Linux内核中关于内存的数据结构

• 物理页面　　

/*
 * Try to keep the most commonly accessed fields in single cache lines
 * here (16 bytes or greater).  This ordering should be particularly
 * beneficial on 32-bit processors.
 *
 * The first line is data used in page cache lookup, the second line
 * is used for linear searches (eg. clock algorithm scans). 
 */
typedef struct page {
    struct list_head list;
    struct address_space *mapping;
    unsigned long index;
    struct page *next_hash;
    atomic_t count;
    unsigned long flags;       /* atomic flags, some possibly updated asynchronously */
    struct list_head lru;
    unsigned long age;
    wait_queue_head_t wait;
    struct page **pprev_hash;
    struct buffer_head * buffers;
    void *virtual;             /* non-NULL if kmapped */
    struct zone_struct *zone;
} mem_map_t;

• 虚拟空间

/*
 * Linux kernel virtual memory manager primitives.
 * The idea being to have a "virtual" mm in the same way
 * we have a virtual fs - giving a cleaner interface to the
 * mm details, and allowing different kinds of memory mappings
 * (from shared memory to executable loading to arbitrary
 * mmap() functions).
 */

/*
 * This struct defines a memory VMM memory area. There is one of these
 * per VM-area/task.  A VM area is any part of the process virtual memory
 * space that has a special rule for the page-fault handlers (ie a shared
 * library, the executable area etc).
 */
struct vm_area_struct {
    struct mm_struct * vm_mm;    /* VM area parameters */
    unsigned long vm_start;
    unsigned long vm_end;

    /* linked list of VM areas per task, sorted by address */
    struct vm_area_struct *vm_next;

    pgprot_t vm_page_prot;
    unsigned long vm_flags;

    /* AVL tree of VM areas per task, sorted by address */
    short vm_avl_height;
    struct vm_area_struct * vm_avl_left;
    struct vm_area_struct * vm_avl_right;

    /* For areas with an address space and backing store,
     * one of the address_space->i_mmap{,shared} lists,
     * for shm areas, the list of attaches, otherwise unused.
     */
    struct vm_area_struct *vm_next_share;
    struct vm_area_struct **vm_pprev_share;

    struct vm_operations_struct * vm_ops;
    unsigned long vm_pgoff;        /* offset in PAGE_SIZE units, *not* PAGE_CACHE_SIZE */
    struct file * vm_file;
    unsigned long vm_raend;
    void * vm_private_data;        /* was vm_pte (shared mem) */
};

• 进程用户空间的抽象:mm_struct，一个进程只有一个mm_struct结构，当一个mm_struct结构却可以为多个进程所共享，例如当一个进程创建一个子进程时(vfork或clone)，子进程与父进程共享一个mm_struct，

struct mm_struct {
    struct vm_area_struct * mmap;        /* list of VMAs */
    struct vm_area_struct * mmap_avl;    /* tree of VMAs */
    struct vm_area_struct * mmap_cache;    /* last find_vma result */
    pgd_t * pgd;
    atomic_t mm_users;            /* How many users with user space? */
    atomic_t mm_count;            /* How many references to "struct mm_struct" (users count as 1) */
    int map_count;                /* number of VMAs */
    struct semaphore mmap_sem;
    spinlock_t page_table_lock;

    struct list_head mmlist;        /* List of all active mm's */

    unsigned long start_code, end_code, start_data, end_data;
    unsigned long start_brk, brk, start_stack;
    unsigned long arg_start, arg_end, env_start, env_end;
    unsigned long rss, total_vm, locked_vm;
    unsigned long def_flags;
    unsigned long cpu_vm_mask;
    unsigned long swap_cnt;  /* number of pages to swap on next pass */
    unsigned long swap_address;

    /* Architecture-specific MM context */
    mm_context_t context;
};