mm,hugetlb: make unmap_ref_private() return void

This function always returns 1, thus no need to check return value in
hugetlb_cow().  By doing so, we can get rid of the unnecessary WARN_ON
call.  While this logic perhaps existed as a way of identifying future
unmap_ref_private() mishandling, reality is it serves no apparent
purpose.

Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 7a0a73d2fcff128850b32af9910a873d6fb384f5..b94752ae791bef5e3c4e53ce83728fa32ad7ed86 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2754,8 +2754,8 @@ void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
  * from other VMAs and let the children be SIGKILLed if they are faulting the
  * same region.
  */
-static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
-                               struct page *page, unsigned long address)
+static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
+                             struct page *page, unsigned long address)
 {
        struct hstate *h = hstate_vma(vma);
        struct vm_area_struct *iter_vma;
@@ -2794,8 +2794,6 @@ static int unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
                                             address + huge_page_size(h), page);
        }
        mutex_unlock(&mapping->i_mmap_mutex);
-
-       return 1;
 }
 
 /*
@@ -2857,20 +2855,18 @@ retry_avoidcopy:
                 */
                if (outside_reserve) {
                        BUG_ON(huge_pte_none(pte));
-                       if (unmap_ref_private(mm, vma, old_page, address)) {
-                               BUG_ON(huge_pte_none(pte));
-                               spin_lock(ptl);
-                               ptep = huge_pte_offset(mm, address & huge_page_mask(h));
-                               if (likely(ptep &&
-                                          pte_same(huge_ptep_get(ptep), pte)))
-                                       goto retry_avoidcopy;
-                               /*
-                                * race occurs while re-acquiring page table
-                                * lock, and our job is done.
-                                */
-                               return 0;
-                       }
-                       WARN_ON_ONCE(1);
+                       unmap_ref_private(mm, vma, old_page, address);
+                       BUG_ON(huge_pte_none(pte));
+                       spin_lock(ptl);
+                       ptep = huge_pte_offset(mm, address & huge_page_mask(h));
+                       if (likely(ptep &&
+                                  pte_same(huge_ptep_get(ptep), pte)))
+                               goto retry_avoidcopy;
+                       /*
+                        * race occurs while re-acquiring page table
+                        * lock, and our job is done.
+                        */
+                       return 0;
                }
 
                /* Caller expects lock to be held */