Prevent unloading methods used in root_fiber while calling another Fiber (#2939)

Fixing SEGVs like:
http://ci.rvm.jp/results/trunk-mjit-wait@silicon-docker/2744905
http://ci.rvm.jp/results/trunk-mjit-wait@silicon-docker/2744420
http://ci.rvm.jp/results/trunk-mjit-wait@silicon-docker/2741400
[Bug #16664]

(cherry picked from commit adcf0316d1ecedae2a9157ad941550e0c0fb510b)

1 files changed, 3 insertions, 0 deletions

diff --git a/mjit.c b/mjit.c
index df0169e748..4dc6ad80b4 100644
--- a/mjit.c
+++ b/mjit.c
@@ -801,6 +801,9 @@ mjit_init(const struct mjit_options *opts)
     rb_native_cond_initialize(&mjit_worker_wakeup);
     rb_native_cond_initialize(&mjit_gc_wakeup);
 
+    // Make sure root_fiber's saved_ec is scanned by mark_ec_units
+    rb_fiber_init_mjit_cont(GET_EC()->fiber_ptr);
+
     // Initialize class_serials cache for compilation
     valid_class_serials = rb_hash_new();
     rb_obj_hide(valid_class_serials);