Our current process memory reports, are not coping with memory sizes in excess of 4GB, due to their reliance on an outdates system call to mallinfo().
As a result our stats line, e.g.:
SYS: PU= 31% MU= 92% MAL=2786699248 MMP=2785816576 SBK=882672 TOT=2728120K RAM=91734904K SWP=4154672K
can't be relied on for MAL/ MMP/SBK/TOT.
I think malloc_info() is the newer method that should be being used : http://man7.org/linux/man-pages/man3/malloc_info.3.html
RAM/SWAP are global and read from /proc/meminfo.
They are read with jdebug method getMemUsage(), which reports results as unsigned, the values represent #'s of K.
So that is less of a problem and won't rollover any time soon, but should be updated to handle 64bit also.