diff --git a/NEWS.md b/NEWS.md
index 6f20061a27882c..df71bf98e898df 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -26,6 +26,11 @@ Note: We're only listing outstanding class updates.
       directory without hardcoding absolute paths or manipulating `$LOAD_PATH`.
       [[Feature #15330]]
 
+* MatchData
+
+    * `MatchData#integer_at` is added.  It converts the matched substring to
+      integer and return the result.  [[Feature #21932]]
+
 * Method
 
     * `Method#source_location`, `Proc#source_location`, and
@@ -130,6 +135,7 @@ A lot of work has gone into making Ractors more stable, performant, and usable.
 [Feature #15330]: https://bugs.ruby-lang.org/issues/15330
 [Feature #21390]: https://bugs.ruby-lang.org/issues/21390
 [Feature #21785]: https://bugs.ruby-lang.org/issues/21785
+[Feature #21932]: https://bugs.ruby-lang.org/issues/21932
 [test-unit-3.7.4]: https://github.com/test-unit/test-unit/releases/tag/3.7.4
 [test-unit-3.7.5]: https://github.com/test-unit/test-unit/releases/tag/3.7.5
 [rss-0.3.2]: https://github.com/ruby/rss/releases/tag/0.3.2
diff --git a/ext/json/generator/extconf.rb b/ext/json/generator/extconf.rb
index ee1bbeaba76346..205a887e78f3bd 100644
--- a/ext/json/generator/extconf.rb
+++ b/ext/json/generator/extconf.rb
@@ -5,6 +5,8 @@
   File.write('Makefile', dummy_makefile("").join)
 else
   append_cflags("-std=c99")
+  have_const("RUBY_TYPED_EMBEDDABLE", "ruby.h") # RUBY_VERSION >= 3.3
+
   $defs << "-DJSON_GENERATOR"
   $defs << "-DJSON_DEBUG" if ENV.fetch("JSON_DEBUG", "0") != "0"
 
diff --git a/ext/json/generator/generator.c b/ext/json/generator/generator.c
index a6302691d9fd6b..b52bc975124aa9 100644
--- a/ext/json/generator/generator.c
+++ b/ext/json/generator/generator.c
@@ -722,27 +722,20 @@ static void State_compact(void *ptr)
     state->as_json = rb_gc_location(state->as_json);
 }
 
-static void State_free(void *ptr)
-{
-    JSON_Generator_State *state = ptr;
-    ruby_xfree(state);
-}
-
 static size_t State_memsize(const void *ptr)
 {
     return sizeof(JSON_Generator_State);
 }
 
 static const rb_data_type_t JSON_Generator_State_type = {
-    "JSON/Generator/State",
-    {
+    .wrap_struct_name = "JSON/Generator/State",
+    .function = {
         .dmark = State_mark,
-        .dfree = State_free,
+        .dfree = RUBY_DEFAULT_FREE,
         .dsize = State_memsize,
         .dcompact = State_compact,
     },
-    0, 0,
-    RUBY_TYPED_WB_PROTECTED | RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_FROZEN_SHAREABLE,
+    .flags = RUBY_TYPED_WB_PROTECTED | RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_FROZEN_SHAREABLE | RUBY_TYPED_EMBEDDABLE,
 };
 
 static void state_init(JSON_Generator_State *state)
diff --git a/ext/json/json.h b/ext/json/json.h
index 087a2eae66e317..8737989a6c9aa6 100644
--- a/ext/json/json.h
+++ b/ext/json/json.h
@@ -54,6 +54,17 @@ typedef unsigned char _Bool;
 #   define RUBY_TYPED_FROZEN_SHAREABLE 0
 #endif
 
+#ifdef RUBY_TYPED_EMBEDDABLE
+#  define HAVE_RUBY_TYPED_EMBEDDABLE 1
+#else
+# ifdef HAVE_CONST_RUBY_TYPED_EMBEDDABLE
+#  define RUBY_TYPED_EMBEDDABLE RUBY_TYPED_EMBEDDABLE
+#  define HAVE_RUBY_TYPED_EMBEDDABLE 1
+# else
+#  define RUBY_TYPED_EMBEDDABLE 0
+# endif
+#endif
+
 #ifndef NORETURN
 #if defined(__has_attribute) && __has_attribute(noreturn)
 #define NORETURN(x) __attribute__((noreturn)) x
diff --git a/ext/json/parser/extconf.rb b/ext/json/parser/extconf.rb
index 2440e66d8bdb39..f12fc2dddce02a 100644
--- a/ext/json/parser/extconf.rb
+++ b/ext/json/parser/extconf.rb
@@ -7,6 +7,10 @@
 have_func("rb_hash_new_capa", "ruby.h") # RUBY_VERSION >= 3.2
 have_func("rb_hash_bulk_insert", "ruby.h") # Missing on TruffleRuby
 
