Return only from the frame profiled

pablogsal · pablogsal · commit c5307fb62a9f · 2025-12-02T03:40:52.000Z
diff --git a/Python/ceval.c b/Python/ceval.c
@@ -2006,8 +2006,11 @@ _PyEval_FrameClearAndPop(PyThreadState *tstate, _PyInterpreterFrame * frame)
 {
     // Update last_profiled_frame for remote profiler frame caching.
     // By this point, tstate->current_frame is already set to the parent frame.
-    // The guarded check avoids writes when profiling is not active (predictable branch).
-    if (tstate->last_profiled_frame != NULL) {
+    // Only update if we're popping the exact frame that was last profiled.
+    // This avoids corrupting the cache when transient frames (called and returned
+    // between profiler samples) update last_profiled_frame to addresses the
+    // profiler never saw.
+    if (tstate->last_profiled_frame != NULL && tstate->last_profiled_frame == frame) {
         tstate->last_profiled_frame = tstate->current_frame;
     }
 

Original file line number	Diff line number	Diff line change
`@@ -2006,8 +2006,11 @@ _PyEval_FrameClearAndPop(PyThreadState tstate, _PyInterpreterFrame frame)`
`2006`	`2006`	`{`
`2007`	`2007`	`// Update last_profiled_frame for remote profiler frame caching.`
`2008`	`2008`	`// By this point, tstate->current_frame is already set to the parent frame.`
`2009`		`- // The guarded check avoids writes when profiling is not active (predictable branch).`
`2010`		`- if (tstate->last_profiled_frame != NULL) {`
	`2009`	`+ // Only update if we're popping the exact frame that was last profiled.`
	`2010`	`+ // This avoids corrupting the cache when transient frames (called and returned`
	`2011`	`+ // between profiler samples) update last_profiled_frame to addresses the`
	`2012`	`+ // profiler never saw.`
	`2013`	`+ if (tstate->last_profiled_frame != NULL && tstate->last_profiled_frame == frame) {`
`2011`	`2014`	`tstate->last_profiled_frame = tstate->current_frame;`
`2012`	`2015`	`}`
`2013`	`2016`