ksm: cleanup: introduce find_mergeable_vma()

There are multiple places which perform the same check.  Add a new
find_mergeable_vma() to handle this.

Signed-off-by: Bob Liu <lliubbo@gmail.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 19 insertions, 15 deletions

diff --git a/mm/ksm.c b/mm/ksm.c
index a6d3fb7e6c10..47c885368890 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -374,6 +374,20 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr)
         return (ret & VM_FAULT_OOM) ? -ENOMEM : 0;
 }
 
+static struct vm_area_struct *find_mergeable_vma(struct mm_struct *mm,
+                unsigned long addr)
+{
+        struct vm_area_struct *vma;
+        if (ksm_test_exit(mm))
+                return NULL;
+        vma = find_vma(mm, addr);
+        if (!vma || vma->vm_start > addr)
+                return NULL;
+        if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma)
+                return NULL;
+        return vma;
+}
+
 static void break_cow(struct rmap_item *rmap_item)
 {
         struct mm_struct *mm = rmap_item->mm;
@@ -387,15 +401,9 @@ static void break_cow(struct rmap_item *rmap_item)
         put_anon_vma(rmap_item->anon_vma);
 
         down_read(&mm->mmap_sem);
-        if (ksm_test_exit(mm))
-                goto out;
-        vma = find_vma(mm, addr);
-        if (!vma || vma->vm_start > addr)
-                goto out;
-        if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma)
-                goto out;
-        break_ksm(vma, addr);
-out:
+        vma = find_mergeable_vma(mm, addr);
+        if (vma)
+                break_ksm(vma, addr);
         up_read(&mm->mmap_sem);
 }
 
@@ -421,12 +429,8 @@ static struct page *get_mergeable_page(struct rmap_item *rmap_item)
         struct page *page;
 
         down_read(&mm->mmap_sem);
-        if (ksm_test_exit(mm))
-                goto out;
-        vma = find_vma(mm, addr);
-        if (!vma || vma->vm_start > addr)
-                goto out;
-        if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma)
+        vma = find_mergeable_vma(mm, addr);
+        if (!vma)
                 goto out;
 
         page = follow_page(vma, addr, FOLL_GET);