userfaultfd: remove unnecessary WARN_ON() in __mcopy_atomic_hugetlb()

These warning here is to make sure address(dst_addr) and length(len -
copied) are huge page size aligned.

While this is ensured by:

    dst_start and len is huge page size aligned
    dst_addr equals to dst_start and increase huge page size each time
    copied increase huge page size each time

This means these warnings will never be triggered.

Link: http://lkml.kernel.org/r/20190927070032.2129-2-richardw.yang@linux.intel.com
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index c545ee84331debe6b70383fcdc14c7899900f2ed..07f44555fd03dafa24ecd9341bf41279063269cd 100644 (file)
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -242,10 +242,6 @@ retry:
                vm_shared = dst_vma->vm_flags & VM_SHARED;
        }
 
-       if (WARN_ON(dst_addr & (vma_hpagesize - 1) ||
-                   (len - copied) & (vma_hpagesize - 1)))
-               goto out_unlock;
-
        /*
         * If not shared, ensure the dst_vma has a anon_vma.
         */
@@ -259,7 +255,6 @@ retry:
                pte_t dst_pteval;
 
                BUG_ON(dst_addr >= dst_start + len);
-               VM_BUG_ON(dst_addr & (vma_hpagesize - 1));
 
                /*
                 * Serialize via hugetlb_fault_mutex