3.15.0b2, openSUSE/Factory, s390x: failing test: test_os (test_timerfd_ns_poll)

Bug report

Bug description:

[15008s] 0:54:56 load avg: 1.03 Re-running 1 failed tests in verbose mode in subprocesses
[15008s] 0:54:56 load avg: 1.03 Run 1 test in parallel using 1 worker process (timeout: 1 hour 30 min, worker timeout: 1 hour 35 min)
[15009s] 0:54:59 load avg: 1.02 [1/1/1] test.test_os.test_os failed (1 failure)
[15009s] Re-running test.test_os.test_os in verbose mode (matching: test_timerfd_ns_poll)
[15009s] test_timerfd_ns_poll (test.test_os.test_os.TimerfdTests.test_timerfd_ns_poll) ... FAIL
[15009s] 
[15009s] ======================================================================
[15009s] FAIL: test_timerfd_ns_poll (test.test_os.test_os.TimerfdTests.test_timerfd_ns_poll)
[15009s] ----------------------------------------------------------------------
[15009s] Traceback (most recent call last):
[15009s]   File "/home/abuild/rpmbuild/BUILD/python315-3.15.0_b2-build/Python-3.15.0b2/Lib/test/test_os/test_os.py", line 4304, in test_timerfd_ns_poll
[15009s]     self.check_timerfd_poll(True)
[15009s]     ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
[15009s]   File "/home/abuild/rpmbuild/BUILD/python315-3.15.0_b2-build/Python-3.15.0b2/Lib/test/test_os/test_os.py", line 4289, in check_timerfd_poll
[15009s]     self.assertEqual(self.read_count_signaled(fd), 1)
[15009s]     ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[15009s] AssertionError: 2 != 1
[15009s] 
[15009s] ----------------------------------------------------------------------
[15009s] Ran 1 test in 0.467s
[15009s] 
[15009s] FAILED (failures=1)

Complete build log

Is this about time-outs again? Is our build machine too slow again?

CPython versions tested on:

3.15

Operating systems tested on:

Linux

Start with Lib/test/test_os/test_os.py at TimerfdTests.test_timerfd_ns_poll and check_timerfd_poll, then review the linked build log and reproduce on Linux s390x. Done means identifying why the poll count is 2 instead of 1 and resolving the failing test.