PAGE_SIZE - (mapping_base & (PAGE_SIZE-1))
);
memset( (void*)(mapping_base + ofs), 0, PAGE_SIZE - (mapping_base & (PAGE_SIZE-1)));
PAGE_SIZE - (mapping_base & (PAGE_SIZE-1))
);
memset( (void*)(mapping_base + ofs), 0, PAGE_SIZE - (mapping_base & (PAGE_SIZE-1)));