Commit 81b4082d authored by Nikita Danilov's avatar Nikita Danilov Committed by Linus Torvalds
Browse files

[PATCH] mm: rmap.c cleanup 



mm/rmap.c:page_referenced_one() and mm/rmap.c:try_to_unmap_one() contain
identical code that

 - takes mm->page_table_lock;

 - drills through page tables;

 - checks that correct pte is reached.

Coalesce this into page_check_address()

Signed-off-by: default avatarNikita Danilov <nikita@clusterfs.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 119f657c

mm/rmap.c

+50 −63
Original line number Diff line number Diff line
@@ -242,6 +242,42 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) 
	return vma_address(page, vma);

}



/*

 * Check that @page is mapped at @address into @mm.

 *

 * On success returns with mapped pte and locked mm->page_table_lock.

 */

static pte_t *page_check_address(struct page *page, struct mm_struct *mm,

					unsigned long address)

{

	pgd_t *pgd;

	pud_t *pud;

	pmd_t *pmd;

	pte_t *pte;



	/*

	 * We need the page_table_lock to protect us from page faults,

	 * munmap, fork, etc...

	 */

	spin_lock(&mm->page_table_lock);

	pgd = pgd_offset(mm, address);

	if (likely(pgd_present(*pgd))) {

		pud = pud_offset(pgd, address);

		if (likely(pud_present(*pud))) {

			pmd = pmd_offset(pud, address);

			if (likely(pmd_present(*pmd))) {

				pte = pte_offset_map(pmd, address);

				if (likely(pte_present(*pte) &&

					   page_to_pfn(page) == pte_pfn(*pte)))

					return pte;

				pte_unmap(pte);

			}

		}

	}

	spin_unlock(&mm->page_table_lock);

	return ERR_PTR(-ENOENT);

}



/*

 * Subfunctions of page_referenced: page_referenced_one called

 * repeatedly from either page_referenced_anon or page_referenced_file.
@@ -251,9 +287,6 @@ static int page_referenced_one(struct page *page, 
{

	struct mm_struct *mm = vma->vm_mm;

	unsigned long address;

	pgd_t *pgd;

	pud_t *pud;

	pmd_t *pmd;

	pte_t *pte;

	int referenced = 0;
@@ -263,27 +296,8 @@ static int page_referenced_one(struct page *page, 
	if (address == -EFAULT)

		goto out;



	spin_lock(&mm->page_table_lock);



	pgd = pgd_offset(mm, address);

	if (!pgd_present(*pgd))

		goto out_unlock;



	pud = pud_offset(pgd, address);

	if (!pud_present(*pud))

		goto out_unlock;



	pmd = pmd_offset(pud, address);

	if (!pmd_present(*pmd))

		goto out_unlock;



	pte = pte_offset_map(pmd, address);

	if (!pte_present(*pte))

		goto out_unmap;



	if (page_to_pfn(page) != pte_pfn(*pte))

		goto out_unmap;



	pte = page_check_address(page, mm, address);

	if (!IS_ERR(pte)) {

		if (ptep_clear_flush_young(vma, address, pte))

			referenced++;
@@ -291,11 +305,9 @@ static int page_referenced_one(struct page *page, 
			referenced++;



		(*mapcount)--;



out_unmap:

		pte_unmap(pte);

out_unlock:

		spin_unlock(&mm->page_table_lock);

	}

out:

	return referenced;

}
@@ -502,9 +514,6 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma) 
{

	struct mm_struct *mm = vma->vm_mm;

	unsigned long address;

	pgd_t *pgd;

	pud_t *pud;

	pmd_t *pmd;

	pte_t *pte;

	pte_t pteval;

	int ret = SWAP_AGAIN;
@@ -515,30 +524,9 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma) 
	if (address == -EFAULT)

		goto out;



	/*

	 * We need the page_table_lock to protect us from page faults,

	 * munmap, fork, etc...

	 */

	spin_lock(&mm->page_table_lock);



	pgd = pgd_offset(mm, address);

	if (!pgd_present(*pgd))

		goto out_unlock;



	pud = pud_offset(pgd, address);

	if (!pud_present(*pud))

		goto out_unlock;



	pmd = pmd_offset(pud, address);

	if (!pmd_present(*pmd))

		goto out_unlock;



	pte = pte_offset_map(pmd, address);

	if (!pte_present(*pte))

		goto out_unmap;



	if (page_to_pfn(page) != pte_pfn(*pte))

		goto out_unmap;

	pte = page_check_address(page, mm, address);

	if (IS_ERR(pte))

		goto out;



	/*

	 * If the page is mlock()d, we cannot swap it out.
@@ -604,7 +592,6 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma) 


out_unmap:

	pte_unmap(pte);

out_unlock:

	spin_unlock(&mm->page_table_lock);

out:

	return ret;
@@ -708,7 +695,6 @@ static void try_to_unmap_cluster(unsigned long cursor, 
	}



	pte_unmap(pte);



out_unlock:

	spin_unlock(&mm->page_table_lock);

}
@@ -860,3 +846,4 @@ int try_to_unmap(struct page *page) 
		ret = SWAP_SUCCESS;

	return ret;

}