* anon_vma->lock
* mm->page_table_lock
* zone->lru_lock (in mark_page_accessed)
- * swap_list_lock (in swap_free etc's swap_info_get)
+ * swap_lock (in swap_duplicate, swap_info_get)
* mmlist_lock (in mmput, drain_mmlist and others)
- * swap_device_lock (in swap_duplicate, swap_info_get)
* mapping->private_lock (in __set_page_dirty_buffers)
* inode_lock (in set_page_dirty's __mark_inode_dirty)
* sb_lock (within inode_lock in fs/fs-writeback.c)
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.
+ */
+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.
{
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;
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;
-
- if (ptep_clear_flush_young(vma, address, pte))
- referenced++;
-
- if (mm != current->mm && !ignore_token && has_swap_token(mm))
- referenced++;
+ pte = page_check_address(page, mm, address);
+ if (!IS_ERR(pte)) {
+ if (ptep_clear_flush_young(vma, address, pte))
+ referenced++;
- (*mapcount)--;
+ if (mm != current->mm && !ignore_token && has_swap_token(mm))
+ referenced++;
-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;
}
{
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;
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.
goto out_unmap;
}
- /*
- * Don't pull an anonymous page out from under get_user_pages.
- * GUP carefully breaks COW and raises page count (while holding
- * page_table_lock, as we have here) to make sure that the page
- * cannot be freed. If we unmap that page here, a user write
- * access to the virtual address will bring back the page, but
- * its raised count will (ironically) be taken to mean it's not
- * an exclusive swap page, do_wp_page will replace it by a copy
- * page, and the user never get to see the data GUP was holding
- * the original page for.
- *
- * This test is also useful for when swapoff (unuse_process) has
- * to drop page lock: its reference to the page stops existing
- * ptes from being unmapped, so swapoff can make progress.
- */
- if (PageSwapCache(page) &&
- page_count(page) != page_mapcount(page) + 2) {
- ret = SWAP_FAIL;
- goto out_unmap;
- }
-
/* Nuke the page table entry. */
flush_cache_page(vma, address, page_to_pfn(page));
pteval = ptep_clear_flush(vma, address, pte);
dec_mm_counter(mm, anon_rss);
}
- inc_mm_counter(mm, rss);
+ dec_mm_counter(mm, rss);
page_remove_rmap(page);
page_cache_release(page);
out_unmap:
pte_unmap(pte);
-out_unlock:
spin_unlock(&mm->page_table_lock);
out:
return ret;
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
- pte_t *pte;
+ pte_t *pte, *original_pte;
pte_t pteval;
struct page *page;
unsigned long address;
if (!pmd_present(*pmd))
goto out_unlock;
- for (pte = pte_offset_map(pmd, address);
+ for (original_pte = pte = pte_offset_map(pmd, address);
address < end; pte++, address += PAGE_SIZE) {
if (!pte_present(*pte))
(*mapcount)--;
}
- pte_unmap(pte);
-
+ pte_unmap(original_pte);
out_unlock:
spin_unlock(&mm->page_table_lock);
}
ret = SWAP_SUCCESS;
return ret;
}
+
projects / linux-2.6 / blobdiff