MAP_ANON          219 os/unix/ngx_freebsd_rfork_thread.c     zone = mmap(red_zone, rz_size, PROT_NONE, MAP_ANON, -1, 0);
MAP_ANON           18 os/unix/ngx_shmem.c                                 MAP_ANON|MAP_SHARED, -1, 0);