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, 25 insertions, 23 deletions

diff --git a/mm/rmap.c b/mm/rmap.c
index 2ee1ef0f317b..46823fb0e801 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -562,6 +562,27 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
         return address;
 }
 
+pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
+{
+        pgd_t *pgd;
+        pud_t *pud;
+        pmd_t *pmd = NULL;
+
+        pgd = pgd_offset(mm, address);
+        if (!pgd_present(*pgd))
+                goto out;
+
+        pud = pud_offset(pgd, address);
+        if (!pud_present(*pud))
+                goto out;
+
+        pmd = pmd_offset(pud, address);
+        if (!pmd_present(*pmd))
+                pmd = NULL;
+out:
+        return pmd;
+}
+
 /*
  * Check that @page is mapped at @address into @mm.
  *
@@ -574,8 +595,6 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
 pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
                           unsigned long address, spinlock_t **ptlp, int sync)
 {
-        pgd_t *pgd;
-        pud_t *pud;
         pmd_t *pmd;
         pte_t *pte;
         spinlock_t *ptl;
@@ -586,17 +605,10 @@ pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
                 goto check;
         }
 
-        pgd = pgd_offset(mm, address);
-        if (!pgd_present(*pgd))
-                return NULL;
-
-        pud = pud_offset(pgd, address);
-        if (!pud_present(*pud))
+        pmd = mm_find_pmd(mm, address);
+        if (!pmd)
                 return NULL;
 
-        pmd = pmd_offset(pud, address);
-        if (!pmd_present(*pmd))
-                return NULL;
         if (pmd_trans_huge(*pmd))
                 return NULL;
 
@@ -1345,8 +1357,6 @@ static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
                 struct vm_area_struct *vma, struct page *check_page)
 {
         struct mm_struct *mm = vma->vm_mm;
-        pgd_t *pgd;
-        pud_t *pud;
         pmd_t *pmd;
         pte_t *pte;
         pte_t pteval;
@@ -1366,16 +1376,8 @@ static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
         if (end > vma->vm_end)
                 end = vma->vm_end;
 
-        pgd = pgd_offset(mm, address);
-        if (!pgd_present(*pgd))
-                return ret;
-
-        pud = pud_offset(pgd, address);
-        if (!pud_present(*pud))
-                return ret;
-
-        pmd = pmd_offset(pud, address);
-        if (!pmd_present(*pmd))
+        pmd = mm_find_pmd(mm, address);
+        if (!pmd)
                 return ret;
 
         mmun_start = address;