gh-131338: Disable new stack size code for non-glibc on linux. by bitdancer · Pull Request #134336 · python/cpython · GitHub

MUSL claims to support pthread_getattr_np, but the response returned is off by at least an order of magnitude compared to reality. This is apparently a long standing problem. MUSL also does not provide any way to detect directly that it is the libc. It would be possible to add things to configure to detect that MUSL is the compiler, but since this code has apparently caused problems for a lot of non-glibc platforms, it seems easier to just restrict it to glibc.

Issue: Stack overflow test errors in Alpine after GH-130398 #131338

MUSL claims to support pthread_getattr_np, but the response returned is off by at least an order of magnitude compared to reality. This is apparently a long standing problem. MUSL also does not provide any way to detect directly that it is the libc. It would be possible to add things to configure to detect that MUSL is the compiler, but since this code has caused problems for a lot of non-glibc platforms, it seems easier to just restrict it to glibc.

I don't think that this call is correct. It disables the call on FreeBSD.

Maybe check for "glibc or not Linux"?

That would fix it for alpine, but not for emscripten or wasi (but I don't know what they actually need). I'd rather see it as if glibc or freebsd, and get rid of the rest, but glibc or not linux would work for my immediate concern.

Well, let's start with fixing Alpine Linux.

OK, done. Also added an XXX comment, since I think this needs more investigation. I'll put it on my todo list to post to the musl mailing list about it.

This exempts alpine but doesn't affect, eg, FreeBSD.

LGTM

This looks good but it needs a news entry as it is a bugfix and needs to be backported to 3.14.

Co-authored-by: Victor Stinner <vstinner@python.org>

I have added a news entry to move this PR forward and get this merged soon, will run through buildbots and merge.

🤖 New build scheduled with the buildbot fleet by @kumaraditya303 for commit 6498d29 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F134336%2Fmerge

If you want to schedule another build, you need to add the 🔨 test-with-buildbots label again.

Kumar asked me to test libcst with this PR applied. I manually backported the substantive part of this PR to the 3.14 branch and built Python using pyenv in the musllinux docker container.

I still see the segfault: https://gist.github.com/ngoldbaum/16fb37188d049edcd18296f809241798.

Also looking close, I don't think the crash we saw in LibCST is caused by this, since we see it in 3.13, and I don't think the new stack size code ever went into 3.13?

Also looking close, I don't think the crash we saw in LibCST is caused by this, since we see it in 3.13, and I don't think the new stack size code ever went into 3.13?

Yes, it is present in 3.14 and above. Looking at the backtrace of libcst it seems unrelated to this, a better test candidate for this would be scipy as that currently errors out with RecursionError like in scipy/scipy#23172.

Thanks @bitdancer for the PR, and @kumaraditya303 for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖

…ux (pythonGH-134336) (cherry picked from commit 1e9b8f2) Co-authored-by: R. David Murray <rdmurray@bitdance.com> Co-authored-by: Kumar Aditya <kumaraditya@python.org> Co-authored-by: Victor Stinner <vstinner@python.org>

GH-137175 is a backport of this pull request to the 3.14 branch.

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot ARM64 Raspbian 3.x (tier-3) has failed when building commit 1e9b8f2.

What do you need to do:

Don't panic.
Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1678/builds/582) and take a look at the build logs.
Check if the failure is related to this commit (1e9b8f2) or if it is a false positive.
If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1678/builds/582

Failed tests:

test_embed

Failed subtests:

test_init_setpythonhome - test.test_embed.InitConfigTests.test_init_setpythonhome

