It seems mmap module is using inappropriate exception types. For example,

	if (! (PyString_Check(v)) ) {
		PyErr_SetString(PyExc_IndexError,
				"mmap slice assignment must be a string");
		return -1;
	}

I think this should be PyExc_TypeError.

		if (self->size >= pos && count > self->size - pos) {
			PyErr_SetString(PyExc_ValueError,
					"source or destination out of range");
			return NULL;

I think this is out of range, so PyExc_IndexError.

Of course, there is the case difficult to determine which exception is
suitable. For example, if Py_ssize_t is negative value, OverflowError or
IndexError?

Could someone please advise on the appropriate exception types for mmap.

Here's a patch.

It is uncomfortable changing exception types have been a published API for over a decade, so I'll leave this one open for a bit so that others can comment.

Most of the changes in the patch are correct and match their counterparts for lists and strings.  The TypeError for slice deletion was correct as-is (it matches del 'abc'[1]).  The IndexError on slice assignment may be correct as-is (I'll do more research).  The from ValueError to SystemError is questionable.  Otherwise, the patch looks to be mostly correct (I'll give it a more thorough review later).