1 files changed, 18 insertions, 2 deletions

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 7ff682770fdb..f1a4c833121e 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1387,6 +1387,24 @@ int machine__process_fork_event(struct machine *machine, union perf_event *event
                                                         event->fork.ptid);
         int err = 0;
 
+        if (dump_trace)
+                perf_event__fprintf_task(event, stdout);
+
+        /*
+         * There may be an existing thread that is not actually the parent,
+         * either because we are processing events out of order, or because the
+         * (fork) event that would have removed the thread was lost. Assume the
+         * latter case and continue on as best we can.
+         */
+        if (parent->pid_ != (pid_t)event->fork.ppid) {
+                dump_printf("removing erroneous parent thread %d/%d\n",
+                            parent->pid_, parent->tid);
+                machine__remove_thread(machine, parent);
+                thread__put(parent);
+                parent = machine__findnew_thread(machine, event->fork.ppid,
+                                                 event->fork.ptid);
+        }
+
         /* if a thread currently exists for the thread id remove it */
         if (thread != NULL) {
                 machine__remove_thread(machine, thread);
@@ -1395,8 +1413,6 @@ int machine__process_fork_event(struct machine *machine, union perf_event *event
 
         thread = machine__findnew_thread(machine, event->fork.pid,
                                          event->fork.tid);
-        if (dump_trace)
-                perf_event__fprintf_task(event, stdout);
 
         if (thread == NULL || parent == NULL ||
             thread__fork(thread, parent, sample->time) < 0) {