memory_block_id
return sysfs_emit(buf, "%08lx\n", memory_block_id(mem->start_section_nr));
unsigned long block_id = memory_block_id(section_nr);
if (block_id != ULONG_MAX && memory_block_id(nr) == block_id)
block_id = memory_block_id(nr);
return memory_block_id(pfn_to_section_nr(pfn));