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/Lib/test/test_embed.py", line 1455, in test_init_setpythonhome
    self.check_all_configs("test_init_setpythonhome", config,
    ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                           api=API_COMPAT, env=env)
                           ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/Lib/test/test_embed.py", line 947, in check_all_configs
    self.check_config(configs, expected_config)
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/Lib/test/test_embed.py", line 873, in check_config
    self.assertEqual(config, expected)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
AssertionError: {'argv': [''], 'base_exec_prefix': '/home/s[2395 chars]None} != {'_config_init': 1, 'isolated': False, 'use[2463 chars]alse}
  {'_config_init': 1,
   '_init_main': True,
   '_install_importlib': True,
   'argv': [''],
   'base_exec_prefix': '/home/stan/buildarea/3.x.stan-raspbian.nondebug/build',
   'base_executable': '/home/stan/buildbot/bin/python3',
   'base_prefix': '/home/stan/buildarea/3.x.stan-raspbian.nondebug/build',
   'buffered_stdio': True,
   'bytes_warning': 0,
   'check_hash_pycs_mode': 'default',
   'code_debug_ranges': True,
   'configure_c_stdio': False,
   'context_aware_warnings': 0,
   'cpu_count': -1,
   'dev_mode': False,
   'dump_refs': False,
   'dump_refs_file': None,
-  'exec_prefix': '/home/stan/buildbot',
+  'exec_prefix': '/home/stan/buildarea/3.x.stan-raspbian.nondebug/build',
   'executable': '/home/stan/buildbot/bin/python3',
   'faulthandler': False,
   'hash_seed': 0,
   'home': '/home/stan/buildarea/3.x.stan-raspbian.nondebug/build',
   'import_time': 0,
   'inspect': False,
   'install_signal_handlers': True,
   'int_max_str_digits': 4300,
   'interactive': False,
   'isolated': False,
   'malloc_stats': False,
   'module_search_paths': ['/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/target/lib/python315.zip',
                           '/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/Lib',
                           '/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/build/lib.linux-aarch64-3.15',
                           '/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/lib/python315.zip',
                           '/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/lib/python3.15',
                           '/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/lib/python3.15/lib-dynload'],
   'module_search_paths_set': True,
   'optimization_level': 0,
   'orig_argv': [],
   'parse_argv': False,
   'parser_debug': False,
   'pathconfig_warnings': True,
   'perf_profiling': 0,
   'platlibdir': 'lib',
-  'prefix': '/home/stan/buildbot',
+  'prefix': '/home/stan/buildarea/3.x.stan-raspbian.nondebug/build',
   'program_name': 'python3',
   'pycache_prefix': None,
   'pythonpath_env': '/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/target/lib/python315.zip:/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/Lib:/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/build/lib.linux-aarch64-3.15',
   'quiet': False,
   'remote_debug': True,
   'run_command': None,
   'run_filename': None,
   'run_module': None,
   'safe_path': False,
   'show_ref_count': False,
   'site_import': True,
   'skip_source_first_line': False,
   'stdlib_dir': '/home/stan/buildarea/3.x.stan-raspbian.nondebug/build/lib/python3.15',
   'sys_path_0': None,
   'thread_inherit_context': 0,
   'tracemalloc': 0,
   'use_environment': True,
   'use_frozen_modules': True,
   'use_hash_seed': False,
   'user_site_directory': True,
   'verbose': 0,
   'warn_default_encoding': False,
   'warnoptions': [],
   'write_bytecode': True,
   'xoptions': {}}

Buildbot fail is unrelated to this PR. I am temporarily disabling the bot till I find a solution.

…nux (GH-134336) (#137175) Co-authored-by: R. David Murray <rdmurray@bitdance.com> Co-authored-by: Kumar Aditya <kumaraditya@python.org> Co-authored-by: Victor Stinner <vstinner@python.org>

…ux (python#134336) Co-authored-by: Kumar Aditya <kumaraditya@python.org> Co-authored-by: Victor Stinner <vstinner@python.org>

