Unaccountable memory usage in the s390x guest machine running on the (z/VM) hypervisor

Issue

• Unable to account for memory usage in the s390x guest machine running on the (z/VM) hypervisor. The memory usage in the guest machine is high. However, total memory usage from user-space processes is low.

The crash built-in "kmem -i" command shows that the total memory usage in the system is 53.6 GiB.

crash> mach 
       MACHINE TYPE: s390x    

crash> kmem -i
                 PAGES        TOTAL      PERCENTAGE
    TOTAL MEM  14121948      53.9 GB         ----
         FREE     60649     236.9 MB    0% of TOTAL MEM
         USED  14061299      53.6 GB   99% of TOTAL MEM  <<< - - -  
       SHARED      7780      30.4 MB    0% of TOTAL MEM
      BUFFERS       329       1.3 MB    0% of TOTAL MEM
       CACHED     30211       118 MB    0% of TOTAL MEM
         SLAB    103278     403.4 MB    0% of TOTAL MEM

   TOTAL HUGE         0            0         ----
    HUGE FREE         0            0    0% of TOTAL HUGE

   TOTAL SWAP   4112446      15.7 GB         ----
    SWAP USED   4112382      15.7 GB   99% of TOTAL SWAP   
    SWAP FREE        64       256 KB    0% of TOTAL SWAP

 COMMIT LIMIT  11173420      42.6 GB         ----
    COMMITTED   2919748      11.1 GB   26% of TOTAL LIMIT

The crash built-in "ps" command shows that the total memory usage from the user space is 32.79 GiB.

crash> ps -u -G | sed 's/>//g' | awk '{ total += $8 } END { printf "Total RSS of user-mode: %.02f GiB\n", total/2^20 }'
Total RSS of user-mode: 32.79 GiB

~20 GiB of memory is unaccountable.

• How to determine the memory reserved by the cooperative memory manager module [cmm] from vmcore?
• How to determine the memory reserved to the cooperative memory manager module [cmm] from running system?