alloc_vma
struct vm_area_struct *vma = alloc_vma(mm, start, end, pgoff, vm_flags);
struct vm_area_struct *alloc_vma(struct mm_struct *mm,
struct vm_area_struct *vma_left = alloc_vma(&mm, 0, 0x1000, 0, vm_flags);
struct vm_area_struct *vma_right = alloc_vma(&mm, 0x2000, 0x3000, 2, vm_flags);
struct vm_area_struct *init_vma = alloc_vma(&mm, 0, 0x3000, 0, vm_flags);
struct vm_area_struct *vma = alloc_vma(&mm, 0, 0x1000, 0, vm_flags);
struct vm_area_struct *vma = alloc_vma(&mm, 0, 0x3000, 0, vm_flags);