gh-141780: Make PyModule_FromSlotsAndSpec enable GIL if needed

Include/internal/pycore_import.h

@@ -128,11 +128,18 @@ PyAPI_FUNC(int) _PyImport_ClearExtension(PyObject *name, PyObject *filename);
 // state of the module argument:
 // - If module is NULL or a PyModuleObject with md_gil == Py_MOD_GIL_NOT_USED,
 //   call _PyEval_DisableGIL().
-// - Otherwise, call _PyEval_EnableGILPermanent(). If the GIL was not already
-//   enabled permanently, issue a warning referencing the module's name.
+// - Otherwise, call _PyImport_EnableGILAndWarn
 //
 // This function may raise an exception.
 extern int _PyImport_CheckGILForModule(PyObject *module, PyObject *module_name);
+// Assuming that the GIL is enabled from a call to
+// _PyEval_EnableGILTransient(), call _PyEval_EnableGILPermanent().
+// If the GIL was not already enabled permanently, issue a warning referencing
+// the module's name.
+// Leave a message in verbose mode.
+//
+// This function may raise an exception.
+extern int _PyImport_EnableGILAndWarn(PyThreadState *, PyObject *module_name);
 #endif
 
 #ifdef __cplusplus

Lib/test/test_import/__init__.py

@@ -1,4 +1,5 @@
 import builtins
+import concurrent.interpreters
 import errno
 import glob
 import json
@@ -3407,6 +3408,35 @@ def test_from_modexport(self):
 
         self.assertEqual(module.__name__, modname)
 
+    def test_from_modexport_gil_used(self):
+        # Test that a module with Py_MOD_GIL_USED (re-)enables the GIL.
+        # Do this in a new interpreter to avoid interfering with global state.
+        modname = '_test_from_modexport_gil_used'
+        filename = _testmultiphase.__file__
+        interp = concurrent.interpreters.create()
+        self.addCleanup(interp.close)
+        queue = concurrent.interpreters.create_queue()
+        interp.prepare_main(
+            modname=modname,
+            filename=filename,
+            queue=queue,
+        )
+        enabled_before = sys._is_gil_enabled()
+        interp.exec(f"""if True:
+            import sys
+            from {__name__} import import_extension_from_file
+            module = import_extension_from_file(modname, filename,
+                                                put_in_sys_modules=False)
+            queue.put(module.__name__)
+            queue.put(sys._is_gil_enabled())
+        """)
+
+        self.assertEqual(queue.get(), modname)
+        self.assertEqual(queue.get(), True)
+        self.assertTrue(queue.empty())
+
+        self.assertEqual(enabled_before, sys._is_gil_enabled())
+
     def test_from_modexport_null(self):
         modname = '_test_from_modexport_null'
         filename = _testmultiphase.__file__
@@ -3428,6 +3458,35 @@ def test_from_modexport_create_nonmodule(self):
                                             put_in_sys_modules=False)
         self.assertIsInstance(module, str)
 
+    def test_from_modexport_create_nonmodule_gil_used(self):
+        # Test that a module with Py_MOD_GIL_USED (re-)enables the GIL.
+        # Do this in a new interpreter to avoid interfering with global state.
+        modname = '_test_from_modexport_create_nonmodule_gil_used'
+        filename = _testmultiphase.__file__
+        interp = concurrent.interpreters.create()
+        self.addCleanup(interp.close)
+        queue = concurrent.interpreters.create_queue()
+        interp.prepare_main(
+            modname=modname,
+            filename=filename,
+            queue=queue,
+        )
+        enabled_before = sys._is_gil_enabled()
+        interp.exec(f"""if True:
+            import sys
+            from {__name__} import import_extension_from_file
+            module = import_extension_from_file(modname, filename,
+                                                put_in_sys_modules=False)
+            queue.put(module)
+            queue.put(sys._is_gil_enabled())
+        """)
+
+        self.assertIsInstance(queue.get(), str)
+        self.assertEqual(queue.get(), True)
+        self.assertTrue(queue.empty())
+
+        self.assertEqual(enabled_before, sys._is_gil_enabled())
+
     def test_from_modexport_smoke(self):
         # General positive test for sundry features
         # (PyModule_FromSlotsAndSpec tests exercise these more carefully)

Lib/test/test_importlib/util.py

@@ -15,7 +15,8 @@
 import tempfile
 import types
 
-_testsinglephase = import_helper.import_module("_testsinglephase")
+# gh-116303: Skip test module dependent tests if test modules are unavailable
+import_helper.import_module("_testmultiphase")
 
 
 BUILTINS = types.SimpleNamespace()

Misc/NEWS.d/next/Core_and_Builtins/2025-11-20-13-18-57.gh-issue-141780.xDrVNr.rst

@@ -0,0 +1,2 @@
+Fix :c:macro:`Py_mod_gil` with API added in :pep:`793`:
+:c:func:`!PyModule_FromSlotsAndSpec` and ``PyModExport`` hooks

