anon_vma_clone
int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src,
rc = anon_vma_clone(vma, pvma, VMA_OP_FORK);
if (anon_vma_clone(new_vma, vma, VMA_OP_REMAP))
err = anon_vma_clone(new, vma, VMA_OP_SPLIT);
ret = anon_vma_clone(dst, src, VMA_OP_MERGE_UNFAULTED);