mm: introduce mm_find_pmd()

Several place need to find the pmd by(mm_struct, address), so introduce a
function to simplify it.

[akpm@linux-foundation.org: fix warning]
Signed-off-by: Bob Liu <lliubbo@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Ni zhan Chen <nizhan.chen@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 12 deletions

diff --git a/mm/ksm.c b/mm/ksm.c
index ae539f0b8aa1..31ae5ea1eac0 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -778,8 +778,6 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
                         struct page *kpage, pte_t orig_pte)
 {
         struct mm_struct *mm = vma->vm_mm;
-        pgd_t *pgd;
-        pud_t *pud;
         pmd_t *pmd;
         pte_t *ptep;
         spinlock_t *ptl;
@@ -792,18 +790,10 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
         if (addr == -EFAULT)
                 goto out;
 
-        pgd = pgd_offset(mm, addr);
-        if (!pgd_present(*pgd))
+        pmd = mm_find_pmd(mm, addr);
+        if (!pmd)
                 goto out;
-
-        pud = pud_offset(pgd, addr);
-        if (!pud_present(*pud))
-                goto out;
-
-        pmd = pmd_offset(pud, addr);
         BUG_ON(pmd_trans_huge(*pmd));
-        if (!pmd_present(*pmd))
-                goto out;
 
         mmun_start = addr;
         mmun_end   = addr + PAGE_SIZE;