[PATCH 08/12] mm, ksm: convert write_protect_page() to page_check_walk()

[Kirill A. Shutemov]

For consistency, it worth converting all page_check_address() to
page_check_walk(), so we could drop the former.

Signed-off-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com>
---
 mm/ksm.c | 34 ++++++++++++++++++----------------
 1 file changed, 18 insertions(+), 16 deletions(-)

diff --git a/mm/ksm.c b/mm/ksm.c
index 9ae6011a41f8..6653ca186cfe 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -850,33 +850,35 @@ static int write_protect_page(struct vm_area_struct *vma, 
struct page *page,
                              pte_t *orig_pte)
 {
        struct mm_struct *mm = vma->vm_mm;
-       unsigned long addr;
-       pte_t *ptep;
-       spinlock_t *ptl;
+       struct page_check_walk pcw = {
+               .page = page,
+               .vma = vma,
+       };
        int swapped;
        int err = -EFAULT;
        unsigned long mmun_start;       /* For mmu_notifiers */
        unsigned long mmun_end;         /* For mmu_notifiers */
 
-       addr = page_address_in_vma(page, vma);
-       if (addr == -EFAULT)
+       pcw.address = page_address_in_vma(page, vma);
+       if (pcw.address == -EFAULT)
                goto out;
 
        BUG_ON(PageTransCompound(page));
 
-       mmun_start = addr;
-       mmun_end   = addr + PAGE_SIZE;
+       mmun_start = pcw.address;
+       mmun_end   = pcw.address + PAGE_SIZE;
        mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
 
-       ptep = page_check_address(page, mm, addr, &ptl, 0);
-       if (!ptep)
+       if (!page_check_walk(&pcw))
                goto out_mn;
+       if (WARN_ONCE(!pcw.pte, "Unexpected PMD mapping?"))
+               goto out_unlock;
 
-       if (pte_write(*ptep) || pte_dirty(*ptep)) {
+       if (pte_write(*pcw.pte) || pte_dirty(*pcw.pte)) {
                pte_t entry;
 
                swapped = PageSwapCache(page);
-               flush_cache_page(vma, addr, page_to_pfn(page));
+               flush_cache_page(vma, pcw.address, page_to_pfn(page));
                /*
                 * Ok this is tricky, when get_user_pages_fast() run it doesn't
                 * take any lock, therefore the check that we are going to make
@@ -886,25 +888,25 @@ static int write_protect_page(struct vm_area_struct *vma, 
struct page *page,
                 * this assure us that no O_DIRECT can happen after the check
                 * or in the middle of the check.
                 */
-               entry = ptep_clear_flush_notify(vma, addr, ptep);
+               entry = ptep_clear_flush_notify(vma, pcw.address, pcw.pte);
                /*
                 * Check that no O_DIRECT or similar I/O is in progress on the
                 * page
                 */
                if (page_mapcount(page) + 1 + swapped != page_count(page)) {
-                       set_pte_at(mm, addr, ptep, entry);
+                       set_pte_at(mm, pcw.address, pcw.pte, entry);
                        goto out_unlock;
                }
                if (pte_dirty(entry))
                        set_page_dirty(page);
                entry = pte_mkclean(pte_wrprotect(entry));
-               set_pte_at_notify(mm, addr, ptep, entry);
+               set_pte_at_notify(mm, pcw.address, pcw.pte, entry);
        }
-       *orig_pte = *ptep;
+       *orig_pte = *pcw.pte;
        err = 0;
 
 out_unlock:
-       pte_unmap_unlock(ptep, ptl);
+       page_check_walk_done(&pcw);
 out_mn:
        mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
 out:
-- 
2.11.0