Ok this has 'come back' because upstream have rather unhelpfully renamed the option from SECURITY_DEFAULT_MMAP_MIN_ADDR to DEFAULT_MMAP_MIN_ADDR and so the option ended up defaulting to the upstream default of 4096 across the board. Will reinstate the preferred values.
Ok this has 'come back' because upstream have rather unhelpfully renamed the option from SECURITY_ DEFAULT_ MMAP_MIN_ ADDR to DEFAULT_ MMAP_MIN_ ADDR and so the option ended up defaulting to the upstream default of 4096 across the board. Will reinstate the preferred values.