Segmentation fault on major GC collection if GC hooks are installed

[Yevhenii-Yatchenko]

Dears,

I've noticed a segmentation fault if GC hooks are installed.

STR:

1. Install GC hooks according to https://doc.pypy.org/en/latest/gc_info.html

2. Load the interpreter with some data operations to trigger GC Major collection.

> pypy3.6-gdb 1.py
PyPy assertion failed at rpython_memory_gc.c:5149:
in pypy_g_IncrementalMiniMarkGC_collect_oldrefs_to_nursery: old_objects_pointing_to_young contains obj with GCFLAG_TRACK_YOUNG_PTRS
Aborted (core dumped)

3. Process dies with a core dump.

PyPy version:

> pypy3.6-gdb
Python 3.6.9 (6c09c80243d4, Feb 15 2024, 20:40:35)
[PyPy 7.3.1 with GCC 12.2.1 20221121 (Red Hat 12.2.1-7.4.0.2)] on linux

The code that reproduces the issue:

import gc
import random
from time import sleep


class _Hooks:

    def on_gc_minor(self, *args, **kwargs):
        pass

    def on_gc_collect_step(self, *args, **kwargs):
        pass

    def on_gc_collect(self, *args, **kwargs):
        pass


gc.hooks.set(_Hooks())


def getRandomString(length):
    return ','.join([random.choice('abc') for _ in range(length)])


def doJob():
    a = ''
    for _ in range(1000):
        a = getRandomString(100)

    return a

counter = 0
while True:
    counter += 0

    doJob()

    sleep(1)
    print(counter)

Please let me know if additional info is required.

[Yevhenii-Yatchenko]

Attaching a file with the bt from coredump.
coredump_bt.txt

[devdanzin]

I can't reproduce with the official 7.3.1 build from https://downloads.python.org/pypy/pypy3.6-v7.3.1-linux64.tar.bz2 on WSL (Ubuntu), can you?

Python 3.6.9 (2ad108f17bdb, Apr 07 2020, 02:59:05)
[PyPy 7.3.1 with GCC 7.3.1 20180303 (Red Hat 7.3.1-5)] on linux

Maybe it only triggers on debug builds?

[cfbolz]

Maybe it only triggers on debug builds?

the backtrace shows an RPyAssertFailed, so yes, this would only trigger during debug builds.

[Yevhenii-Yatchenko]

I tried locally with the proposed PyPy binary and the one I had before - I can not reproduce this issue if the interpreter is built without debug headers.

But if debug headers are present - we need to choose between using hooks or trying to get the actual core dump, for which the debug headers were added.

[cfbolz]

OK, the above PR should fix this issue on pypy2. Will merge into the 3.9 and 3.10 branches as soon as my home internet gets fixed.

[mattip]

Closing since the 7.3.16 release has this fix. Please reopen if I misunderstood