4.18.0 kernels hang system randomly

[TJ]

I've been using 18.04 on an Asus T300CHI without issue until I decided to switch to the v4.18 kernels from 18.10 via linux-image-lowlatency-hwe-18.04-edge.

Since then the system randomly but regularly completely hangs. Only a hard power-off resolves it.

Frustratingly there are never any clues in the kernel logs so it is very difficult to point to anything that might cause it; there is never any obvious pattern in the workload, the user interaction, or state of the PC when the hang occurs.

A week ago I switched to the Ubuntu mainline v4.19 builds and that resolved the issue.

I was reminded of it again today when it hung a few minutes ago. After the reboot I checked the previous boot log and realised the PC had accidentally been booted with the default v4.18 kernel rather than v4.19.

I don't think this report can be debugged but it is worth having a tracking bug in case other people experience the same issue with v4.18.

[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 1803960

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.

[TJ (tj)]

I've been using the 4.18.0-12-lowlatency kernel from cosmic and not had any freeze-ups in the last 48 hours. I'll continue monitoring and report back after a few more days.

Because there are lots of reports of Intel Baytrail CPUs suffering freezes due to c-states I want to make clear the CPU here is Broadwell:

model name : Intel(R) Core(TM) M-5Y71 CPU @ 1.20GHz

[TJ (tj)]

Just experienced the same symptom of a complete, silent, freeze with:

-- Logs begin at Sun 2018-04-01 13:42:23 BST, end at Wed 2018-11-28 10:33:23 GMT. --
Nov 20 10:48:10 T300CHI kernel: microcode: microcode updated early to revision 0x2b, date = 2018-03-22
Nov 20 10:48:10 T300CHI kernel: Linux version 4.18.0-12-lowlatency (buildd@lgw01-amd64-033) (gcc version 8.2.0 (Ubuntu 8.2.0-7ubuntu1)) #13-
Nov 20 10:48:10 T300CHI kernel: Command line: BOOT_IMAGE=/vmlinuz-4.18.0-12-lowlatency root=/dev/mapper/VG02-rootfs ro no_console_suspend acpi_osi=! "acpi_osi=Windows 2013" splash vt.handoff=7
...
Nov 20 10:48:10 T300CHI kernel: efi: EFI v2.40 by American Megatrends
Nov 20 10:48:10 T300CHI kernel: efi: ESRT=0xcee2dd98 ACPI=0xcd72b000 ACPI 2.0=0xcd72b000 SMBIOS=0xf05b0 MPS=0xfd6e0
Nov 20 10:48:10 T300CHI kernel: secureboot: Secure boot could not be determined (mode 0)
...
Nov 20 10:48:10 T300CHI kernel: smpboot: CPU0: Intel(R) Core(TM) M-5Y71 CPU @ 1.20GHz (family: 0x6, model: 0x3d, stepping: 0x4)

[TJ (tj)]

This hang is affecting all mainline builds (from the kernel PPA) up to and including 4.20-rc4.

The only version that doesn't appear to be affected is 4.15.0-38-lowlatency.

I'll start working backward from the 4.18* versions to try to narrow where the apparent regression begins so that a bisect will be easier.

[TJ (tj)]

Five days running on 4.16.18-041618-lowlatency and had no problems so I'm going to try the mainline build of v4.17.19.

[TJ (tj)]

I almost forgot about this; 4.17.19-041719-lowlatency has been running fine now for 16 days. I'm going to switch to 4.18.0-13-lowlatency and confirm the problem still exists.

[TJ (tj)]

Continuing issues up to and including 5.0.0-8. Experienced three lock-ups today.

I strongly suspect the iwlwifi device but as the lock up is total and silent there are zero clues.