unsigned long do_brk(unsigned long addr, unsigned long len)

{

    struct mm_struct * mm = current->mm;

    struct vm_area_struct * vma, * prev;

    unsigned long flags;

......

    mm->total_vm += len >> PAGE_SHIFT;

    if (flags & VM_LOCKED) {

        mm->locked_vm += len >> PAGE_SHIFT;

        make_pages_present(addr, addr + len);

    }

    return addr;

......

}

#include <stdlib.h>

#include <stdio.h>



//  char s[100 * 1024 * 1024];

void fun()

{

    char s[100 * 1024 * 1024];

    getchar();



    for ( int i = 0; i < 100 * 1024 * 1024; i ++ )

        s[i] = 0;

    getchar();

}

int main()

{

    fun();

//  char *s = (char *)malloc(100 * 1024 * 1024);

//  printf("s = %p
", s);

//  getchar();

//  for ( int i = 0; i < 100 * 1024 * 1024; i += 8 * 1024 )

//      s[i] = 0;

//  getchar();

}