4 files changed, 155 insertions, 2 deletions
diff --git a/src/runtime/cgocall.go b/src/runtime/cgocall.go
index 326674cd2e..b046ab960f 100644
--- a/src/runtime/cgocall.go
+++ b/src/runtime/cgocall.go
@@ -355,7 +355,9 @@ func cgocallbackg(fn, frame unsafe.Pointer, ctxt uintptr) {
 	gp.m.incgo = true
 	unlockOSThread()
 
-	if gp.m.isextra {
+	if gp.m.isextra && gp.m.ncgo == 0 {
+		// There are no active cgocalls above this frame (ncgo == 0),
+		// thus there can't be more Go frames above this frame.
 		gp.m.isExtraInC = true
 	}
 
diff --git a/src/runtime/crash_cgo_test.go b/src/runtime/crash_cgo_test.go
index e9b449ab88..a7321f49a5 100644
--- a/src/runtime/crash_cgo_test.go
+++ b/src/runtime/crash_cgo_test.go
@@ -72,6 +72,19 @@ func TestCgoCallbackGC(t *testing.T) {
 	}
 }
 
+func TestCgoCallbackPprof(t *testing.T) {
+	t.Parallel()
+	switch runtime.GOOS {
+	case "plan9", "windows":
+		t.Skipf("no pthreads on %s", runtime.GOOS)
+	}
+
+	got := runTestProg(t, "testprogcgo", "CgoCallbackPprof")
+	if want := "OK\n"; got != want {
+		t.Fatalf("expected %q, but got:\n%s", want, got)
+	}
+}
+
 func TestCgoExternalThreadPanic(t *testing.T) {
 	t.Parallel()
 	if runtime.GOOS == "plan9" {
diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go
index 0c70d2cc81..6b9f49d503 100644
--- a/src/runtime/runtime2.go
+++ b/src/runtime/runtime2.go
@@ -554,7 +554,7 @@ type m struct {
 	printlock       int8
 	incgo           bool          // m is executing a cgo call
 	isextra         bool          // m is an extra m
-	isExtraInC      bool          // m is an extra m that is not executing Go code
+	isExtraInC      bool          // m is an extra m that does not have any Go frames
 	isExtraInSig    bool          // m is an extra m in a signal handler
 	freeWait        atomic.Uint32 // Whether it is safe to free g0 and delete m (one of freeMRef, freeMStack, freeMWait)
 	needextram      bool
diff --git a/src/runtime/testdata/testprogcgo/callback_pprof.go b/src/runtime/testdata/testprogcgo/callback_pprof.go
new file mode 100644
index 0000000000..cd235d0341
--- /dev/null
+++ b/src/runtime/testdata/testprogcgo/callback_pprof.go
@@ -0,0 +1,138 @@
+// Copyright 2025 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !plan9 && !windows
+
+package main
+
+// Regression test for https://go.dev/issue/72870. Go code called from C should
+// never be reported as external code.
+
+/*
+#include <pthread.h>
+
+void go_callback1();
+void go_callback2();
+
+static void *callback_pprof_thread(void *arg) {
+    go_callback1();
+    return 0;
+}
+
+static void c_callback(void) {
+    go_callback2();
+}
+
+static void start_callback_pprof_thread() {
+    pthread_t th;
+    pthread_attr_t attr;
+    pthread_attr_init(&attr);
+    pthread_create(&th, &attr, callback_pprof_thread, 0);
+    // Don't join, caller will watch pprof.
+}
+*/
+import "C"
+
+import (
+	"bytes"
+	"fmt"
+	"internal/profile"
+	"os"
+	"runtime/pprof"
+	"time"
+)
+
+func init() {
+	register("CgoCallbackPprof", CgoCallbackPprof)
+}
+
+func CgoCallbackPprof() {
+	C.start_callback_pprof_thread()
+
+	var buf bytes.Buffer
+	if err := pprof.StartCPUProfile(&buf); err != nil {
+		fmt.Printf("Error starting CPU profile: %v\n", err)
+		os.Exit(1)
+	}
+	time.Sleep(1 * time.Second)
+	pprof.StopCPUProfile()
+
+	p, err := profile.Parse(&buf)
+	if err != nil {
+		fmt.Printf("Error parsing profile: %v\n", err)
+		os.Exit(1)
+	}
+
+	foundCallee := false
+	for _, s := range p.Sample {
+		funcs := flattenFrames(s)
+		if len(funcs) == 0 {
+			continue
+		}
+
+		leaf := funcs[0]
+		if leaf.Name != "main.go_callback1_callee" {
+			continue
+		}
+		foundCallee = true
+
+		if len(funcs) < 2 {
+			fmt.Printf("Profile: %s\n", p)
+			frames := make([]string, len(funcs))
+			for i := range funcs {
+				frames[i] = funcs[i].Name
+			}
+			fmt.Printf("FAIL: main.go_callback1_callee sample missing caller in frames %v\n", frames)
+			os.Exit(1)
+		}
+
+		if funcs[1].Name != "main.go_callback1" {
+			// In https://go.dev/issue/72870, this will be runtime._ExternalCode.
+			fmt.Printf("Profile: %s\n", p)
+			frames := make([]string, len(funcs))
+			for i := range funcs {
+				frames[i] = funcs[i].Name
+			}
+			fmt.Printf("FAIL: main.go_callback1_callee sample caller got %s want main.go_callback1 in frames %v\n", funcs[1].Name, frames)
+			os.Exit(1)
+		}
+	}
+
+	if !foundCallee {
+		fmt.Printf("Missing main.go_callback1_callee sample in profile %s\n", p)
+		os.Exit(1)
+	}
+
+	fmt.Printf("OK\n")
+}
+
+// Return the frame functions in s, regardless of inlining.
+func flattenFrames(s *profile.Sample) []*profile.Function {
+	ret := make([]*profile.Function, 0, len(s.Location))
+	for _, loc := range s.Location {
+		for _, line := range loc.Line {
+			ret = append(ret, line.Function)
+		}
+	}
+	return ret
+}
+
+//export go_callback1
+func go_callback1() {
+	// This is a separate function just to ensure we have another Go
+	// function as the caller in the profile.
+	go_callback1_callee()
+}
+
+func go_callback1_callee() {
+	C.c_callback()
+
+	// Spin for CPU samples.
+	for {
+	}
+}
+
+//export go_callback2
+func go_callback2() {
+}