[R] What is the meaning of "segfault 'memory not mapped' " ?

[Ubuntu.Diego]

I'm trying to get some "easy coding" to reproduce the error. In the
meantime I have R code that run for 20 or more hours and suddenly i got
a "segfault 'memory not mapped'" error. I have to clarify that the error
not alway occurs and sometimes the process end satisfactorily. The
process is basically a search using an MCMC strategy, sometimes the
algorithm converge and stops others I got the error message. I was
wondering if it could be meaning that I run out of RAM.
Thanks

PS: I don't want to submit code that maybe after 48 hours of running
still don't generate the error.