thp: introduce hugepage_get_pmd()

Introduce hugepage_get_pmd() to simple code.

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 20037114297a7a4ff03cc9d9fe0a17a0a1f62d25..454bb1a90f55f46463a0226b3a7964a5d57f7e81 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1264,6 +1264,25 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
        return ret;
 }
 
+static pmd_t *hugepage_get_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);
+out:
+       return pmd;
+}
+
 /*
  * Returns 1 if a given pmd maps a stable (not under splitting) thp.
  * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
@@ -1294,22 +1313,14 @@ pmd_t *page_check_address_pmd(struct page *page,
                              unsigned long address,
                              enum page_check_address_pmd_flag flag)
 {
-       pgd_t *pgd;
-       pud_t *pud;
        pmd_t *pmd, *ret = NULL;
 
        if (address & ~HPAGE_PMD_MASK)
                goto out;
 
-       pgd = pgd_offset(mm, address);
-       if (!pgd_present(*pgd))
-               goto out;
-
-       pud = pud_offset(pgd, address);
-       if (!pud_present(*pud))
+       pmd = hugepage_get_pmd(mm, address);
+       if (!pmd)
                goto out;
-
-       pmd = pmd_offset(pud, address);
        if (pmd_none(*pmd))
                goto out;
        if (pmd_page(*pmd) != page)
@@ -2055,8 +2066,6 @@ static void collapse_huge_page(struct mm_struct *mm,
                                   struct vm_area_struct *vma,
                                   int node)
 {
-       pgd_t *pgd;
-       pud_t *pud;
        pmd_t *pmd, _pmd;
        pte_t *pte;
        pgtable_t pgtable;
@@ -2102,16 +2111,9 @@ static void collapse_huge_page(struct mm_struct *mm,
                goto out;
        VM_BUG_ON(vma->vm_flags & VM_NO_THP);
 
-       pgd = pgd_offset(mm, address);
-       if (!pgd_present(*pgd))
-               goto out;
-
-       pud = pud_offset(pgd, address);
-       if (!pud_present(*pud))
+       pmd = hugepage_get_pmd(mm, address);
+       if (!pmd)
                goto out;
-
-       pmd = pmd_offset(pud, address);
-       /* pmd can't go away or become huge under us */
        if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
                goto out;
 
@@ -2195,8 +2197,6 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
                               unsigned long address,
                               struct page **hpage)
 {
-       pgd_t *pgd;
-       pud_t *pud;
        pmd_t *pmd;
        pte_t *pte, *_pte;
        int ret = 0, referenced = 0, none = 0;
@@ -2207,15 +2207,9 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
 
        VM_BUG_ON(address & ~HPAGE_PMD_MASK);
 
-       pgd = pgd_offset(mm, address);
-       if (!pgd_present(*pgd))
-               goto out;
-
-       pud = pud_offset(pgd, address);
-       if (!pud_present(*pud))
+       pmd = hugepage_get_pmd(mm, address);
+       if (!pmd)
                goto out;
-
-       pmd = pmd_offset(pud, address);
        if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
                goto out;
 
@@ -2508,21 +2502,13 @@ void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd)
 static void split_huge_page_address(struct mm_struct *mm,
                                    unsigned long address)
 {
-       pgd_t *pgd;
-       pud_t *pud;
        pmd_t *pmd;
 
        VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
 
-       pgd = pgd_offset(mm, address);
-       if (!pgd_present(*pgd))
-               return;
-
-       pud = pud_offset(pgd, address);
-       if (!pud_present(*pud))
+       pmd = hugepage_get_pmd(mm, address);
+       if (!pmd)
                return;
-
-       pmd = pmd_offset(pud, address);
        if (!pmd_present(*pmd))
                return;
        /*