gh-158443: Fix asyncio ps showing a running task as a single frame

Lib/test/test_external_inspection.py

@@ -458,6 +458,25 @@ async def main():
         self.assertIn(main_name, names)
         self.assertEqual([len(n) for n in names if n.startswith("x")], [255])
 
+    @skip_if_not_supported
+    def test_running_task_reports_its_call_stack(self):
+        # gh-158443
+        async def inner():
+            return [
+                [frame.funcname.rpartition(".")[2] for frame in coro.call_stack]
+                for info in RemoteUnwinder(os.getpid()).get_all_awaited_by()
+                for task in info.awaited_by
+                for coro in task.coroutine_stack
+            ]
+
+        async def middle():
+            return await inner()
+
+        async def main():
+            return await middle()
+
+        self.assertEqual(asyncio.run(main()), [["inner", "middle", "main"]])
+
     @skip_if_not_supported
     @unittest.skipIf(
         sys.platform == "linux" and not PROCESS_VM_READV_SUPPORTED,

Misc/NEWS.d/next/Library/2026-09-29-20-34-53.gh-issue-158443.-1rc7t.rst

@@ -0,0 +1,2 @@
+Fix ``python -m asyncio ps`` showing a task that is running as a single
+frame instead of its call stack. Patch by Timofei Ivankov.

Modules/_remote_debugging/_remote_debugging.h

@@ -402,6 +402,8 @@ typedef struct {
     pid_t *thread_tids;           // Reusable buffer for thread IDs
     size_t thread_tids_capacity;  // Current capacity of thread_tids buffer
 #endif
+    // Thread whose task list is being walked, 0 when there is none
+    uintptr_t walked_thread_addr;
 } RemoteUnwinderObject;
 
 #define RemoteUnwinder_CAST(op) ((RemoteUnwinderObject *)(op))

Modules/_remote_debugging/asyncio.c

@@ -363,6 +363,17 @@ parse_coro_chain(
         return 0;
     }
 
+    if (frame_state == FRAME_EXECUTING && unwinder->walked_thread_addr) {
+        // gh-158443: a running coroutine keeps its inner frames on the thread stack
+        Py_DECREF(name);
+        if (parse_async_frame_chain(unwinder, render_to,
+                                    unwinder->walked_thread_addr,
+                                    address_of_code_object) < 0) {
+            return -1;
+        }
+        return PyList_Reverse(render_to);
+    }
+
     if (PyList_Append(render_to, name)) {
         Py_DECREF(name);
         set_exception_cause(unwinder, PyExc_RuntimeError, "Failed to append frame to coro chain");
@@ -930,7 +941,11 @@ process_thread_for_awaited_by(
 ) {
     PyObject *result = (PyObject *)context;
     uintptr_t head_addr = thread_state_addr + (uintptr_t)unwinder->async_debug_offsets.asyncio_thread_state.asyncio_tasks_head;
-    return append_awaited_by(unwinder, tid, head_addr, result);
+
+    unwinder->walked_thread_addr = thread_state_addr;
+    int res = append_awaited_by(unwinder, tid, head_addr, result);
+    unwinder->walked_thread_addr = 0;
+    return res;
 }
 
 static int