From 4eab5a0bf7b98409d5544cfbf78f6e1fae82d601 Mon Sep 17 00:00:00 2001
From: maurycy <5383+maurycy@users.noreply.github.com>
Date: Sat, 13 Jun 2026 11:42:54 +0200
Subject: [PATCH 1/2] up last_profiled_frame

---
 Modules/_testinternalcapi/test_cases.c.h | 9 +++++++++
 Objects/genobject.c                      | 6 ++++++
 Python/bytecodes.c                       | 6 ++++++
 Python/ceval.c                           | 3 +++
 Python/executor_cases.c.h                | 6 ++++++
 Python/generated_cases.c.h               | 9 +++++++++
 6 files changed, 39 insertions(+)

diff --git a/Modules/_testinternalcapi/test_cases.c.h b/Modules/_testinternalcapi/test_cases.c.h
index 503f566c9ae86a5..d3ac8e6f96b4193 100644
--- a/Modules/_testinternalcapi/test_cases.c.h
+++ b/Modules/_testinternalcapi/test_cases.c.h
@@ -7939,6 +7939,9 @@
                 gen->gi_exc_state.previous_item = NULL;
                 _Py_LeaveRecursiveCallPy(tstate);
                 _PyInterpreterFrame *gen_frame = frame;
+                if (tstate->last_profiled_frame == gen_frame) {
+                    tstate->last_profiled_frame = gen_frame->previous;
+                }
                 frame = tstate->current_frame = frame->previous;
                 gen_frame->previous = NULL;
                 ((_PyThreadStateImpl *)tstate)->generator_return_kind = GENERATOR_YIELD;
@@ -11000,6 +11003,9 @@
             gen_frame->owner = FRAME_OWNED_BY_GENERATOR;
             _Py_LeaveRecursiveCallPy(tstate);
             _PyInterpreterFrame *prev = frame->previous;
+            if (tstate->last_profiled_frame == frame) {
+                tstate->last_profiled_frame = prev;
+            }
             _PyThreadState_PopFrame(tstate, frame);
             frame = tstate->current_frame = prev;
             LOAD_IP(frame->return_offset);
@@ -13029,6 +13035,9 @@
                 gen->gi_exc_state.previous_item = NULL;
                 _Py_LeaveRecursiveCallPy(tstate);
                 _PyInterpreterFrame *gen_frame = frame;
+                if (tstate->last_profiled_frame == gen_frame) {
+                    tstate->last_profiled_frame = gen_frame->previous;
+                }
                 frame = tstate->current_frame = frame->previous;
                 gen_frame->previous = NULL;
                 ((_PyThreadStateImpl *)tstate)->generator_return_kind = GENERATOR_YIELD;
diff --git a/Objects/genobject.c b/Objects/genobject.c
index 38d493343454fce..68249fc9a6a77de 100644
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -681,6 +681,9 @@ _gen_throw(PyGenObject *gen, int close_on_genexit,
                'yield from' or awaiting on with 'await'. */
             ret = _gen_throw((PyGenObject *)yf, close_on_genexit,
                              typ, val, tb);
+            if (tstate->last_profiled_frame == frame) {
+                tstate->last_profiled_frame = prev;
+            }
             tstate->current_frame = prev;
             frame->previous = NULL;
         }
@@ -701,6 +704,9 @@ _gen_throw(PyGenObject *gen, int close_on_genexit,
             frame->previous = prev;
             tstate->current_frame = frame;
             ret = PyObject_CallFunctionObjArgs(meth, typ, val, tb, NULL);
+            if (tstate->last_profiled_frame == frame) {
+                tstate->last_profiled_frame = prev;
+            }
             tstate->current_frame = prev;
             frame->previous = NULL;
             Py_DECREF(meth);
diff --git a/Python/bytecodes.c b/Python/bytecodes.c
index e368092b300f864..08c09edd0e7a0a5 100644
--- a/Python/bytecodes.c
+++ b/Python/bytecodes.c
@@ -1860,6 +1860,9 @@ dummy_func(
             gen->gi_exc_state.previous_item = NULL;
             _Py_LeaveRecursiveCallPy(tstate);
             _PyInterpreterFrame *gen_frame = frame;
+            if (tstate->last_profiled_frame == gen_frame) {
+                tstate->last_profiled_frame = gen_frame->previous;
+            }
             frame = tstate->current_frame = frame->previous;
             gen_frame->previous = NULL;
             ((_PyThreadStateImpl *)tstate)->generator_return_kind = GENERATOR_YIELD;
@@ -5874,6 +5877,9 @@ dummy_func(
             gen_frame->owner = FRAME_OWNED_BY_GENERATOR;
             _Py_LeaveRecursiveCallPy(tstate);
             _PyInterpreterFrame *prev = frame->previous;
+            if (tstate->last_profiled_frame == frame) {
+                tstate->last_profiled_frame = prev;
+            }
             _PyThreadState_PopFrame(tstate, frame);
             frame = tstate->current_frame = prev;
