From ad5079b197d69195561723f68b57c8ae45762316 Mon Sep 17 00:00:00 2001
From: cocolato <haiizhu@outlook.com>
Date: Thu, 10 Sep 2026 16:08:37 +0800
Subject: [PATCH 1/3] fix jit in sub interpreter

---
 Lib/test/test_perf_profiler.py | 21 +++++++++++++++++++++
 Python/sysmodule.c             |  4 +++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_perf_profiler.py b/Lib/test/test_perf_profiler.py
index 425c76dd01ed7c2..a2e67726e959590 100644
--- a/Lib/test/test_perf_profiler.py
+++ b/Lib/test/test_perf_profiler.py
@@ -318,6 +318,27 @@ def test_sys_api_with_existing_perf_jit_trampoline(self):
                 """
         assert_python_ok("-c", code, PYTHON_JIT="0")
 
+    @unittest.skipUnless(
+        "-D_Py_JIT" in (sysconfig.get_config_var("PY_CORE_CFLAGS") or "").split(),
+        "requires a real JIT (_Py_JIT)",
+    )
+    def test_sys_api_perf_jit_backend_in_subinterpreter(self):
+        # gh-157247: a subinterpreter must not bypass the JIT/perf exclusion.
+        code = """if 1:
+                import sys
+                from contextlib import closing
+                from concurrent import interpreters
+
+                assert sys._jit.is_enabled(), "expected the JIT to be enabled"
+
+                with closing(interpreters.create()) as interp:
+                    interp.exec(
+                        "import sys; sys.activate_stack_trampoline('perf_jit')")
+                """
+        rc, out, err = assert_python_failure("-c", code, PYTHON_JIT="1")
+        self.assertIn(
+            b"Cannot activate the perf trampoline if the JIT is active", err)
+
 
 def is_unwinding_reliable_with_frame_pointers():
     cflags = sysconfig.get_config_var("PY_CORE_CFLAGS")
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 10087c1ccaac17d..03e5ac7415beb9d 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -2348,7 +2348,9 @@ sys_activate_stack_trampoline_impl(PyObject *module, const char *backend)
 {
 #ifdef PY_HAVE_PERF_TRAMPOLINE
 #ifdef _Py_JIT
-    if (_PyInterpreterState_GET()->jit) {
+    // Perf state is process-wide, and only the main interpreter can enable
+    // the JIT. Check it even when called from a subinterpreter (gh-157247).
+    if (_PyInterpreterState_Main()->jit) {
         PyErr_SetString(PyExc_ValueError, "Cannot activate the perf trampoline if the JIT is active");
         return NULL;
     }

From 9f93874018f7766c9901fba2d622e1b16496560b Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com>
Date: Thu, 10 Sep 2026 08:21:09 +0000
Subject: [PATCH 2/3] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20blu?=
 =?UTF-8?q?rb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../2026-09-10-08-21-07.gh-issue-157247.Zv4bz2.rst               | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2026-09-10-08-21-07.gh-issue-157247.Zv4bz2.rst

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-09-10-08-21-07.gh-issue-157247.Zv4bz2.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-09-10-08-21-07.gh-issue-157247.Zv4bz2.rst
new file mode 100644
index 000000000000000..226da9b17538968
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-09-10-08-21-07.gh-issue-157247.Zv4bz2.rst
@@ -0,0 +1 @@
+Fix :func:sys.activate_stack_trampoline allowing activation from a subinterpreter while the JIT is enabled in the main interpreter.

From c7bdfdd762e1c9aa686caa23c11325ebf4d65bb3 Mon Sep 17 00:00:00 2001
From: cocolato <haiizhu@outlook.com>
Date: Thu, 10 Sep 2026 16:24:13 +0800
Subject: [PATCH 3/3] fix lint

---
 .../2026-09-10-08-21-07.gh-issue-157247.Zv4bz2.rst             | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-09-10-08-21-07.gh-issue-157247.Zv4bz2.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-09-10-08-21-07.gh-issue-157247.Zv4bz2.rst
index 226da9b17538968..005132576a134bd 100644
--- a/Misc/NEWS.d/next/Core_and_Builtins/2026-09-10-08-21-07.gh-issue-157247.Zv4bz2.rst
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-09-10-08-21-07.gh-issue-157247.Zv4bz2.rst
@@ -1 +1,2 @@
-Fix :func:sys.activate_stack_trampoline allowing activation from a subinterpreter while the JIT is enabled in the main interpreter.
+Fix :func:`sys.activate_stack_trampoline` allowing activation from a
+subinterpreter while the JIT is enabled in the main interpreter.