queue-4.9/mm-mempolicy-make-mbind-return-eio-when-mpol_mf_strict-is-specified.patch

   1 From a7f40cfe3b7ada57af9b62fd28430eeb4a7cfcb7 Mon Sep 17 00:00:00 2001
   2 From: Yang Shi <yang.shi@linux.alibaba.com>
   3 Date: Thu, 28 Mar 2019 20:43:55 -0700
   4 Subject: mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified
   5
   6 From: Yang Shi <yang.shi@linux.alibaba.com>
   7
   8 commit a7f40cfe3b7ada57af9b62fd28430eeb4a7cfcb7 upstream.
   9
  10 When MPOL_MF_STRICT was specified and an existing page was already on a
  11 node that does not follow the policy, mbind() should return -EIO.  But
  12 commit 6f4576e3687b ("mempolicy: apply page table walker on
  13 queue_pages_range()") broke the rule.
  14
  15 And commit c8633798497c ("mm: mempolicy: mbind and migrate_pages support
  16 thp migration") didn't return the correct value for THP mbind() too.
  17
  18 If MPOL_MF_STRICT is set, ignore vma_migratable() to make sure it
  19 reaches queue_pages_to_pte_range() or queue_pages_pmd() to check if an
  20 existing page was already on a node that does not follow the policy.
  21 And, non-migratable vma may be used, return -EIO too if MPOL_MF_MOVE or
  22 MPOL_MF_MOVE_ALL was specified.
  23
  24 Tested with https://github.com/metan-ucw/ltp/blob/master/testcases/kernel/syscalls/mbind/mbind02.c
  25
  26 [akpm@linux-foundation.org: tweak code comment]
  27 Link: http://lkml.kernel.org/r/1553020556-38583-1-git-send-email-yang.shi@linux.alibaba.com
  28 Fixes: 6f4576e3687b ("mempolicy: apply page table walker on queue_pages_range()")
  29 Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
  30 Signed-off-by: Oscar Salvador <osalvador@suse.de>
  31 Reported-by: Cyril Hrubis <chrubis@suse.cz>
  32 Suggested-by: Kirill A. Shutemov <kirill@shutemov.name>
  33 Acked-by: Rafael Aquini <aquini@redhat.com>
  34 Reviewed-by: Oscar Salvador <osalvador@suse.de>
  35 Acked-by: David Rientjes <rientjes@google.com>
  36 Cc: Vlastimil Babka <vbabka@suse.cz>
  37 Cc: <stable@vger.kernel.org>
  38 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  39 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  40 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  41
  42 ---
  43  mm/mempolicy.c |   18 ++++++++++++++----
  44  1 file changed, 14 insertions(+), 4 deletions(-)
  45
  46 --- a/mm/mempolicy.c
  47 +++ b/mm/mempolicy.c
  48 @@ -547,11 +547,16 @@ retry:
  49                         goto retry;
  50                 }
  51
  52 -               migrate_page_add(page, qp->pagelist, flags);
  53 +               if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
  54 +                       if (!vma_migratable(vma))
  55 +                               break;
  56 +                       migrate_page_add(page, qp->pagelist, flags);
  57 +               } else
  58 +                       break;
  59         }
  60         pte_unmap_unlock(pte - 1, ptl);
  61         cond_resched();
  62 -       return 0;
  63 +       return addr != end ? -EIO : 0;
  64  }
  65
  66  static int queue_pages_hugetlb(pte_t *pte, unsigned long hmask,
  67 @@ -623,7 +628,12 @@ static int queue_pages_test_walk(unsigne
  68         unsigned long endvma = vma->vm_end;
  69         unsigned long flags = qp->flags;
  70
  71 -       if (!vma_migratable(vma))
  72 +       /*
  73 +        * Need check MPOL_MF_STRICT to return -EIO if possible
  74 +        * regardless of vma_migratable
  75 +        */
  76 +       if (!vma_migratable(vma) &&
  77 +           !(flags & MPOL_MF_STRICT))
  78                 return 1;
  79
  80         if (endvma > end)
  81 @@ -650,7 +660,7 @@ static int queue_pages_test_walk(unsigne
  82         }
  83
  84         /* queue pages from current vma */
  85 -       if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
  86 +       if (flags & MPOL_MF_VALID)
  87                 return 0;
  88         return 1;
  89  }