ubuntu_kernel_selftests / ftrace:ftracetest hangs on arm64 on Jammy realtime

[Krzysztof Kozlowski]

d2021.10.26/jammy/linux-realtime/5.15.0-1004.4, only on node appleton-kernel.arm64, hangs (timeouts) on ubuntu_kernel_selftests / ftrace:ftracetest test:
--------
01:28:34 DEBUG| [stdout] # === Ftrace unit tests ===
01:28:34 DEBUG| [stdout] # [1] Basic trace file check [PASS]
01:28:38 DEBUG| [stdout] # [2] Basic test for tracers [PASS]
01:28:38 DEBUG| [stdout] # [3] Basic trace clock test [PASS]
01:28:38 DEBUG| [stdout] # [4] Basic event tracing check [PASS]
01:28:39 DEBUG| [stdout] # [5] Change the ringbuffer size [PASS]
01:28:39 DEBUG| [stdout] # [6] Snapshot and tracing setting [PASS]
01:28:40 DEBUG| [stdout] # [7] trace_pipe and trace_marker [PASS]
01:28:40 DEBUG| [stdout] # [8] Test ftrace direct functions against tracers [UNRESOLVED]
01:28:40 DEBUG| [stdout] # [9] Test ftrace direct functions against kprobes [UNRESOLVED]
01:28:40 DEBUG| [stdout] # [10] Generic dynamic event - add/remove eprobe events [PASS]
01:28:41 DEBUG| [stdout] # [11] Generic dynamic event - add/remove kprobe events [PASS]
01:28:41 DEBUG| [stdout] # [12] Generic dynamic event - add/remove synthetic events [PASS]
01:28:41 DEBUG| [stdout] # [13] Generic dynamic event - selective clear (compatibility) [PASS]
01:28:41 DEBUG| [stdout] # [14] Generic dynamic event - generic clear event [PASS]
01:28:42 DEBUG| [stdout] # [15] Generic dynamic event - check if duplicate events are caught [PASS]
01:58:36 INFO | Timer expired (1800 sec.), nuking pid 161336
--------

The issue was not reproduced on mcdivitt36 (HP ProLiant m400 server cartridge with AppliedMicro X-Gene 64-bit ARM).

[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 1959424

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.

[Krzysztof Kozlowski (krzk)]

Also: d2022.02.03/jammy/linux-realtime/5.15.0-1005.5 on dazzle.arm64 and helo-kernel.arm64

[Andrei Gherzan (agherzan)]

I have hit this on Focal too (kopter):

SRU Cycle: 2023.03.20
Series: focal
Package: linux-hwe-5.15
Version: 5.15.0-70.77~20.04.1
Instance: kopter-kernel