mmap: remove unnecessary lock from __vma_link

There's no anon-vma related mangling happening inside __vma_link anymore
so no need of anon_vma locking there.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/mmap.c

@@ -452,12 +452,10 @@ static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 		spin_lock(&mapping->i_mmap_lock);
 		vma->vm_truncate_count = mapping->truncate_count;
 	}
-	vma_lock_anon_vma(vma);
 
 	__vma_link(mm, vma, prev, rb_link, rb_parent);
 	__vma_link_file(vma);
 
-	vma_unlock_anon_vma(vma);
 	if (mapping)
 		spin_unlock(&mapping->i_mmap_lock);