mm/gup: check for protnone only if it is a PTE entry

BugLink: http://bugs.launchpad.net/bugs/1671613
Do the prot_none/FOLL_NUMA check after we are sure this is a THP pte.
Archs can implement prot_none such that it can return true for regular
pmd entries.

Link: http://lkml.kernel.org/r/1487498326-8734-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit db08f2030a173fdb95b2e8e28d82c4e8c04df2ac)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

diff --git a/mm/gup.c b/mm/gup.c
index 55315555489d02c411534a958f1a31f79c9fafb5..bb5f3d69f87e0b963a2e4bb243c4f15ca16d0e8d 100644 (file)
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -265,8 +265,6 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
                        return page;
                return no_page_table(vma, flags);
        }
-       if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
-               return no_page_table(vma, flags);
        if (pmd_devmap(*pmd)) {
                ptl = pmd_lock(mm, pmd);
                page = follow_devmap_pmd(vma, address, pmd, flags);
@@ -277,6 +275,9 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
        if (likely(!pmd_trans_huge(*pmd)))
                return follow_page_pte(vma, address, pmd, flags);
 
+       if ((flags & FOLL_NUMA) && pmd_protnone(*pmd))
+               return no_page_table(vma, flags);
+
        ptl = pmd_lock(mm, pmd);
        if (unlikely(!pmd_trans_huge(*pmd))) {
                spin_unlock(ptl);