diff --git a/src/array.c b/src/array.c
index c6cefbebceb20..86b1056ef4d07 100644
--- a/src/array.c
+++ b/src/array.c
@@ -59,15 +59,6 @@ JL_DLLEXPORT char *jl_array_typetagdata(jl_array_t *a) JL_NOTSAFEPOINT
     return ((char*)jl_array_data(a)) + ((jl_array_ndims(a) == 1 ? (a->maxsize - a->offset) : jl_array_len(a)) * a->elsize) + a->offset;
 }
 
-STATIC_INLINE jl_value_t *jl_array_owner(jl_array_t *a JL_PROPAGATES_ROOT) JL_NOTSAFEPOINT
-{
-    if (a->flags.how == 3) {
-        a = (jl_array_t*)jl_array_data_owner(a);
-        assert(jl_is_string(a) || a->flags.how != 3);
-    }
-    return (jl_value_t*)a;
-}
-
 #if defined(_P64) && defined(UINT128MAX)
 typedef __uint128_t wideint_t;
 #else
@@ -1198,69 +1189,11 @@ JL_DLLEXPORT jl_array_t *jl_array_copy(jl_array_t *ary)
     return new_ary;
 }
 
-// Copy element by element until we hit a young object, at which point
-// we can finish by using `memmove`.
-static NOINLINE ssize_t jl_array_ptr_copy_forward(jl_value_t *owner,
-                                                  void **src_p, void **dest_p,
-                                                  ssize_t n) JL_NOTSAFEPOINT
-{
-    _Atomic(void*) *src_pa = (_Atomic(void*)*)src_p;
-    _Atomic(void*) *dest_pa = (_Atomic(void*)*)dest_p;
-    for (ssize_t i = 0; i < n; i++) {
-        void *val = jl_atomic_load_relaxed(src_pa + i);
-        jl_atomic_store_release(dest_pa + i, val);
-        // `val` is young or old-unmarked
-        if (val && !(jl_astaggedvalue(val)->bits.gc & GC_MARKED)) {
-            jl_gc_queue_root(owner);
-            return i;
-        }
-    }
-    return n;
-}
-
-static NOINLINE ssize_t jl_array_ptr_copy_backward(jl_value_t *owner,
-                                                   void **src_p, void **dest_p,
-                                                   ssize_t n) JL_NOTSAFEPOINT
-{
-    _Atomic(void*) *src_pa = (_Atomic(void*)*)src_p;
-    _Atomic(void*) *dest_pa = (_Atomic(void*)*)dest_p;
-    for (ssize_t i = 0; i < n; i++) {
-        void *val = jl_atomic_load_relaxed(src_pa + n - i - 1);
-        jl_atomic_store_release(dest_pa + n - i - 1, val);
-        // `val` is young or old-unmarked
-        if (val && !(jl_astaggedvalue(val)->bits.gc & GC_MARKED)) {
-            jl_gc_queue_root(owner);
-            return i;
-        }
-    }
-    return n;
-}
-
 // Unsafe, assume inbounds and that dest and src have the same eltype
 JL_DLLEXPORT void jl_array_ptr_copy(jl_array_t *dest, void **dest_p,
                                     jl_array_t *src, void **src_p, ssize_t n) JL_NOTSAFEPOINT
 {
-    assert(dest->flags.ptrarray && src->flags.ptrarray);
-    jl_value_t *owner = jl_array_owner(dest);
-    // Destination is old and doesn't refer to any young object
-    if (__unlikely(jl_astaggedvalue(owner)->bits.gc == GC_OLD_MARKED)) {
-        jl_value_t *src_owner = jl_array_owner(src);
-        // Source is young or being promoted or might refer to young objects
-        // (i.e. source is not an old object that doesn't have wb triggered)
-        if (jl_astaggedvalue(src_owner)->bits.gc != GC_OLD_MARKED) {
-            ssize_t done;
-            if (dest_p < src_p || dest_p > src_p + n) {
-                done = jl_array_ptr_copy_forward(owner, src_p, dest_p, n);
-                dest_p += done;
-                src_p += done;
-            }
-            else {
-                done = jl_array_ptr_copy_backward(owner, src_p, dest_p, n);
-            }
-            n -= done;
-        }
-    }
-    memmove_refs(dest_p, src_p, n);
+    jl_gc_array_ptr_copy(dest, dest_p, src, src_p, n);
 }
 
 JL_DLLEXPORT void jl_array_ptr_1d_push(jl_array_t *a, jl_value_t *item)
diff --git a/src/gc.c b/src/gc.c
index 69ec08b6cf9d4..0f6c13777e265 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -114,6 +114,71 @@ JL_DLLEXPORT void jl_gc_set_cb_notify_external_free(jl_gc_cb_notify_external_fre
         jl_gc_deregister_callback(&gc_cblist_notify_external_free, (jl_gc_cb_func_t)cb);
 }
 
