struct mm_struct {
    struct vm_area_struct * mmap;        /* list of VMAs */
    struct rb_root mm_rb;
    struct vm_area_struct * mmap_cache;    /* last find_vma result */
    unsigned long (*get_unmapped_area) (struct file *filp,
                unsigned long addr, unsigned long len,
                unsigned long pgoff, unsigned long flags);
    void (*unmap_area) (struct mm_struct *mm, unsigned long addr);
    unsigned long mmap_base;        /* base of mmap area */
    unsigned long task_size;        /* size of task vm space */
    unsigned long cached_hole_size;     /* if non-zero, the largest hole below free_area_cache */
    unsigned long free_area_cache;        /* first hole of size cached_hole_size or larger */
    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 rw_semaphore mmap_sem;
    spinlock_t page_table_lock;        /* Protects page tables and some counters */

    struct list_head mmlist;        /* List of maybe swapped mm‘s.    These are globally strung
                         * together off init_mm.mmlist, and are protected
                         * by mmlist_lock
                         */

    /* Special counters, in some configurations protected by the
     * page_table_lock, in other configurations by being atomic.
     */
    mm_counter_t _file_rss;
    mm_counter_t _anon_rss;

    unsigned long hiwater_rss;    /* High-watermark of RSS usage */
    unsigned long hiwater_vm;    /* High-water virtual memory usage */

    unsigned long total_vm, locked_vm, shared_vm, exec_vm;
    unsigned long stack_vm, reserved_vm, def_flags, nr_ptes;
    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 saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */

    struct linux_binfmt *binfmt;

    cpumask_t cpu_vm_mask;

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

    /* Swap token stuff */
    /*
     * Last value of global fault stamp as seen by this process.
     * In other words, this value gives an indication of how long
     * it has been since this task got the token.
     * Look at mm/thrash.c
     */
    unsigned int faultstamp;
    unsigned int token_priority;
    unsigned int last_interval;

    unsigned long flags; /* Must use atomic bitops to access the bits */

    struct core_state *core_state; /* coredumping support */
#ifdef CONFIG_AIO
    spinlock_t        ioctx_lock;
    struct hlist_head    ioctx_list;
#endif
#ifdef CONFIG_MM_OWNER
    /*
     * "owner" points to a task that is regarded as the canonical
     * user/owner of this mm. All of the following must be true in
     * order for it to be changed:
     *
     * current == mm->owner
     * current->mm != mm
     * new_owner->mm == mm
     * new_owner->alloc_lock is held
     */
    struct task_struct *owner;
#endif

#ifdef CONFIG_PROC_FS
    /* store ref to file /proc/<pid>/exe symlink points to */
    struct file *exe_file;
    unsigned long num_exe_file_vmas;
#endif
#ifdef CONFIG_MMU_NOTIFIER
    struct mmu_notifier_mm *mmu_notifier_mm;
#endif
};