Process Process-1:
Traceback (most recent call last):
  File "/usr/local/lib/python3.11/multiprocessing/process.py", line 314, in _bootstrap
    self.run()
  File "/usr/local/lib/python3.11/multiprocessing/process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
  File "/io/pyi_multiprocessing_nested_process.py", line 15, in process_function
    process.start()
  File "/usr/local/lib/python3.11/multiprocessing/process.py", line 121, in start
    self._popen = self._Popen(self)
                  ^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/multiprocessing/context.py", line 224, in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/multiprocessing/context.py", line 288, in _Popen
    return Popen(process_obj)
           ^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/multiprocessing/popen_spawn_posix.py", line 32, in __init__
    super().__init__(process_obj)
  File "/usr/local/lib/python3.11/multiprocessing/popen_fork.py", line 19, in __init__
    self._launch(process_obj)
  File "/usr/local/lib/python3.11/multiprocessing/popen_spawn_posix.py", line 47, in _launch
    reduction.dump(process_obj, fp)
  File "/usr/local/lib/python3.11/multiprocessing/reduction.py", line 60, in dump
    ForkingPickler(file, protocol).dump(obj)
  File "/usr/local/lib/python3.11/multiprocessing/synchronize.py", line 106, in __getstate__
    if self.is_fork_ctx:
       ^^^^^^^^^^^^^^^^
AttributeError: 'Lock' object has no attribute 'is_fork_ctx'
Results: [1]

import sys
import multiprocessing


def nested_process_function(queue):
    print("Running nested sub-process!")
    queue.put(2)


def process_function(queue):
    print("Running sub-process!")
    queue.put(1)

    process = multiprocessing.Process(target=nested_process_function, args=(queue,))
    process.start()
    process.join()


def main(start_method):
    multiprocessing.set_start_method(start_method)
    queue = multiprocessing.Queue()

    process = multiprocessing.Process(target=process_function, args=(queue,))
    process.start()
    process.join()

    results = []
    while not queue.empty():
        results.append(queue.get())

    print(f"Results: {results}")
    assert results == [1, 2]


if __name__ == '__main__':
    if len(sys.argv) != 2:
        raise SystemExit(f"Usage: {sys.argv[0]} fork|forkserver|spawn")

    main(sys.argv[1])

diff --git a/Lib/multiprocessing/synchronize.py b/Lib/multiprocessing/synchronize.py
index 2328d33212..9c5c2aada6 100644
--- a/Lib/multiprocessing/synchronize.py
+++ b/Lib/multiprocessing/synchronize.py
@@ -109,10 +109,11 @@ def __getstate__(self):
                                    'not supported. Please use the same context to create '
                                    'multiprocessing objects and Process.')
             h = sl.handle
-        return (h, sl.kind, sl.maxvalue, sl.name)
+        return (h, sl.kind, sl.maxvalue, sl.name, self.is_fork_ctx)
 
     def __setstate__(self, state):
-        self._semlock = _multiprocessing.SemLock._rebuild(*state)
+        self._semlock = _multiprocessing.SemLock._rebuild(*state[:4])
+        self.is_fork_ctx = state[4]
         util.debug('recreated blocker with handle %r' % state[0])
         self._make_methods()

### Tasks