/linux/swab.h of linux-libc-dev (LP: #1877123)
    - include/uapi/linux/swab.h: fix userspace breakage, use __BITS_PER_LONG for
      swap

  * bionic snapdragon 4.15 snap failed Certification testing (LP: #1877657)
    - Revert "drm/msm: Use the correct dma_sync calls in msm_gem"
    - Revert "drm/msm: stop abusing dma_map/unmap for cache"

linux (4.15.0-100.101) bionic; urgency=medium

  * bionic/linux: 4.15.0-100.101 -proposed tracker (LP: #1875878)

  * built-using constraints preventing uploads (LP: #1875601)
    - temporarily drop Built-Using data

  * Add debian/rules targets to compile/run kernel selftests (LP: #1874286)
    - [Packaging] add support to compile/run selftests

  * getitimer returns it_value=0 erroneously (LP: #1349028)
    - [Config] CONTEXT_TRACKING_FORCE policy should be unset

  * QEMU/KVM display is garbled when booting from kernel EFI stub due to missing
    bochs-drm module (LP: #1872863)
    - [Config] Enable CONFIG_DRM_BOCHS as module for all archs

  * Backport MPLS patches from 5.3 to 4.15 (LP: #1851446)
    - net/mlx5e: Report netdevice MPLS features
    - net: vlan: Inherit MPLS features from parent device
    - net: bonding: Inherit MPLS features from slave devices
    - net/mlx5e: Move to HW checksumming advertising

  * LIO hanging in iscsit_free_session and iscsit_stop_session (LP: #1871688)
    - scsi: target: remove boilerplate code
    - scsi: target: fix hang when multiple threads try to destroy the same iscsi
      session
    - scsi: target: iscsi: calling iscsit_stop_session() inside
      iscsit_close_session() has no effect

  * Add hw timestamps to received skbs in peak_canfd (LP: #1874124)
    - can: peak_canfd: provide hw timestamps in rx skbs

  * Bionic update: upstream stable patchset 2020-04-23 (LP: #1874502)
    - ARM: dts: sun8i-a83t-tbs-a711: HM5065 doesn't like such a high voltage
    - bus: sunxi-rsb: Return correct data when mixing 16-bit and 8-bit reads
    - net: vxge: fix wrong __VA_ARGS__ usage
    - hinic: fix a bug of waitting for IO stopped
    - hinic: fix wrong para of wait_for_completion_timeout
    - cxgb4/ptp: pass the sign of offset delta in FW CMD
    - qlcnic: Fix bad kzalloc null test
    - i2c: st: fix missing struct parameter description
    - firmware: arm_sdei: fix double-lock on hibernate with shared events
    - null_blk: Fix the null_add_dev() error path
    - null_blk: Handle null_add_dev() failures properly
    - null_blk: fix spurious IO errors after failed past-wp access
    - xhci: bail out early if driver can't accress host in resume
    - x86: Don't let pgprot_modify() change the page encryption bit
    - block: keep bdi->io_pages in sync with max_sectors_kb for stacked devices
    - irqchip/versatile-fpga: Handle chained IRQs properly
    - sched: Avoid scale real weight down to zero
    - selftests/x86/ptrace_syscall_32: Fix no-vDSO segfault
    - PCI/switchtec: Fix init_completio...