block_for_vivify_loop.patch

diff --git a/src/io/eventloop.c b/src/io/eventloop.c
index 06e7e9e..29563fb 100644
--- a/src/io/eventloop.c
+++ b/src/io/eventloop.c
@@ -72,7 +72,9 @@ static uv_loop_t *get_or_vivify_loop(MVMThreadContext *tc) {
 
     if (!instance->event_loop_thread) {
         /* Grab starting mutex and ensure we didn't lose the race. */
+        MVM_gc_mark_thread_blocked(tc);
         uv_mutex_lock(&instance->mutex_event_loop_start);
+        MVM_gc_mark_thread_unblocked(tc);
         if (!instance->event_loop_thread) {
             MVMObject *thread, *loop_runner;
             int r;