mm, ksm: convert write_protect_page() to use page_vma_mapped_walk()

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

Link: http://lkml.kernel.org/r/20170129173858.45174-9-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/ksm.c b/mm/ksm.c
index 28bc5ab..8960f6e 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -856,33 +856,35 @@ 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_vma_mapped_walk pvmw = {
+               .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)
+       pvmw.address = page_address_in_vma(page, vma);
+       if (pvmw.address == -EFAULT)
                goto out;
 
        BUG_ON(PageTransCompound(page));
 
-       mmun_start = addr;
-       mmun_end   = addr + PAGE_SIZE;
+       mmun_start = pvmw.address;
+       mmun_end   = pvmw.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_vma_mapped_walk(&pvmw))
                goto out_mn;
+       if (WARN_ONCE(!pvmw.pte, "Unexpected PMD mapping?"))
+               goto out_unlock;
 
-       if (pte_write(*ptep) || pte_dirty(*ptep)) {
+       if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte)) {
                pte_t entry;
 
                swapped = PageSwapCache(page);
-               flush_cache_page(vma, addr, page_to_pfn(page));
+               flush_cache_page(vma, pvmw.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
@@ -892,25 +894,25 @@ 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, pvmw.address, pvmw.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, pvmw.address, pvmw.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, pvmw.address, pvmw.pte, entry);
        }
-       *orig_pte = *ptep;
+       *orig_pte = *pvmw.pte;
        err = 0;
 
 out_unlock:
-       pte_unmap_unlock(ptep, ptl);
+       page_vma_mapped_walk_done(&pvmw);
 out_mn:
        mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
 out: