Comment 7 for bug 1744270

ubuntu@kernel01:~/cking$ uname -a
Linux kernel01 4.4.0-112-generic #135-Ubuntu SMP Fri Jan 19 11:48:07 UTC 2018 s390x s390x s390x GNU/Linux

Looks like the modules weren't built for the kernel. I tried the 4.4.0-112-generic and it works fine after re-installing the dkms modules:

ubuntu@kernel01:~/cking$ sudo apt-get install --reinstall lttng-modules-dkms

ubuntu@kernel01:~/cking$ sudo autotest/client/autotest-local autotest/client/tests/ubuntu_lttng_smoke_test/control
04:21:01 INFO | Writing results to /home/ubuntu/cking/autotest/client/results/default
04:21:01 INFO | START ---- ---- timestamp=1517304061 localtime=Jan 30 04:21:01
04:21:01 INFO | START ubuntu_lttng_smoke_test.lttng-smoke-test ubuntu_lttng_smoke_test.lttng-smoke-test timestamp=1517304061 localtime=Jan 30 04:21:01
04:21:08 ERROR| [stderr] [warning] Tracer discarded 18895 events between [04:21:04.967791464] and [04:21:05.094587794] in trace UUID edc5397baa392f43a990cbcc29bb2f82, at path: "/tmp/lttng-kernel-trace-36474-session/kernel", within stream id 0, at relative path: "channel0_3". You should consider recording a new trace with larger buffers or with fewer events enabled.
04:21:08 ERROR| [stderr] [warning] Tracer discarded 19530 events between [04:21:05.163582941] and [04:21:05.294597778] in trace UUID edc5397baa392f43a990cbcc29bb2f82, at path: "/tmp/lttng-kernel-trace-36474-session/kernel", within stream id 0, at relative path: "channel0_3". You should consider recording a new trace with larger buffers or with fewer events enabled.
04:21:08 INFO | == lttng smoke test of session create/destroy ==
04:21:08 INFO | Session test-kernel-session created.
04:21:08 INFO | Traces will be written in /tmp/lttng-kernel-trace-36474-session
04:21:08 INFO | PASSED (lttng create)
04:21:08 INFO | Session test-kernel-session destroyed
04:21:08 INFO | PASSED (lttng destroy)
04:21:08 INFO |
04:21:08 INFO | == lttng smoke test list kernel events ==
04:21:08 INFO | PASSED (lttng list --kernel)
04:21:08 INFO |
04:21:08 INFO | lttng smoke test trace open/close system calls SKIPPED for s390x
04:21:08 INFO |
04:21:08 INFO | == lttng smoke test trace context switches ==
04:21:08 INFO | Session test-kernel-session created.
04:21:08 INFO | Traces will be written in /tmp/lttng-kernel-trace-36474-session
04:21:08 INFO | PASSED (lttng create)
04:21:08 INFO | Kernel event sched_switch created in channel channel0
04:21:08 INFO | PASSED (lttng enable-event)
04:21:08 INFO | Tracing started for session test-kernel-session
04:21:08 INFO | PASSED (lttng start)
04:21:08 INFO | Waiting for data availability.
04:21:08 INFO | Tracing stopped for session test-kernel-session
04:21:08 INFO | PASSED (lttng stop)
04:21:08 INFO | Session test-kernel-session destroyed
04:21:08 INFO | PASSED (lttng destroy)
04:21:08 INFO | Found 81105 dd and 95334 context switches
04:21:08 INFO | PASSED (simple system call tracing with babeltrace)
04:21:08 INFO |
04:21:08 INFO | Summary: 8 passed, 0 failed
04:21:08 INFO | GOOD ubuntu_lttng_smoke_test.lttng-smoke-test ubuntu_lttng_smoke_test.lttng-smoke-test timestamp=1517304068 localtime=Jan 30 04:21:08 completed successfully
04:21:08 INFO | END GOOD ubuntu_lttng_smoke_test.lttng-smoke-test ubuntu_lttng_smoke_test.lttng-smoke-test timestamp=1517304068 localtime=Jan 30 04:21:08