             LOAD_IP(frame->return_offset);
diff --git a/Python/ceval.c b/Python/ceval.c
index a9b31affca9890a..b7d8afa1b122f22 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -2006,6 +2006,9 @@ _PyEvalFramePushAndInit(PyThreadState *tstate, _PyStackRef func,
     _PyFrame_Initialize(tstate, frame, func, locals, code, 0, previous);
     if (initialize_locals(tstate, func_obj, frame->localsplus, args, argcount, kwnames)) {
         assert(frame->owner == FRAME_OWNED_BY_THREAD);
+        if (tstate->last_profiled_frame == frame) {
+            tstate->last_profiled_frame = tstate->current_frame;
+        }
         clear_thread_frame(tstate, frame);
         return NULL;
     }
diff --git a/Python/executor_cases.c.h b/Python/executor_cases.c.h
index 7973c75e1a60ad2..0589b860716c2e7 100644
--- a/Python/executor_cases.c.h
+++ b/Python/executor_cases.c.h
@@ -9340,6 +9340,9 @@
             gen->gi_exc_state.previous_item = NULL;
             _Py_LeaveRecursiveCallPy(tstate);
             _PyInterpreterFrame *gen_frame = frame;
+            if (tstate->last_profiled_frame == gen_frame) {
+                tstate->last_profiled_frame = gen_frame->previous;
+            }
             frame = tstate->current_frame = frame->previous;
             gen_frame->previous = NULL;
             ((_PyThreadStateImpl *)tstate)->generator_return_kind = GENERATOR_YIELD;
@@ -20346,6 +20349,9 @@
             gen_frame->owner = FRAME_OWNED_BY_GENERATOR;
             _Py_LeaveRecursiveCallPy(tstate);
             _PyInterpreterFrame *prev = frame->previous;
+            if (tstate->last_profiled_frame == frame) {
+                tstate->last_profiled_frame = prev;
+            }
             _PyThreadState_PopFrame(tstate, frame);
             frame = tstate->current_frame = prev;
             LOAD_IP(frame->return_offset);
diff --git a/Python/generated_cases.c.h b/Python/generated_cases.c.h
index 5adcdcb4521baf5..3a7265ecbe31f41 100644
--- a/Python/generated_cases.c.h
+++ b/Python/generated_cases.c.h
@@ -7938,6 +7938,9 @@
                 gen->gi_exc_state.previous_item = NULL;
                 _Py_LeaveRecursiveCallPy(tstate);
                 _PyInterpreterFrame *gen_frame = frame;
+                if (tstate->last_profiled_frame == gen_frame) {
+                    tstate->last_profiled_frame = gen_frame->previous;
+                }
                 frame = tstate->current_frame = frame->previous;
                 gen_frame->previous = NULL;
                 ((_PyThreadStateImpl *)tstate)->generator_return_kind = GENERATOR_YIELD;
@@ -10997,6 +11000,9 @@
             gen_frame->owner = FRAME_OWNED_BY_GENERATOR;
             _Py_LeaveRecursiveCallPy(tstate);
             _PyInterpreterFrame *prev = frame->previous;
+            if (tstate->last_profiled_frame == frame) {
+                tstate->last_profiled_frame = prev;
+            }
             _PyThreadState_PopFrame(tstate, frame);
             frame = tstate->current_frame = prev;
             LOAD_IP(frame->return_offset);
@@ -13026,6 +13032,9 @@
                 gen->gi_exc_state.previous_item = NULL;
                 _Py_LeaveRecursiveCallPy(tstate);
                 _PyInterpreterFrame *gen_frame = frame;
+                if (tstate->last_profiled_frame == gen_frame) {
+                    tstate->last_profiled_frame = gen_frame->previous;
+                }
                 frame = tstate->current_frame = frame->previous;
                 gen_frame->previous = NULL;
                 ((_PyThreadStateImpl *)tstate)->generator_return_kind = GENERATOR_YIELD;

From 4c946536e9ba30767d36410d0527b0dc055071d9 Mon Sep 17 00:00:00 2001
From: maurycy <5383+maurycy@users.noreply.github.com>
Date: Sat, 13 Jun 2026 11:58:17 +0200
Subject: [PATCH 2/2] news

---
 .../Library/2026-06-13-11-57-48.gh-issue-151436.UEDowO.rst    | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2026-06-13-11-57-48.gh-issue-151436.UEDowO.rst

diff --git a/Misc/NEWS.d/next/Library/2026-06-13-11-57-48.gh-issue-151436.UEDowO.rst b/Misc/NEWS.d/next/Library/2026-06-13-11-57-48.gh-issue-151436.UEDowO.rst
new file mode 100644
index 000000000000000..1d1aadbf57be485
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-06-13-11-57-48.gh-issue-151436.UEDowO.rst
@@ -0,0 +1,4 @@
+Fix skewed stack trackes in the Tachyon profiler when caching is enabled and
+when generators and coroutines are profiled, by updating
+``tstate->last_profiled_frame`` at every frame-removal site. The issue resulted
+in total erasure of some callers. Patch by Maurycy Pawłowski-Wieroński.