From 44379805b0859179ed4c9fb68bb2e5e95720cc3a Mon Sep 17 00:00:00 2001
From: Peter Zhu <peter@peterzhu.ca>
Date: Tue, 4 Jan 2022 13:54:21 -0500
Subject: [PATCH] Fix crash on bootup when RGENGC_CHECK_MODE=2 with GC stress

We need to unshare the array loaded_features because the shared root
could be old gen (while loaded_features is young) which causes a WB
miss.
---
 ruby.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/ruby.c b/ruby.c
index f63cecdb98..b17c29a526 100644
--- a/ruby.c
+++ b/ruby.c
@@ -2062,7 +2062,10 @@ process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
         for (long i = loaded_before_enc; i < RARRAY_LEN(loaded_features); ++i) {
 	    VALUE path = RARRAY_AREF(loaded_features, i);
             if (!(path = copy_str(path, IF_UTF8_PATH(uenc, lenc), true))) continue;
-            modified = true;
+            if (!modified) {
+                rb_ary_modify(loaded_features);
+                modified = true;
+            }
 	    RARRAY_ASET(loaded_features, i, path);
         }
         if (modified) {