test_timerfd_negative hangs indefinitely, causes system freeze on NetBSD

[furkanonder]

Bug report

Bug description:

When running the test_timerfd_negative test from test_os.TimerfdTests, the test process hangs indefinitely, cannot be interrupted with Control-C or Control-D, and eventually causes the entire system to freeze.

Configuration:

./configure --with-pydebug

Test

./python -m test test_os -m test_timerfd_negative -v

Output:

== CPython 3.14.0a6+ (heads/main:26511993e63, Mar 15 2025, 00:00:15) [GCC 10.5.0]
== NetBSD-10.0-amd64-x86_64-64bit-ELF little-endian
== Python build: debug
== cwd: /home/blue/cpython/build/test_python_worker_20759æ
== CPU count: 16
== encodings: locale=UTF-8 FS=utf-8
== resources: all test resources are disabled, use -u option to unskip tests
Using random seed: 886729535
0:00:00 load avg: 0.19 Run 1 test sequentially in a single process
0:00:00 load avg: 0.19 [1/1] test_os
test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) ...
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=0, initial=-1, interval=0) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=1, initial=-1, interval=0) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=3, initial=-1, interval=0) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=0, initial=1, interval=-1) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=1, initial=1, interval=-1) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=3, initial=1, interval=-1) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=0, initial=-1, interval=-1) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=1, initial=-1, interval=-1) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=3, initial=-1, interval=-1) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=0, initial=-0.1, interval=0) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=1, initial=-0.1, interval=0) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=3, initial=-0.1, interval=0) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=0, initial=1, interval=-0.1) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=1, initial=1, interval=-0.1) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=3, initial=1, interval=-0.1) ... FAIL
  test_timerfd_negative (test.test_os.TimerfdTests.test_timerfd_negative) (flags=0, initial=-0.1, interval=-0.1) ... FAIL

OS: NetBSD-10.0-amd64

CPython versions tested on:

CPython main branch, 3.13, 3.14

Operating systems tested on:

Other

Linked PRs

• gh-131263: Skip test_timerfd_negative on NetBSD to prevent system freeze #131431
• [3.13] gh-131263: Skip test_timerfd_negative on NetBSD to prevent system freeze (GH-131431) #131451

[zware]

That seems like a platform bug; the test is just checking that OSError is raised for nonsensical arguments.

More interestingly, that entire test class is supposed to be skipped except on Linux >=2.6.30, why isn't it?

cc @vstinner, ref gh-108277

[vstinner]

More interestingly, that entire test class is supposed to be skipped except on Linux >=2.6.30, why isn't it?

@support.requires_linux_version(2, 6, 30) only skips the test on Linux if the kernel is too old.

[vstinner]

When running the test_timerfd_negative test from test_os.TimerfdTests, the test process hangs indefinitely, cannot be interrupted with Control-C or Control-D, and eventually causes the entire system to freeze.

I suggest to skip the test on NetBSD with a reference to this issue.

@furkanonder: Do you want to propose a fix?

[furkanonder]

When running the test_timerfd_negative test from test_os.TimerfdTests, the test process hangs indefinitely, cannot be interrupted with Control-C or Control-D, and eventually causes the entire system to freeze.

I suggest to skip the test on NetBSD with a reference to this issue.

@furkanonder: Do you want to propose a fix?

I opened a PR to skip the test on NetBSD.