+#ifdef USE_SYSTEM_MALLOC
+ TRACE("m1", "nbd_free: %p", x, 0);
+#ifndef NDEBUG
+ memset(x, 0xcd, sizeof(void *)); // bear trap
+#endif//NDEBUG
+ free(x);
+ return;
+#endif//USE_SYSTEM_MALLOC
+ TRACE("m1", "nbd_free: block %p region %p", x, (size_t)x & ~MASK(REGION_SCALE));
+