…ibc linux (pythonGH-134336) (python#137175) Co-authored-by: R. David Murray <rdmurray@bitdance.com> Co-authored-by: Kumar Aditya <kumaraditya@python.org> Co-authored-by: Victor Stinner <vstinner@python.org>

bitdancer requested a review from markshannon as a code owner May 20, 2025 14:41

bedevere-app Bot mentioned this pull request May 20, 2025

Stack overflow test errors in Alpine after GH-130398 #131338

Closed

bedevere-app Bot added the awaiting core review label May 20, 2025

bitdancer requested a review from hoodmane May 20, 2025 14:42

vstinner reviewed May 20, 2025

View reviewed changes

Don't require glibc if it isn't linux.

d7262cc

This exempts alpine but doesn't affect, eg, FreeBSD.

bitdancer changed the title gh-131338: Disable new stack size code for non-glibc. gh-131338: Disable new stack size code for non-glibc on linux. Jun 15, 2025

vstinner approved these changes Jun 16, 2025

View reviewed changes

Comment thread Python/ceval.c Outdated

bedevere-app Bot added awaiting merge and removed awaiting core review labels Jun 16, 2025

Clarify why we check __glibc__.

5c55790

vstinner reviewed Jun 17, 2025

View reviewed changes

Comment thread Python/ceval.c Outdated

kumaraditya303 added the needs backport to 3.14 bugs and security fixes label Jun 21, 2025

kumaraditya303 added the interpreter-core (Objects, Python, Grammar, and Parser dirs) label Jun 25, 2025

kumaraditya303 and others added 2 commits July 25, 2025 22:22

Apply suggestion from @vstinner

ac92003

Co-authored-by: Victor Stinner <vstinner@python.org>

add news

733a28b

Merge branch 'main' into revert_new_stack_check_for_non_glibc-131338

6498d29

kumaraditya303 added the 🔨 test-with-buildbots Test PR w/ buildbots; report in status section label Jul 25, 2025

bedevere-bot removed the 🔨 test-with-buildbots Test PR w/ buildbots; report in status section label Jul 25, 2025

ngoldbaum added a commit to ngoldbaum/cpython that referenced this pull request Jul 25, 2025

manually backport pythongh-134336

3654633

kumaraditya303 approved these changes Jul 28, 2025

View reviewed changes

kumaraditya303 merged commit 1e9b8f2 into python:main Jul 28, 2025

bedevere-app Bot removed the awaiting merge label Jul 28, 2025

bedevere-app Bot removed the needs backport to 3.14 bugs and security fixes label Jul 28, 2025

vstinner mentioned this pull request Apr 8, 2026

test_threading.test_recursion_limit() does crash (segfault) on Alpine Linux (musl) #148260

Closed

Yhg1s mentioned this pull request Oct 13, 2026

Broken stack size detection on Android #159320

Open

serhiy-storchaka mentioned this pull request Oct 20, 2026

C stack limit detection is disabled on musl, so deep C recursion crashes instead of raising RecursionError #159876

Open

                   uintptr_t here_addr = _Py_get_machine_stack_pointer();
-              #  if defined(HAVE_PTHREAD_GETATTR_NP) && !defined(_AIX) && !defined(__NetBSD__)
+              #  if defined(HAVE_PTHREAD_GETATTR_NP) && !defined(_AIX) && \
+                      !defined(__NetBSD__) && defined(__GLIBC__)

gh-131338: Disable new stack size code for non-glibc on linux. by bitdancer · Pull Request #134336 · python/cpython · GitHub

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gh-131338: Disable new stack size code for non-glibc on linux. - #134336

gh-131338: Disable new stack size code for non-glibc on linux.#134336kumaraditya303 merged 6 commits intopython:mainpython/cpython:mainfrom bitdancer:revert_new_stack_check_for_non_glibc-131338bitdancer/cpython:revert_new_stack_check_for_non_glibc-131338Copy head branch name to clipboard

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⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

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gh-131338: Disable new stack size code for non-glibc on linux.#134336
kumaraditya303 merged 6 commits into
python:mainfrom
bitdancer:revert_new_stack_check_for_non_glibc-131338

bitdancer commented May 20, 2025 •
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