pmap showing almost DOUBLE memory usage than before, more than top total
Sometime in the last several months, pmap started reporting much (sometimes near double) larger memory usage than I am used to seeing. In fact, the sum total of pmap -d over several separate firefox processes (*) is now larger than the TOTAL memory usage shown by top. It used to be that tallying up the firefox memory usage was always smaller than the top total memory usage.
Has anyone seen anything like this? Could it be that a newer kernel version has changed the format or data definition in some /proc file that pmap reads? I could provide some specific example numbers if needed.
(*) NOTE: these are completely separate firefox instances, unrelated processes
(**) Operating system being used: PRETTY_NAME="Ubuntu 20.04.2 LTS" Linux version 5.4.0-72-generic (buildd@lcy01-amd64-019) (gcc version 9.3.0 (Ubuntu 9.3.0-17ubuntu1~20.04)) #80 (closed)-Ubuntu SMP Mon Apr 12 17:35:00 UTC 2021