Modules/_testmultiphase.c

@@ -1024,6 +1024,20 @@ PyModExport__test_from_modexport(void)
 {
     static PyModuleDef_Slot slots[] = {
         {Py_mod_name, "_test_from_modexport"},
+        {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
+        {Py_mod_gil, Py_MOD_GIL_NOT_USED},
+        {0},
+    };
+    return slots;
+}
+
+PyMODEXPORT_FUNC
+PyModExport__test_from_modexport_gil_used(void)
+{
+    static PyModuleDef_Slot slots[] = {
+        {Py_mod_name, "_test_from_modexport_gil_used"},
+        {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
+        {Py_mod_gil, Py_MOD_GIL_USED},
         {0},
     };
     return slots;
@@ -1073,6 +1087,21 @@ PyModExport__test_from_modexport_create_nonmodule(void)
     static PyModuleDef_Slot slots[] = {
         {Py_mod_name, "_test_from_modexport_create_nonmodule"},
         {Py_mod_create, modexport_create_string},
+        {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
+        {Py_mod_gil, Py_MOD_GIL_NOT_USED},
+        {0},
+    };
+    return slots;
+}
+
+PyMODEXPORT_FUNC
+PyModExport__test_from_modexport_create_nonmodule_gil_used(void)
+{
+    static PyModuleDef_Slot slots[] = {
+        {Py_mod_name, "_test_from_modexport_create_nonmodule"},
+        {Py_mod_create, modexport_create_string},
+        {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
+        {Py_mod_gil, Py_MOD_GIL_USED},
         {0},
     };
     return slots;
@@ -1165,6 +1194,8 @@ PyModExport__test_from_modexport_smoke(void)
         {Py_mod_methods, methods},
         {Py_mod_state_free, modexport_smoke_free},
         {Py_mod_token, (void*)&modexport_smoke_test_token},
+        {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
+        {Py_mod_gil, Py_MOD_GIL_NOT_USED},
         {0},
     };
     return slots;

Objects/moduleobject.c

@@ -2,6 +2,7 @@
 
 #include "Python.h"
 #include "pycore_call.h"          // _PyObject_CallNoArgs()
+#include "pycore_ceval.h"         // _PyEval_EnableGILTransient()
 #include "pycore_dict.h"          // _PyDict_EnablePerThreadRefcounting()
 #include "pycore_fileutils.h"     // _Py_wgetcwd
 #include "pycore_import.h"        // _PyImport_GetNextModuleIndex()
@@ -522,6 +523,22 @@ module_from_def_and_spec(
 #undef COPY_COMMON_SLOT
     }
 
+#ifdef Py_GIL_DISABLED
+    // For modules created directly from slots (not from a def), we enable
+    // the GIL here (pairing `_PyEval_EnableGILTransient` with
+    // an immediate `_PyImport_EnableGILAndWarn`).
+    // For modules created from a def, the caller is responsible for this.
+    if (!original_def && requires_gil) {
+        PyThreadState *tstate = _PyThreadState_GET();
+        if (_PyEval_EnableGILTransient(tstate) < 0) {
+            goto error;
+        }
+        if (_PyImport_EnableGILAndWarn(tstate, nameobj) < 0) {
+            goto error;
+        }
+    }
+#endif
+
     /* By default, multi-phase init modules are expected
        to work under multiple interpreters. */
     if (!has_multiple_interpreters_slot) {

Python/import.c

@@ -1550,25 +1550,9 @@ _PyImport_CheckGILForModule(PyObject* module, PyObject *module_name)
     if (!PyModule_Check(module) ||
         ((PyModuleObject *)module)->md_requires_gil)
     {
-        if (_PyEval_EnableGILPermanent(tstate)) {
-            int warn_result = PyErr_WarnFormat(
-                PyExc_RuntimeWarning,
-                1,
-                "The global interpreter lock (GIL) has been enabled to load "
-                "module '%U', which has not declared that it can run safely "
-                "without the GIL. To override this behavior and keep the GIL "
-                "disabled (at your own risk), run with PYTHON_GIL=0 or -Xgil=0.",
-                module_name
-            );
-            if (warn_result < 0) {
-                return warn_result;
-            }
-        }
-
-        const PyConfig *config = _PyInterpreterState_GetConfig(tstate->interp);
-        if (config->enable_gil == _PyConfig_GIL_DEFAULT && config->verbose) {
-            PySys_FormatStderr("# loading module '%U', which requires the GIL\n",
-                               module_name);
+        assert(((PyModuleObject *)module)->md_token_is_def);
+        if (_PyImport_EnableGILAndWarn(tstate, module_name) < 0) {
+            return -1;
         }
     }
     else {
@@ -1577,6 +1561,27 @@ _PyImport_CheckGILForModule(PyObject* module, PyObject *module_name)
 
     return 0;
 }
+
+int
+_PyImport_EnableGILAndWarn(PyThreadState *tstate, PyObject *module_name) {
+    if (_PyEval_EnableGILPermanent(tstate)) {
+        return PyErr_WarnFormat(
+            PyExc_RuntimeWarning,
+            1,
+            "The global interpreter lock (GIL) has been enabled to load "
+            "module '%U', which has not declared that it can run safely "
+            "without the GIL. To override this behavior and keep the GIL "
+            "disabled (at your own risk), run with PYTHON_GIL=0 or -Xgil=0.",
+            module_name
+        );
+    }
+    const PyConfig *config = _PyInterpreterState_GetConfig(tstate->interp);
+    if (config->enable_gil == _PyConfig_GIL_DEFAULT && config->verbose) {
+        PySys_FormatStderr("# loading module '%U', which requires the GIL\n",
+                            module_name);
+    }
+    return 0;
+}
 #endif
 
 static PyThreadState *
@@ -4785,6 +4790,8 @@ _imp_create_dynamic_impl(PyObject *module, PyObject *spec, PyObject *file)
     _PyImport_GetModuleExportHooks(&info, fp, &p0, &ex0);
     if (ex0) {
         mod = import_run_modexport(tstate, ex0, &info, spec);
+        // Modules created from slots handle GIL enablement (Py_mod_gil slot)
+        // when they're created.
         goto cleanup;
     }
     if (p0 == NULL) {