mm/mmap.c: don't unlock VMAs in remap_file_pages()

Since this call uses MAP_FIXED, do_mmap() will munlock the necessary
range.  There is also an error in the loop test expression which will
evaluate as false and the loop body has never execute.

Link: https://lkml.kernel.org/r/20210223235010.2296915-1-Liam.Howlett@Oracle.comSigned-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/mmap.c

@@ -3029,25 +3029,9 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 
 	flags &= MAP_NONBLOCK;
 	flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
-	if (vma->vm_flags & VM_LOCKED) {
-		struct vm_area_struct *tmp;
+	if (vma->vm_flags & VM_LOCKED)
 		flags |= MAP_LOCKED;
 
-		/* drop PG_Mlocked flag for over-mapped range */
-		for (tmp = vma; tmp->vm_start >= start + size;
-				tmp = tmp->vm_next) {
-			/*
-			 * Split pmd and munlock page on the border
-			 * of the range.
-			 */
-			vma_adjust_trans_huge(tmp, start, start + size, 0);
-
-			munlock_vma_pages_range(tmp,
-					max(tmp->vm_start, start),
-					min(tmp->vm_end, start + size));
-		}
-	}
-
 	file = get_file(vma->vm_file);
 	ret = do_mmap(vma->vm_file, start, size,
 			prot, flags, pgoff, &populate, NULL);