out: return NULL; 
no_page_table: /* * When core dumping an enormous anonymous area that nobody * has touched so far, we don't want to allocate page tables. */ if (flags & FOLL_ANON) { page = ZERO_PAGE(address); if (flags & FOLL_GET) get_page(page); BUG_ON(flags & FOLL_WRITE); } return page; 
struct page *follow_page(struct mm_struct *mm, unsigned long address, int write){	pgd_t *pgd;	pud_t *pud;	pmd_t *pmd;	pte_t *ptep, pte;	unsigned long pfn;	struct page *page;	page = follow_huge_addr(mm, address, write);	if (! IS_ERR(page))		return page;	pgd = pgd_offset(mm, address);	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))		goto out;	pud = pud_offset(pgd, address);	if (pud_none(*pud) || unlikely(pud_bad(*pud)))		goto out;		pmd = pmd_offset(pud, address);	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))		goto out;	if (pmd_huge(*pmd))		return follow_huge_pmd(mm, address, pmd, write);	ptep = pte_offset_map(pmd, address);	if (!ptep)		goto out;	pte = *ptep;	pte_unmap(ptep);	if (pte_present(pte)) {		if (write && !pte_write(pte))			goto out;		pfn = pte_pfn(pte);		if (pfn_valid(pfn)) {			page = pfn_to_page(pfn);			if (write && !pte_dirty(pte) &&!PageDirty(page))				set_page_dirty(page);			mark_page_accessed(page);			return page;		}	}out:	return NULL;}
4520	/local/tlutelli/issta_data/temp/c/2005_temp/2005/4520/deceb6cd17e6dfafe4c4f81b1b4153bc41b2cb70/memory.c/clean/mm/memory.c