swapops-0002-Revert-mm-ksm-convert-write_protect_page-to-use-page.patch

   1 From 40e1fa51bc8aa3df1d3a23711b5de62d8251bff5 Mon Sep 17 00:00:00 2001
   2 From: Seth Forshee <seth.forshee@canonical.com>
   3 Date: Wed, 3 May 2017 08:34:52 -0500
   4 Subject: [PATCH 2/4] Revert "mm, ksm: convert write_protect_page() to use
   5  page_vma_mapped_walk()"
   6
   7 This reverts commit 3000e033152a70fa139765b4dbb5baec46b1cc1b.
   8
   9 Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
  10 ---
  11  mm/ksm.c | 34 ++++++++++++++++------------------
  12  1 file changed, 16 insertions(+), 18 deletions(-)
  13
  14 diff --git a/mm/ksm.c b/mm/ksm.c
  15 index 9dd2e58fb6dc..fed4afd8293b 100644
  16 --- a/mm/ksm.c
  17 +++ b/mm/ksm.c
  18 @@ -856,35 +856,33 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
  19                               pte_t *orig_pte)
  20  {
  21         struct mm_struct *mm = vma->vm_mm;
  22 -       struct page_vma_mapped_walk pvmw = {
  23 -               .page = page,
  24 -               .vma = vma,
  25 -       };
  26 +       unsigned long addr;
  27 +       pte_t *ptep;
  28 +       spinlock_t *ptl;
  29         int swapped;
  30         int err = -EFAULT;
  31         unsigned long mmun_start;       /* For mmu_notifiers */
  32         unsigned long mmun_end;         /* For mmu_notifiers */
  33
  34 -       pvmw.address = page_address_in_vma(page, vma);
  35 -       if (pvmw.address == -EFAULT)
  36 +       addr = page_address_in_vma(page, vma);
  37 +       if (addr == -EFAULT)
  38                 goto out;
  39
  40         BUG_ON(PageTransCompound(page));
  41
  42 -       mmun_start = pvmw.address;
  43 -       mmun_end   = pvmw.address + PAGE_SIZE;
  44 +       mmun_start = addr;
  45 +       mmun_end   = addr + PAGE_SIZE;
  46         mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
  47
  48 -       if (!page_vma_mapped_walk(&pvmw))
  49 +       ptep = page_check_address(page, mm, addr, &ptl, 0);
  50 +       if (!ptep)
  51                 goto out_mn;
  52 -       if (WARN_ONCE(!pvmw.pte, "Unexpected PMD mapping?"))
  53 -               goto out_unlock;
  54
  55 -       if (pte_write(*pvmw.pte) || pte_dirty(*pvmw.pte)) {
  56 +       if (pte_write(*ptep) || pte_dirty(*ptep)) {
  57                 pte_t entry;
  58
  59                 swapped = PageSwapCache(page);
  60 -               flush_cache_page(vma, pvmw.address, page_to_pfn(page));
  61 +               flush_cache_page(vma, addr, page_to_pfn(page));
  62                 /*
  63                  * Ok this is tricky, when get_user_pages_fast() run it doesn't
  64                  * take any lock, therefore the check that we are going to make
  65 @@ -894,25 +892,25 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
  66                  * this assure us that no O_DIRECT can happen after the check
  67                  * or in the middle of the check.
  68                  */
  69 -               entry = ptep_clear_flush_notify(vma, pvmw.address, pvmw.pte);
  70 +               entry = ptep_clear_flush_notify(vma, addr, ptep);
  71                 /*
  72                  * Check that no O_DIRECT or similar I/O is in progress on the
  73                  * page
  74                  */
  75                 if (page_mapcount(page) + 1 + swapped != page_count(page)) {
  76 -                       set_pte_at(mm, pvmw.address, pvmw.pte, entry);
  77 +                       set_pte_at(mm, addr, ptep, entry);
  78                         goto out_unlock;
  79                 }
  80                 if (pte_dirty(entry))
  81                         set_page_dirty(page);
  82                 entry = pte_mkclean(pte_wrprotect(entry));
  83 -               set_pte_at_notify(mm, pvmw.address, pvmw.pte, entry);
  84 +               set_pte_at_notify(mm, addr, ptep, entry);
  85         }
  86 -       *orig_pte = *pvmw.pte;
  87 +       *orig_pte = *ptep;
  88         err = 0;
  89
  90  out_unlock:
  91 -       page_vma_mapped_walk_done(&pvmw);
  92 +       pte_unmap_unlock(ptep, ptl);
  93  out_mn:
  94         mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
  95  out:
  96 --
  97 2.7.4
  98