+if RUBY_ENGINE == "ruby"
+  have_const("RUBY_TYPED_EMBEDDABLE", "ruby.h") # RUBY_VERSION >= 3.3
+end
+
 append_cflags("-std=c99")
 
 if enable_config('parser-use-simd', default=!ENV["JSON_DISABLE_SIMD"])
diff --git a/ext/json/parser/parser.c b/ext/json/parser/parser.c
index 1a8e2aaf485b62..b05f3f5273d71d 100644
--- a/ext/json/parser/parser.c
+++ b/ext/json/parser/parser.c
@@ -241,17 +241,27 @@ static void rvalue_stack_mark(void *ptr)
 {
     rvalue_stack *stack = (rvalue_stack *)ptr;
     long index;
-    for (index = 0; index < stack->head; index++) {
-        rb_gc_mark(stack->ptr[index]);
+    if (stack && stack->ptr) {
+        for (index = 0; index < stack->head; index++) {
+            rb_gc_mark(stack->ptr[index]);
+        }
     }
 }
 
+static void rvalue_stack_free_buffer(rvalue_stack *stack)
+{
+    ruby_xfree(stack->ptr);
+    stack->ptr = NULL;
+}
+
 static void rvalue_stack_free(void *ptr)
 {
     rvalue_stack *stack = (rvalue_stack *)ptr;
     if (stack) {
-        ruby_xfree(stack->ptr);
+        rvalue_stack_free_buffer(stack);
+#ifndef HAVE_RUBY_TYPED_EMBEDDABLE
         ruby_xfree(stack);
+#endif
     }
 }
 
@@ -262,14 +272,13 @@ static size_t rvalue_stack_memsize(const void *ptr)
 }
 
 static const rb_data_type_t JSON_Parser_rvalue_stack_type = {
-    "JSON::Ext::Parser/rvalue_stack",
-    {
+    .wrap_struct_name = "JSON::Ext::Parser/rvalue_stack",
+    .function = {
         .dmark = rvalue_stack_mark,
         .dfree = rvalue_stack_free,
         .dsize = rvalue_stack_memsize,
     },
-    0, 0,
-    RUBY_TYPED_FREE_IMMEDIATELY,
+    .flags = RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_EMBEDDABLE,
 };
 
 static rvalue_stack *rvalue_stack_spill(rvalue_stack *old_stack, VALUE *handle, rvalue_stack **stack_ref)
@@ -291,8 +300,12 @@ static void rvalue_stack_eagerly_release(VALUE handle)
     if (handle) {
         rvalue_stack *stack;
         TypedData_Get_Struct(handle, rvalue_stack, &JSON_Parser_rvalue_stack_type, stack);
-        RTYPEDDATA_DATA(handle) = NULL;
+#ifdef HAVE_RUBY_TYPED_EMBEDDABLE
+        rvalue_stack_free_buffer(stack);
+#else
         rvalue_stack_free(stack);
+        RTYPEDDATA_DATA(handle) = NULL;
+#endif
     }
 }
 
@@ -343,7 +356,7 @@ typedef struct JSON_ParserStruct {
 } JSON_ParserConfig;
 
 typedef struct JSON_ParserStateStruct {
-    VALUE stack_handle;
+    VALUE *stack_handle;
     const char *start;
     const char *cursor;
     const char *end;
@@ -944,7 +957,7 @@ static inline VALUE json_push_value(JSON_ParserState *state, JSON_ParserConfig *
     if (RB_UNLIKELY(config->on_load_proc)) {
         value = rb_proc_call_with_block(config->on_load_proc, 1, &value, Qnil);
     }
-    rvalue_stack_push(state->stack, value, &state->stack_handle, &state->stack);
+    rvalue_stack_push(state->stack, value, state->stack_handle, &state->stack);
     return value;
 }
 
@@ -1554,11 +1567,13 @@ static VALUE cParser_parse(JSON_ParserConfig *config, VALUE Vsource)
     const char *start;
     RSTRING_GETMEM(Vsource, start, len);
 
