This panic occurred while running the ubuntu_kernel_selftests suite. The last bit of logs are:

13:33:20 DEBUG| [stdout] # selftests: ftrace: ftracetest
13:33:20 DEBUG| [stdout] # === Ftrace unit tests ===
13:33:28 DEBUG| [stdout] # [1] Basic trace file check [PASS]
13:37:04 DEBUG| [stdout] # [2] Basic test for tracers [PASS]
13:39:48 DEBUG| [stdout] # [3] Basic trace clock test [PASS]
13:39:56 DEBUG| [stdout] # [4] Basic event tracing check [PASS]
13:40:04 DEBUG| [stdout] # [5] Change the ringbuffer size [PASS]
13:40:20 DEBUG| [stdout] # [6] Snapshot and tracing setting [PASS]
13:40:35 DEBUG| [stdout] # [7] trace_pipe and trace_marker [PASS]
13:40:51 DEBUG| [stdout] # [8] Generic dynamic event - add/remove kprobe events [PASS]
13:41:07 DEBUG| [stdout] # [9] Generic dynamic event - add/remove synthetic events [PASS]
13:41:14 DEBUG| [stdout] # [10] Generic dynamic event - selective clear (compatibility) [PASS]
13:41:22 DEBUG| [stdout] # [11] Generic dynamic event - generic clear event [PASS]
13:41:46 DEBUG| [stdout] # [12] event tracing - enable/disable with event level files [PASS]
13:42:17 DEBUG| [stdout] # [13] event tracing - restricts events based on pid [PASS]
13:42:41 DEBUG| [stdout] # [14] event tracing - enable/disable with subsystem level files [PASS]
13:43:05 DEBUG| [stdout] # [15] event tracing - enable/disable with top level files [PASS]
13:43:14 DEBUG| [stdout] # [16] Test trace_printk from module [PASS]
13:43:56 DEBUG| [stdout] # [17] ftrace - function graph filters with stack tracer [PASS]
13:44:29 DEBUG| [stdout] # [18] ftrace - function graph filters [PASS]
13:45:49 DEBUG| [stdout] # [19] ftrace - function pid filters [PASS]
13:46:06 DEBUG| [stdout] # [20] ftrace - stacktrace filter command [PASS]
13:46:38 DEBUG| [stdout] # [21] ftrace - function trace with cpumask [PASS]
13:47:13 DEBUG| [stdout] # [22] ftrace - test for function event triggers [PASS]
13:47:21 DEBUG| [stdout] # [23] ftrace - function trace on module [PASS]
13:47:31 DEBUG| [stdout] # [24] ftrace - function profiling [PASS]
13:48:07 DEBUG| [stdout] # [25] ftrace - function profiler with function tracing [PASS]
13:48:25 DEBUG| [stdout] # [26] ftrace - test reading of set_ftrace_filter [PASS]
---- END OF MESSAGES ----

This job was run twice. The prior run also hung before completing, but we don't have a console log for that time period, so it's unclear if it also panic'd. It's last messages were:

04:44:27 DEBUG| [stdout] # selftests: timers: nsleep-lat
04:44:48 DEBUG| [stdout] # nsleep latency CLOCK_REALTIME [OK]
04:45:09 DEBUG| [stdout] # nsleep latency CLOCK_MONOTONIC [OK]
04:45:09 DEBUG| [stdout] # nsleep latency CLOCK_MONOTONIC_RAW [UNSUPPORTED]
04:45:09 DEBUG| [stdout] # nsleep latency CLOCK_REALTIME_COARSE [UNSUPPORTED]
04:45:09 DEBUG| [stdout] # nsleep latency CLOCK_MONOTONIC_COARSE [UNSUPPORTED]
04:45:30 DEBUG| [stdout] # nsleep latency CLOCK_BOOTTIME [OK]
04:45:52 DEBUG| [stdout] # nsleep latency CLOCK_REALTIME_ALARM [OK]
04:46:13 DEBUG| [stdout] # nsleep latency CLOCK_BOOTTIME_ALARM [OK]
04:46:34 DEBUG| [stdout] # nsleep latency CLOCK_TAI [OK]
04:46:34 DEBUG| [stdout] # # Pass 0 Fail 0 Xfail 0 Xpass 0 Skip 0 Error 0
04:46:34 DEBUG| [stdout] ok 3 selftests: timers: nsleep-lat
04:46:34 DEBUG| [stdout] # selftests: timers: set-timer-lat