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[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: Nikita Danilov <nikita@clusterfs.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Nikita Danilov 2005-05-01 08:58:36 -07:00 committed by Linus Torvalds
parent 119f657c72
commit 81b4082dc7
1 changed files with 50 additions and 63 deletions
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113
mm/rmap.c
View File

@ -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;
@ -263,39 +296,18 @@ static int page_referenced_one(struct page *page,
if (address == -EFAULT)
goto out;
spin_lock(&mm->page_table_lock);
pte = page_check_address(page, mm, address);
if (!IS_ERR(pte)) {
if (ptep_clear_flush_young(vma, address, pte))
referenced++;
pgd = pgd_offset(mm, address);
if (!pgd_present(*pgd))
goto out_unlock;
if (mm != current->mm && !ignore_token && has_swap_token(mm))
referenced++;
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;
if (ptep_clear_flush_young(vma, address, pte))
referenced++;
if (mm != current->mm && !ignore_token && has_swap_token(mm))
referenced++;
(*mapcount)--;
out_unmap:
pte_unmap(pte);
out_unlock:
spin_unlock(&mm->page_table_lock);
(*mapcount)--;
pte_unmap(pte);
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;
}