From 5e5297640f54c3c44271b7563ea6a39fca2662be Mon Sep 17 00:00:00 2001
From: Timofey Ivankov <playboicartina@gmail.com>
Date: Fri, 3 Jul 2026 22:35:30 +0300
Subject: [PATCH 1/2] gh-152083: Fix crash clearing a managed dict under low
 memory

---
 Lib/test/test_class.py                        | 30 +++++++++++++++++++
 ...-07-03-22-32-58.gh-issue-152083.nSAuhO.rst |  2 ++
 Objects/dictobject.c                          |  4 +++
 3 files changed, 36 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2026-07-03-22-32-58.gh-issue-152083.nSAuhO.rst

diff --git a/Lib/test/test_class.py b/Lib/test/test_class.py
index e401941c6d69700..51f99f9b0d492c9 100644
--- a/Lib/test/test_class.py
+++ b/Lib/test/test_class.py
@@ -1040,5 +1040,35 @@ def __init__(self):
         self.assertFalse(out, msg=out.decode('utf-8'))
         self.assertFalse(err, msg=err.decode('utf-8'))
 
+    @support.nomemtest
+    def test_clear_managed_dict_no_memory_keeps_exception(self):
+        # gh-152083: an exception may already be set when the managed dict is
+        # cleared under low memory. PyErr_FormatUnraisable() must not clear it.
+        code = """if 1:
+            import _testcapi
+
+            class A:
+                def __init__(self):
+                    self.a = 1
+                    self.b = 2
+
+            def f():
+                a = A()
+                a.__dict__
+                return [None] * 1000
+
+            for start in range(120):
+                _testcapi.set_nomemory(start)
+                try:
+                    f()
+                except BaseException:
+                    pass
+            _testcapi.remove_mem_hooks()
+        """
+        rc, out, err = script_helper.assert_python_ok("-c", code)
+        self.assertEqual(rc, 0)
+        self.assertFalse(out, msg=out.decode('utf-8'))
+        self.assertFalse(err, msg=err.decode('utf-8'))
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-07-03-22-32-58.gh-issue-152083.nSAuhO.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-07-03-22-32-58.gh-issue-152083.nSAuhO.rst
new file mode 100644
index 000000000000000..b8d3149f7a5cd98
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-07-03-22-32-58.gh-issue-152083.nSAuhO.rst
@@ -0,0 +1,2 @@
+Fix a crash when an object's managed dictionary is cleared under low memory
+while an exception is set.
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 6029205eac8b20f..eb559fdc6b373ef 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -7944,6 +7944,9 @@ PyObject_ClearManagedDict(PyObject *obj)
             // values. We need to materialize the keys. Nothing can modify
             // this object, but we need to lock the dictionary.
             int err;
+            // gh-152083: an exception may already be set, so keep it.
+            // The OOM path below reports via PyErr_FormatUnraisable() which clears it.
+            PyObject *exc = PyErr_GetRaisedException();
             Py_BEGIN_CRITICAL_SECTION(dict);
             err = detach_dict_from_object(dict, obj);
             Py_END_CRITICAL_SECTION();
@@ -7963,6 +7966,7 @@ PyObject_ClearManagedDict(PyObject *obj)
                 clear_inline_values(_PyObject_InlineValues(obj));
                 Py_END_CRITICAL_SECTION();
             }
+            PyErr_SetRaisedException(exc);
         }
     }
     Py_CLEAR(_PyObject_ManagedDictPointer(obj)->dict);

From a3d2714b0fbf84e2f7d259a13c3ae45f715f8420 Mon Sep 17 00:00:00 2001
From: Timofey Ivankov <playboicartina@gmail.com>
Date: Sun, 13 Sep 2026 14:25:27 +0300
Subject: [PATCH 2/2] rewrite test to @isolation.runInSubprocess()

---
 Lib/test/test_class.py | 48 +++++++++++++++++++-----------------------
 1 file changed, 22 insertions(+), 26 deletions(-)

diff --git a/Lib/test/test_class.py b/Lib/test/test_class.py
index 7ba009e6f41bb4f..bd7b78b188ed9a4 100644
--- a/Lib/test/test_class.py
+++ b/Lib/test/test_class.py
@@ -1113,34 +1113,30 @@ def test_prepare_preserves_order(self):
 
 
     @support.nomemtest
+    @isolation.runInSubprocess()
     def test_clear_managed_dict_no_memory_keeps_exception(self):
         # gh-152083: an exception may already be set when the managed dict is
-        # cleared under low memory. PyErr_FormatUnraisable() must not clear it.
-        code = """if 1:
-            import _testcapi
-
-            class A:
-                def __init__(self):
-                    self.a = 1
-                    self.b = 2
-
-            def f():
-                a = A()
-                a.__dict__
-                return [None] * 1000
-
-            for start in range(120):
-                _testcapi.set_nomemory(start)
-                try:
-                    f()
-                except BaseException:
-                    pass
-            _testcapi.remove_mem_hooks()
-        """
-        rc, out, err = script_helper.assert_python_ok("-c", code)
-        self.assertEqual(rc, 0)
-        self.assertFalse(out, msg=out.decode('utf-8'))
-        self.assertFalse(err, msg=err.decode('utf-8'))
+        # cleared under low memory.  PyErr_FormatUnraisable() must not clear it.
+        import _testcapi
+
+        class A:
+            def __init__(self):
+                self.a = 1
+                self.b = 2
+
+        def f():
+            a = A()
+            a.__dict__
+            return [None] * 1000
+
+        for start in range(120):
+            _testcapi.set_nomemory(start)
+            try:
+                f()
+            except BaseException:
+                pass
+        _testcapi.remove_mem_hooks()
+
 
 if __name__ == '__main__':
     unittest.main()