rpc.rstatd on Linux 3.x series kernels fails to respond to requests; it writes the following to syslog and exits:
rpc.rstatd[76260]: dummy function, should never be called!
3.x uses the same interface as 2.6.x, only the version check has to be updated.
Patch
This updated patch also supports Linux kernel 4.x.
This updated patch also supports Linux kernel 5.x