open_file = open("file.txt", "r+b")
file_map = mmap.mmap(open_file, 0)
file_map.seek(offset)
file_map.write("foobar") # success
file_map.flush() # success
file_map.flush(offset, len("foobar")) # Fails with "errno 22"

This example passes correct arguments to mmap.flush(), yet it fails with errno 22. So the arguments are not valid on linux. If the bug cannot be fixed, then all reference to those two arguments should be removed from the code and documentation related to Linux.