In mmapmodule.c a function mmap_move_method, use unsigned variables dest, src, cnt, as signed:
unsigned long dest, src, cnt;
...
if (cnt <0 | | (cnt + dest) <cnt | | (cnt + src) <cnt | |
            src <0 | | src> self-> size | | (src + cnt)> self-> size | |
            dest <0 | | dest> self-> size | | (dest + cnt)> self-> size)