VSOCK test_socket.testStream() fails on aarch64 Fedora Stable 3.x buildbot

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Example: https://buildbot.python.org/#/builders/125/builds/8159

ERROR: testStream (test.test_socket.ThreadedVSOCKSocketStreamTest.testStream)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/var/lib/buildbot/worker/cstratak-fedora-stable-aarch64/3.x.cstratak-fedora-stable-aarch64/build/Lib/test/test_socket.py", line 438, in _setUp
    self.__setUp()
    ~~~~~~~~~~~~^^
  File "/var/lib/buildbot/worker/cstratak-fedora-stable-aarch64/3.x.cstratak-fedora-stable-aarch64/build/Lib/test/test_socket.py", line 581, in setUp
    self.conn, self.connaddr = self.serv.accept()
                               ~~~~~~~~~~~~~~~~^^
  File "/var/lib/buildbot/worker/cstratak-fedora-stable-aarch64/3.x.cstratak-fedora-stable-aarch64/build/Lib/socket.py", line 299, in accept
    fd, addr = self._accept()
               ~~~~~~~~~~~~^^
TimeoutError: timed out

test.pythoninfo:

test_socket.HAVE_SOCKET_VSOCK: True
os.uname: posix.uname_result(sysname='Linux', nodename='fedora', release='6.18.13-200.fc43.aarch64', version='#1 SMP PREEMPT_DYNAMIC Thu Feb 19 18:50:42 UTC 2026', machine='aarch64')
platform.architecture: 64bit ELF
platform.freedesktop_os_release[ID]: fedora
platform.freedesktop_os_release[NAME]: Fedora Linux
platform.freedesktop_os_release[VARIANT_ID]: server
platform.freedesktop_os_release[VERSION]: 43 (Server Edition)
platform.freedesktop_os_release[VERSION_ID]: 43
platform.libc_ver: glibc 2.42
platform.platform: Linux-6.18.13-200.fc43.aarch64-aarch64-with-glibc2.42

Linked PRs

• gh-145548: Log vsock CID in test.pythoninfo #145588
• gh-145548: Use VMADDR_CID_LOCAL in VSOCK socket tests #145589
• [3.14] gh-145548: Use VMADDR_CID_LOCAL in VSOCK socket tests (GH-145589) #145593
• [3.13] gh-145548: Use VMADDR_CID_LOCAL in VSOCK socket tests (GH-145589) #145594
• [3.13] gh-145548: Don't use VMADDR_CID_LOCAL from socket #145735
• [3.12] gh-145548: Use VMADDR_CID_LOCAL in VSOCK socket tests (GH-145589) #145809
• [3.11] gh-145548: Use VMADDR_CID_LOCAL in VSOCK socket tests (GH-145589) (GH-145809) #148616
• [3.10] gh-145548: Use VMADDR_CID_LOCAL in VSOCK socket tests (GH-145589) (GH-145809) #148617

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Other Fedora buildbots are affected, examples:

• aarch64 Fedora Rawhide 3.x: https://buildbot.python.org/#/builders/339/builds/6949
• PPC64LE Fedora Rawhide 3.x: https://buildbot.python.org/#/builders/455/builds/7791

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AMD64 Fedora Stable 3.x:

• Build 9429 (success): os.uname: posix.uname_result(sysname='Linux', nodename='python-builder2-rawhide.osci.io', release='6.18.6-200.fc43.x86_64', version='#1 SMP PREEMPT_DYNAMIC Sun Jan 18 18:57:00 UTC 2026', machine='x86_64')
• Build 9430 (failure): os.uname: posix.uname_result(sysname='Linux', nodename='python-builder2-rawhide.osci.io', release='6.18.13-200.fc43.x86_64', version='#1 SMP PREEMPT_DYNAMIC Thu Feb 19 19:54:01 UTC 2026', machine='x86_64')

The kernel was upgraded from version 6.18.6-200 to 6.18.13-200.

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PPC64LE Fedora Stable 3.x.

build 6974 (success):

os.environ[HOME]: /home/buildbot
pwd.getpwuid(1002): pwd.struct_passwd(pw_name='buildbot', pw_passwd='x', pw_uid=1002, pw_gid=1002, pw_gecos='', pw_dir='/home/buildbot', pw_shell='/bin/bash')
...
platform.freedesktop_os_release[NAME]: Fedora Linux
platform.freedesktop_os_release[VERSION]: 42 (Server Edition)
platform.libc_ver: glibc 2.41
platform.platform: Linux-5.8.17-200.fc32.ppc64le-ppc64le-with-glibc2.41

build 6975 (failure):

os.environ[HOME]: /var/lib/buildbot/worker
pwd.getpwuid(985): pwd.struct_passwd(pw_name='buildbot-worker', pw_passwd='x', pw_uid=985, pw_gid=985, pw_gecos='Service account for the Buildbot worker', pw_dir='/var/lib/buildbot/worker', pw_shell='/sbin/nologin')
...
platform.freedesktop_os_release[NAME]: Fedora Linux
platform.freedesktop_os_release[VERSION]: 43 (Server Edition)
platform.libc_ver: glibc 2.42
platform.platform: Linux-5.8.17-200.fc32.ppc64le-ppc64le-with-glibc2.42

Fedora was upgraded from Fedora 42 to Fedora 43. And for example, the glibc version was upgraded from 2.41 to 2.42.

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Previous similar issue, in 2024: #119461

On AMD64 Fedora Stable 3.x, the /dev/vsock device exists and get_cid() returns 4294967295 which is VMADDR_CID_ANY (-1).

$ sudo virt-what
redhat
kvm

On PPC64LE Fedora Stable 3.x, the /dev/vsock device exists and get_cid() returns 4294967295 which is VMADDR_CID_ANY (-1).

$ sudo virt-what
kvm
ibm_power-kvm

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On s390x Fedora Stable 3.x, test_socket pass, the /dev/vsock device exists, and get_cid() returns 1 (socket.VMADDR_CID_LOCAL).