【file：/mm/page_alloc.c】
/**
 * free_area_init_nodes - Initialise all pg_data_t and zone data
 * @max_zone_pfn: an array of max PFNs for each zone
 *
 * This will call free_area_init_node() for each active node in the system.
 * Using the page ranges provided by add_active_range(), the size of each
 * zone in each node and their holes is calculated. If the maximum PFN
 * between two adjacent zones match, it is assumed that the zone is empty.
 * For example, if arch_max_dma_pfn == arch_max_dma32_pfn, it is assumed
 * that arch_max_dma32_pfn has no pages. It is also assumed that a zone
 * starts where the previous one ended. For example, ZONE_DMA32 starts
 * at arch_max_dma_pfn.
 */
void __init free_area_init_nodes(unsigned long *max_zone_pfn)
{
    unsigned long start_pfn, end_pfn;
    int i, nid;
 
    /* Record where the zone boundaries are */
    memset(arch_zone_lowest_possible_pfn, 0,
                sizeof(arch_zone_lowest_possible_pfn));
    memset(arch_zone_highest_possible_pfn, 0,
                sizeof(arch_zone_highest_possible_pfn));
    arch_zone_lowest_possible_pfn[0] = find_min_pfn_with_active_regions();
    arch_zone_highest_possible_pfn[0] = max_zone_pfn[0];
    for (i = 1; i < MAX_NR_ZONES; i++) {
        if (i == ZONE_MOVABLE)
            continue;
        arch_zone_lowest_possible_pfn[i] =
            arch_zone_highest_possible_pfn[i-1];
        arch_zone_highest_possible_pfn[i] =
            max(max_zone_pfn[i], arch_zone_lowest_possible_pfn[i]);
    }
    arch_zone_lowest_possible_pfn[ZONE_MOVABLE] = 0;
    arch_zone_highest_possible_pfn[ZONE_MOVABLE] = 0;
 
    /* Find the PFNs that ZONE_MOVABLE begins at in each node */
    memset(zone_movable_pfn, 0, sizeof(zone_movable_pfn));
    find_zone_movable_pfns_for_nodes();
 
    /* Print out the zone ranges */
    printk("Zone ranges:\n");
    for (i = 0; i < MAX_NR_ZONES; i++) {
        if (i == ZONE_MOVABLE)
            continue;
        printk(KERN_CONT " %-8s ", zone_names[i]);
        if (arch_zone_lowest_possible_pfn[i] ==
                arch_zone_highest_possible_pfn[i])
            printk(KERN_CONT "empty\n");
        else
            printk(KERN_CONT "[mem %0#10lx-%0#10lx]\n",
                arch_zone_lowest_possible_pfn[i] << PAGE_SHIFT,
                (arch_zone_highest_possible_pfn[i]
                    << PAGE_SHIFT) - 1);
    }
 
    /* Print out the PFNs ZONE_MOVABLE begins at in each node */
    printk("Movable zone start for each node\n");
    for (i = 0; i < MAX_NUMNODES; i++) {
        if (zone_movable_pfn[i])
            printk(" Node %d: %#010lx\n", i,
                   zone_movable_pfn[i] << PAGE_SHIFT);
    }
 
    /* Print out the early node map */
    printk("Early memory node ranges\n");
    for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid)
        printk(" node %3d: [mem %#010lx-%#010lx]\n", nid,
               start_pfn << PAGE_SHIFT, (end_pfn << PAGE_SHIFT) - 1);
 
    /* Initialise every node */
    mminit_verify_pageflags_layout();
    setup_nr_node_ids();
    for_each_online_node(nid) {
        pg_data_t *pgdat = NODE_DATA(nid);
        free_area_init_node(nid, NULL,
                find_min_pfn_for_node(nid), NULL);
 
        /* Any memory on that node */
        if (pgdat->node_present_pages)
            node_set_state(nid, N_MEMORY);
        check_for_memor