I couldn’t figure out which process is holding the memory.

I got below result when I run free -h.

[root@ip-10-56-92-33 ~]# free -h
              total        used        free      shared  buff/cache   available
Mem:            61G         55G        1.1G         98M        5.0G        5.4G
Swap:            0B          0B          0B

I got below result when I run ps_mem.

[root@ip-10-56-107-50 ~]# /usr/local/bin/ps_mem
 Private  +   Shared  =  RAM used       Program

<deducted>
---------------------------------
                          8.2 GiB
=================================

There is a discrepancy between used memory 55G and total of running processes 8.2G.

Is there a way to find the root cause of which process is allocating the huge amount of memory?