How to retrieve page pointer from vm_area_struct?

Hi all, I want to retrieve "struct page" pointer from vm_area_struct. How do I write code below example? ------------example code------------ struct task_struct *p; struct vm_area_struct *vma; struct page *page; for_each_process(p) { if (!p->mm) continue; for (vma = p->mm->mmap; vma; vma = vma->vm_next) { for (i = vma->vm_start; i < vma->vm_end; i += PAGE_SIZE) { /* How to get page pointer? */ page = ??? } } }