struct pglist_data(pg_data_t)

　　1 struct pglist_data pg_data_t

typedef struct pglist_data {
        struct zone node_zones[MAX_NR_ZONES];
        struct zonelist node_zonelists[MAX_ZONELISTS];
        int nr_zones;
#ifdef CONFIG_FLAT_NODE_MEM_MAP /* means !SPARSEMEM */
        struct page *node_mem_map;
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
        struct page_cgroup *node_page_cgroup;
#endif
#endif
#ifndef CONFIG_NO_BOOTMEM
        struct bootmem_data *bdata;
#endif
#ifdef CONFIG_MEMORY_HOTPLUG
        /*
         * Must be held any time you expect node_start_pfn, node_present_pages
         * or node_spanned_pages stay constant.  Holding this will also
         * guarantee that any pfn_valid() stays that way.
         *
         * Nests above zone->lock and zone->size_seqlock.
         */
        spinlock_t node_size_lock;
#endif
        unsigned long node_start_pfn;
        unsigned long node_present_pages; /* total number of physical pages */
        unsigned long node_spanned_pages; /* total size of physical page
                                             range, including holes */
        int node_id;
        wait_queue_head_t kswapd_wait;
        struct task_struct *kswapd;
        int kswapd_max_order;
} pg_data_t;

　　2 struct zonenode_zones[MAX_NE_ZONES]

struct zone node_zones[MAX_NR_ZONES];
//每个内存节点最多包含3个内存页区
//DMA最低位，normal中间位置，HighMem最高位置
//MAX_NR_ZONES枚举在include/linux/mmzone.h的struct zone_type中

　　3 struct zonelist node_zonelists[MAX_ZONELISTS]

struct zonelist node_zonelists[MAX_ZONELISTS];
//上一行的struct node_zone[]数组中 0-DMA,1-normal,2-HighMem
//这里的node_zonelists[]数组中 0-normal,1-DMA,2-HighMem
//故其对应关系为node_zonelists[0/1/2]->zone[0] = &node_zones[1/0/2]

　　3 int nr_zones

int nr_zones;        //内存页区数量

　　4 struct page *node_mem_map

　　　struct page_cgroup *node_page_cgroup

#ifdef CONFIG_FLAT_NODE_MEM_MAP /* means !SPARSEMEM */
        struct page *node_mem_map;
#ifdef CONFIG_CGROUP_MEM_RES_CTLR
        struct page_cgroup *node_page_cgroup;
#endif
#endif
//struct page *node_mem_map 表示该节点内存所有页描述结构变量空间的起始地址
//struct bootmem_data *bdata内存节点启动阶段内存管理数据结构指针，具体如下
typedef struct bootmem_data {
        unsigned long node_min_pfn;    //内存node空间的物理基址
        unsigned long node_low_pfn;    //.....物理终址
        void *node_bootmem_map;       //.....虚拟起始地址，mem_init()可将其清除为NULL
        unsigned long last_end_off;    //上次分配结束时的地址偏移量
        unsigned long hint_idx;        //上一次从本内存节点中的物理起始地址的的相对偏移量
        struct list_head list;                     
} bootmem_data_t;