Log task goroutine IDs in the sentry watchdog.

PiperOrigin-RevId: 342373580

pkg/sentry/kernel/task_run.go

@@ -390,6 +390,11 @@ func (t *Task) assertTaskGoroutine() {
 	}
 }
 
+// GoroutineID returns the ID of t's task goroutine.
+func (t *Task) GoroutineID() int64 {
+	return atomic.LoadInt64(&t.goid)
+}
+
 // waitGoroutineStoppedOrExited blocks until t's task goroutine stops or exits.
 func (t *Task) waitGoroutineStoppedOrExited() {
 	t.goroutineStopped.Wait()

pkg/sentry/watchdog/watchdog.go

@@ -336,11 +336,9 @@ func (w *Watchdog) report(offenders map[*kernel.Task]*offender, newTaskFound boo
 	buf.WriteString(fmt.Sprintf("Sentry detected %d stuck task(s):\n", len(offenders)))
 	for t, o := range offenders {
 		tid := w.k.TaskSet().Root.IDOfTask(t)
-		buf.WriteString(fmt.Sprintf("\tTask tid: %v (%#x), entered RunSys state %v ago.\n", tid, uint64(tid), now.Sub(o.lastUpdateTime)))
+		buf.WriteString(fmt.Sprintf("\tTask tid: %v (goroutine %d), entered RunSys state %v ago.\n", tid, t.GoroutineID(), now.Sub(o.lastUpdateTime)))
 	}
 
-	buf.WriteString("Search for '(*Task).run(0x..., 0x<tid>)' in the stack dump to find the offending goroutine")
-
 	// Force stack dump only if a new task is detected.
 	w.doAction(w.TaskTimeoutAction, newTaskFound, &buf)
 }