canonical-ubuntu-qa team mailing list archive

[Po-Hsu Lin <2029405@xxxxxxxxxxxxxxxxxx>]

Hints removed. Closing this bug.

This issue cannot be found on J-azure, J-azure-fips, J-gcp-fips, J-mtk,
J-nvidia-tegra, J-xilinx.

We don't run this test on J-raspi, J-bluefield.

** Changed in: ubuntu-kernel-tests
       Status: In Progress => Fix Released

** Tags removed: verification-needed-jammy-linux-azure verification-needed-jammy-linux-azure-fips verification-needed-jammy-linux-bluefield verification-needed-jammy-linux-gcp-fips verification-needed-jammy-linux-mtk verification-needed-jammy-linux-nvidia-tegra verification-needed-jammy-linux-raspi verification-needed-jammy-linux-xilinx-zynqmp
** Tags added: verification-done-jammy-linux-azure verification-done-jammy-linux-azure-fips verification-done-jammy-linux-bluefield verification-done-jammy-linux-gcp-fips verification-done-jammy-linux-mtk verification-done-jammy-linux-nvidia-tegra verification-done-jammy-linux-raspi verification-done-jammy-linux-xilinx-zynqmp

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https://bugs.launchpad.net/bugs/2029405

Title:
  Change in trace file leads to test timeout in ftrace tests on 5.15
  ARM64

Status in ubuntu-kernel-tests:
  Fix Released
Status in linux package in Ubuntu:
  Fix Released
Status in linux source package in Jammy:
  Fix Released

Bug description:
  [Impact]
  On ARM64 systems, tests like subsystem-enable.tc, event-enable.tc,
  event-pid.tc in linux/tools/testing/selftests/ftrace will take too
  much time to run and consequently leads to test timeout.

  The culprit is the `cat` command on the changing trace file.

  [Fix]
  * 25b9513872 selftests/ftrace: Stop tracing while reading the trace
    file by default

  This patch can be cherry-picked into Jammy. I didn't see this issue in
  our 5.4 kernels. And it's already landed in newer kernels.

  [Test]
  On an ARM64 testing node, apply this patch to the kernel tree and run
  event-pid.tc test in linux/tools/testing/selftests/ftrace with:

    sudo ./ftracetest -vvv test.d/event/event-pid.tc

  The test should finish within a few minutes.

  [Regression Potential]
  Change limited to testing tools, it should not have any actual impact
  to kernel functions.

  == Original Bug Report ==
  First time seen this since ftrace refactor out from ubuntu_kernel_selftests to ubuntu-kselftests-ftrace

  Issue found on ARM64 nodes with both generic / generic-64k kernel.

  Partial test log:
   Running './ftracetest -vvv test.d/event/subsystem-enable.tc'
   === Ftrace unit tests ===
   ....
   [1] event tracing - enable/disable with event level files
   + [ 2 -eq 1 ]
   + [ -f set_event_pid ]
   + echo
   + [ -f set_ftrace_pid ]
   + echo
   + [ -f set_ftrace_notrace ]
   + echo
   + [ -f set_graph_function ]
   + echo
   + tee set_graph_function set_graph_notrace
   + [ -f stack_trace_filter ]
   + echo
   + [ -f kprobe_events ]
   + echo
   + [ -f uprobe_events ]
   + echo
   + [ -f synthetic_events ]
   + echo
   + [ -f snapshot ]
   + echo 0
   + clear_trace
   + echo
   + enable_tracing
   + echo 1
   + . /home/ubuntu/autotest/client/tmp/ubuntu_kselftests_ftrace/src/linux/tools/testing/selftests/ftrace/test.d/event/event-enable.tc
   + echo sched:sched_switch
   + yield
   + ping 127.0.0.1 -c 1
   PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
   64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.096 ms

   --- 127.0.0.1 ping statistics ---
   1 packets transmitted, 1 received, 0% packet loss, time 0ms
   rtt min/avg/max/mdev = 0.096/0.096/0.096/0.000 ms
   + cat trace
   + grep sched_switch
   + wc -l
   Timer expired (600 sec.), nuking pid 20982

  From the code (tools/testing/selftests/ftrace/test.d/event/event-
  enable.tc) this test is trying to run:

      count=`cat trace | grep sched_switch | wc -l`

  This command caused the timeout as `cat trace` seems to be never
  ending.

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