--- x/fs/ntfs3/file.c
+++ y/fs/ntfs3/file.c
@@ -365,7 +365,10 @@ static int ntfs_file_mmap(struct file *f
 		}
 
 		if (ni->i_valid < to) {
-			inode_lock(inode);
+			if (!inode_trylock(inode)) {
+				err = -EDEADLK;
+				goto out;
+			}
 			err = ntfs_extend_initialized_size(file, ni,
 							   ni->i_valid, to);
 			inode_unlock(inode);