Description

ZeroIntensity

opened on Sep 27, 2026

Issue body actions

Bug report

Bug description:

Saw in #157045 (specifically 5693c85). Failing builds seem to be only on Fedora s390x. For example:

• https://buildbot.python.org/#/builders/1634/builds/579
• https://buildbot.python.org/#/builders/1666/builds/579
• https://buildbot.python.org/#/builders/1643/builds/580
• https://buildbot.python.org/#/builders/1640/builds/582
• https://buildbot.python.org/#/builders/1652/builds/583
• https://buildbot.python.org/#/builders/1630/builds/674

Here's the traceback:

======================================================================
FAIL: test_function_entry_return (test.test_dtrace.SystemTapNormalTests.test_function_entry_return)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/var/lib/buildbot/worker/cstratak-fedora-stable-s390x/pull_request.cstratak-fedora-stable-s390x.refleak/build/Lib/test/test_dtrace.py", line 466, in test_function_entry_return
    self.run_case("call_stack")
    ~~~~~~~~~~~~~^^^^^^^^^^^^^^
  File "/var/lib/buildbot/worker/cstratak-fedora-stable-s390x/pull_request.cstratak-fedora-stable-s390x.refleak/build/Lib/test/test_dtrace.py", line 463, in run_case
    self.assertEqual(actual_output, expected_output)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 'func[21 chars]k.py:function_1:1\nfunction__entry:call_stack.[642 chars]5:21' != 'func[21 chars]k.py:start:23\nfunction__entry:call_stack.py:f[723 chars]t:28'

I'm unsure whether this is a known issue already, but I couldn't find any existing reports.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-158294: Avoid relying on SystemTap probe handler ordering #158346
• [3.15] gh-158294: Avoid relying on SystemTap probe handler ordering (GH-158346) #158383

Activity

1. ZeroIntensity

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   OS-unsupported

   on Sep 27, 2026
2. github-project-automation

   added this to Unsupported platformson Sep 27, 2026
3. hugovk commented on Sep 28, 2026

   

   hugovk

   on Sep 28, 2026

   Member

   More actions

   cc @stratakis @vstinner
4. aisk

   added

   testsTests in the Lib/test dirTests in the Lib/test dir

   on Sep 28, 2026
5. stratakis commented on Sep 28, 2026

   

   stratakis

   on Sep 28, 2026

   Contributor

   More actions

   This is an issue with the latest systemtap 5.6, the s390x got the update. From its changelog:

   Pass-2 optimizer can combine multiple probe handlers that share the same probe point, reducing registration overhead.
   

   call_stack.stp defines handlers to be run in specific order but Systemtap makes no guarantees about that and the latest version exposed the issue. Combining the logic there into one handler should fix it.

   Reacted by Victor Stinner
6. hugovk

   added 2 commits that reference this issue on Sep 29, 2026

   gh-158294: Avoid relying on SystemTap probe handler ordering (#158346)

   ec49d01

   [3.15] gh-158294: Avoid relying on SystemTap probe handler ordering (G…

   19c77ca
7. encukou commented on Sep 29, 2026

   

   encukou

   on Sep 29, 2026

   Member

   More actions

   Thank you for the fix!

   The redness is down to one slow refleaks bot; time to close.
8. encukou

   closed this as completedon Sep 29, 2026
9. encukou

   removed

   OS-unsupported

   on Oct 30, 2026
10. encukou

    removed this from Unsupported platformson Oct 30, 2026

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