+// Copy element by element until we hit a young object, at which point
+// we can finish by using `memmove`.
+static NOINLINE ssize_t jl_array_ptr_copy_forward(jl_value_t *owner,
+                                                  void **src_p, void **dest_p,
+                                                  ssize_t n) JL_NOTSAFEPOINT
+{
+    _Atomic(void*) *src_pa = (_Atomic(void*)*)src_p;
+    _Atomic(void*) *dest_pa = (_Atomic(void*)*)dest_p;
+    for (ssize_t i = 0; i < n; i++) {
+        void *val = jl_atomic_load_relaxed(src_pa + i);
+        jl_atomic_store_release(dest_pa + i, val);
+        // `val` is young or old-unmarked
+        if (val && !(jl_astaggedvalue(val)->bits.gc & GC_MARKED)) {
+            jl_gc_queue_root(owner);
+            return i;
+        }
+    }
+    return n;
+}
+
+static NOINLINE ssize_t jl_array_ptr_copy_backward(jl_value_t *owner,
+                                                   void **src_p, void **dest_p,
+                                                   ssize_t n) JL_NOTSAFEPOINT
+{
+    _Atomic(void*) *src_pa = (_Atomic(void*)*)src_p;
+    _Atomic(void*) *dest_pa = (_Atomic(void*)*)dest_p;
+    for (ssize_t i = 0; i < n; i++) {
+        void *val = jl_atomic_load_relaxed(src_pa + n - i - 1);
+        jl_atomic_store_release(dest_pa + n - i - 1, val);
+        // `val` is young or old-unmarked
+        if (val && !(jl_astaggedvalue(val)->bits.gc & GC_MARKED)) {
+            jl_gc_queue_root(owner);
+            return i;
+        }
+    }
+    return n;
+}
+
+// Unsafe, assume inbounds and that dest and src have the same eltype
+JL_DLLEXPORT void jl_gc_array_ptr_copy(jl_array_t *dest, void **dest_p,
+                                       jl_array_t *src, void **src_p, ssize_t n) JL_NOTSAFEPOINT
+{
+    assert(dest->flags.ptrarray && src->flags.ptrarray);
+    jl_value_t *owner = jl_array_owner(dest);
+    // Destination is old and doesn't refer to any young object
+    if (__unlikely(jl_astaggedvalue(owner)->bits.gc == GC_OLD_MARKED)) {
+        jl_value_t *src_owner = jl_array_owner(src);
+        // Source is young or being promoted or might refer to young objects
+        // (i.e. source is not an old object that doesn't have wb triggered)
+        if (jl_astaggedvalue(src_owner)->bits.gc != GC_OLD_MARKED) {
+            ssize_t done;
+            if (dest_p < src_p || dest_p > src_p + n) {
+                done = jl_array_ptr_copy_forward(owner, src_p, dest_p, n);
+                dest_p += done;
+                src_p += done;
+            }
+            else {
+                done = jl_array_ptr_copy_backward(owner, src_p, dest_p, n);
+            }
+            n -= done;
+        }
+    }
+    memmove_refs(dest_p, src_p, n);
+}
+
 // Perm gen allocator
 // 2M pool
 #define GC_PERM_POOL_SIZE (2 * 1024 * 1024)
diff --git a/src/julia.h b/src/julia.h
index 710fd11cf9372..2396b7a38a00d 100644
--- a/src/julia.h
+++ b/src/julia.h
@@ -1345,6 +1345,14 @@ STATIC_INLINE int jl_is_array(void *v) JL_NOTSAFEPOINT
     return jl_is_array_type(t);
 }
 
+STATIC_INLINE jl_value_t *jl_array_owner(jl_array_t *a JL_PROPAGATES_ROOT) JL_NOTSAFEPOINT
+{
+    if (a->flags.how == 3) {
+        a = (jl_array_t*)jl_array_data_owner(a);
+        assert(jl_is_string(a) || a->flags.how != 3);
+    }
+    return (jl_value_t*)a;
+}
 
 STATIC_INLINE int jl_is_opaque_closure_type(void *t) JL_NOTSAFEPOINT
 {
diff --git a/src/julia_internal.h b/src/julia_internal.h
index 65e1966385039..6d456b470a116 100644
--- a/src/julia_internal.h
+++ b/src/julia_internal.h
@@ -630,6 +630,8 @@ STATIC_INLINE void jl_gc_wb_buf(void *parent, void *bufptr, size_t minsz) JL_NOT
 }
 #endif // MMTK_GC
 
+JL_DLLEXPORT void jl_gc_array_ptr_copy(jl_array_t *dest, void **dest_p, jl_array_t *src, void **src_p, ssize_t n) JL_NOTSAFEPOINT;
+
 void jl_gc_debug_print_status(void) JL_NOTSAFEPOINT;
 JL_DLLEXPORT void jl_gc_debug_critical_error(void) JL_NOTSAFEPOINT;
 void jl_print_gc_stats(JL_STREAM *s);
diff --git a/src/mmtk-gc.c b/src/mmtk-gc.c
index 06a0a028303ab..9dc21c2ad48db 100644
--- a/src/mmtk-gc.c
+++ b/src/mmtk-gc.c
@@ -480,6 +480,12 @@ void objprofile_reset(void)
 {
 }
 
+JL_DLLEXPORT void jl_gc_array_ptr_copy(jl_array_t *dest, void **dest_p, jl_array_t *src, void **src_p, ssize_t n) JL_NOTSAFEPOINT
+{
+    jl_ptls_t ptls = jl_current_task->ptls;
+    mmtk_memory_region_copy(ptls->mmtk_mutator_ptr, jl_array_owner(src), src_p, jl_array_owner(dest), dest_p, n);
+}
+
 // No inline write barrier -- only used for debugging
 JL_DLLEXPORT void jl_gc_wb1_noinline(const void *parent) JL_NOTSAFEPOINT
 {