https://github.com/python/cpython/commit/4c9f2675ba13274526d2ae0d467aa05ca48b2971
commit: 4c9f2675ba13274526d2ae0d467aa05ca48b2971
branch: main
author: Hai Zhu <[email protected]>
committer: kumaraditya303 <[email protected]>
date: 2026-09-11T19:07:26+05:30
summary:
gh-157247: Block perf trampoline activation when the main interpreter's JIT is
enabled (#157258)
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2026-09-10-08-21-07.gh-issue-157247.Zv4bz2.rst
M Lib/test/test_perf_profiler.py
M Python/sysmodule.c
diff --git a/Lib/test/test_perf_profiler.py b/Lib/test/test_perf_profiler.py
index 425c76dd01ed7c..a2e67726e95959 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/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 00000000000000..005132576a134b
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2026-09-10-08-21-07.gh-issue-157247.Zv4bz2.rst
@@ -0,0 +1,2 @@
+Fix :func:`sys.activate_stack_trampoline` allowing activation from a
+subinterpreter while the JIT is enabled in the main interpreter.
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 10087c1ccaac17..03e5ac7415beb9 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;
}
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