mm/memory.c: update comment in unmap_single_vma()

The described issue now occurs inside mmap_region().  And unfortunately
is still valid.
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory.c

@@ -1320,9 +1320,9 @@ static void unmap_single_vma(struct mmu_gather *tlb,
 			 * It is undesirable to test vma->vm_file as it
 			 * should be non-null for valid hugetlb area.
 			 * However, vm_file will be NULL in the error
-			 * cleanup path of do_mmap_pgoff. When
+			 * cleanup path of mmap_region. When
 			 * hugetlbfs ->mmap method fails,
-			 * do_mmap_pgoff() nullifies vma->vm_file
+			 * mmap_region() nullifies vma->vm_file
 			 * before calling this function to clean up.
 			 * Since no pte has actually been setup, it is
 			 * safe to do nothing in this case.