+    VALUE stack_handle = 0;
     JSON_ParserState _state = {
         .start = start,
         .cursor = start,
         .end = start + len,
         .stack = &stack,
+        .stack_handle = &stack_handle,
     };
     JSON_ParserState *state = &_state;
 
@@ -1566,8 +1581,8 @@ static VALUE cParser_parse(JSON_ParserConfig *config, VALUE Vsource)
 
     // This may be skipped in case of exception, but
     // it won't cause a leak.
-    rvalue_stack_eagerly_release(state->stack_handle);
-
+    rvalue_stack_eagerly_release(stack_handle);
+    RB_GC_GUARD(stack_handle);
     json_ensure_eof(state);
 
     return result;
@@ -1605,26 +1620,19 @@ static void JSON_ParserConfig_mark(void *ptr)
     rb_gc_mark(config->decimal_class);
 }
 
-static void JSON_ParserConfig_free(void *ptr)
-{
-    JSON_ParserConfig *config = ptr;
-    ruby_xfree(config);
-}
-
 static size_t JSON_ParserConfig_memsize(const void *ptr)
 {
     return sizeof(JSON_ParserConfig);
 }
 
 static const rb_data_type_t JSON_ParserConfig_type = {
-    "JSON::Ext::Parser/ParserConfig",
-    {
+    .wrap_struct_name = "JSON::Ext::Parser/ParserConfig",
+    .function = {
         JSON_ParserConfig_mark,
-        JSON_ParserConfig_free,
+        RUBY_DEFAULT_FREE,
         JSON_ParserConfig_memsize,
     },
-    0, 0,
-    RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_WB_PROTECTED | RUBY_TYPED_FROZEN_SHAREABLE,
+    .flags = RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_WB_PROTECTED | RUBY_TYPED_FROZEN_SHAREABLE | RUBY_TYPED_EMBEDDABLE,
 };
 
 static VALUE cJSON_parser_s_allocate(VALUE klass)
diff --git a/lib/bundled_gems.rb b/lib/bundled_gems.rb
index b64991af0ca050..a287c49a34d22a 100644
--- a/lib/bundled_gems.rb
+++ b/lib/bundled_gems.rb
@@ -137,8 +137,8 @@ def self.warning?(name, specs: nil)
       # Don't warn if the feature is found outside the standard library
       # (e.g., benchmark-ips's lib dir is on $LOAD_PATH but not in specs)
       resolved = $LOAD_PATH.resolve_feature_path(feature) rescue nil
-      if resolved
-        return unless resolved[1].start_with?(LIBDIR) || resolved[1].start_with?(ARCHDIR)
+      if resolved && !resolved[1].start_with?(LIBDIR, ARCHDIR)
+        return
       end
     end
 
diff --git a/marshal.c b/marshal.c
index e2a0ce6dd10210..199923df4df7f9 100644
--- a/marshal.c
+++ b/marshal.c
@@ -1879,6 +1879,9 @@ r_object_for(struct load_arg *arg, bool partial, int *ivp, VALUE extmod, int typ
         }
         v = (VALUE)link;
         if (!st_lookup(arg->partial_objects, (st_data_t)v, &link)) {
+            if (arg->freeze && RB_TYPE_P(v, T_STRING)) {
+                v = rb_str_to_interned_str(v);
+            }
             v = r_post_proc(v, arg);
         }
         break;
diff --git a/test/ruby/test_marshal.rb b/test/ruby/test_marshal.rb
index eb669948017d98..05d3ceb60a5387 100644
--- a/test/ruby/test_marshal.rb
+++ b/test/ruby/test_marshal.rb
@@ -1002,5 +1002,19 @@ def test_modules_and_classes_are_not_frozen
       refute_predicate Object, :frozen?
       refute_predicate Kernel, :frozen?
     end
+
+    def test_linked_strings_are_frozen
+      str = "test"
+      str.instance_variable_set(:@self, str)
+      source = [str, str]
+
+      objects = Marshal.load(encode(source), freeze: true)
+      assert_predicate objects[0], :frozen?
+      assert_predicate objects[1], :frozen?
+      assert_same objects[0], objects[1]
+      assert_same objects[0], objects[0].instance_variable_get(:@self)
+      assert_same objects[1], objects[1].instance_variable_get(:@self)
+      assert_same objects[0].instance_variable_get(:@self), objects[1].instance_variable_get(:@self)
+    end
   end
 end