linux – 为什么mm_struct-> start_stack和vm_area_struct-&am

据我了解 Linux内核中的内存管理,有一个mm_struct结构负责每个进程中的地址空间.一个重要的存储区域是堆栈.这应该由vm_area_struct内存区域标识,mm_struct本身有一个指针mm_struct-> stack_start,它是堆栈的地址.

我遇到了下面的代码,我无法理解的是为什么任何内存区域的起始/结束地址都不等于mm_struct-> stack_start值.任何帮助理解这一点将非常感激.谢谢

加载已编译内核模块的一些结果：

Vma number 14: Starts at 0x7fff4bb68000,Ends at 0x7fff4bb8a000
Vma number 15: Starts at 0x7fff4bbfc000,Ends at 0x7fff4bbfe000
Vma number 16: Starts at 0x7fff4bbfe000,Ends at 0x7fff4bc00000
Code Segment start = 0x400000,end = 0x400854
Data Segment start = 0x600858,end = 0x600a94
Stack Segment start = 0x7fff4bb88420

可以发现堆栈段启动(0x7fff4bb88420)属于vma号14但我不知道地址是不同的.

内核模块源代码：

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/mm.h>

static int pid_mem = 1;

static void print_mem(struct task_struct *task)
{
        struct mm_struct *mm;
        struct vm_area_struct *vma;
        int count = 0;
        mm = task->mm;
        printk("nThis mm_struct has %d vmas.n",mm->map_count);
        for (vma = mm->mmap ; vma ; vma = vma->vm_next) {
                printk ("nVma number %d: n",++count);
                printk("  Starts at 0x%lx,Ends at 0x%lxn",vma->vm_start,vma->vm_end);
        }
        printk("nCode  Segment start = 0x%lx,end = 0x%lx n"
                 "Data  Segment start = 0x%lx,end = 0x%lxn"
                 "Stack Segment start = 0x%lxn",mm->start_code,mm->end_code,mm->start_data,mm->end_data,mm->start_stack);
}

static int mm_exp_load(void){
        struct task_struct *task;
        printk("nGot the process id to look up as %d.n",pid_mem);
        for_each_process(task) {
                if ( task->pid == pid_mem) {
                        printk("%s[%d]n",task->comm,task->pid);
                        print_mem(task);
                }
        }
        return 0;
}

static void mm_exp_unload(void)
{
        printk("nPrint segment information module exiting.n");
}

module_init(mm_exp_load);
module_exit(mm_exp_unload);
module_param(pid_mem,int,0);

MODULE_AUTHOR ("Krishnakumar. R,rkrishnakumar@gmail.com");
MODULE_DESCRIPTION ("Print segment information");
MODULE_LICENSE("GPL");