Details from top, free, /proc/###, ps do not match

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The memory usage summary from free, top, /proc/meminfo do not match the per process usage details in top, ps and /proc/####/. No matter how I add up VIRT, RES and SHR, I cannot find where my physical RAM is spent. Similarly, my buffer/cache does not say much. Please kindly help point out where that 26GB is spent.
Below are the details extracted from top sorted based on RES.

top - 17:58:57 up 7 days, 13:52, 2 users, load average: 0.17, 0.06, 0.06
Tasks: 322 total, 1 running, 321 sleeping, 0 stopped, 0 zombie
%Cpu(s): 0.3 us, 0.1 sy, 0.0 ni, 99.6 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 31931048 total, 450796 free, 26598920 used, 4881332 buff/cache
KiB Swap: 15724540 total, 15724540 free, 0 used. 4748272 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM
10548 oracle 20 0 4733664 321964 16532 S 0.3 1
9636 root 20 0 4208780 231296 13876 S 0 0.7
9879 root 20 0 689076 158480 10336 S 2.3 0.5
18109 root 20 0 522436 78064 8700 S 0 0.2
8916 root 20 0 304644 69744 9868 S 0 0.2
8234 root 20 0 705372 45028 5160 S 0 0.1
4181 root 20 0 92436 38980 38624 S 0 0.1
8927 root 20 0 273888 30268 22064 S 0 0.1
27441 root 20 0 318388 24472 8344 S 0 0.1
9432 root 20 0 776240 22828 17480 S 0 0.1
8919 root 20 0 574088 17436 6104 S 0 0.1
10033 oracle 20 0 170424 15684 2780 S 0 0
9601 root 20 0 62020 15280 6220 S 0 0
9621 root 20 0 62020 15280 6220 S 0 0
9622 root 20 0 62020 15280 6220 S 0 0
9623 root 20 0 62020 15280 6220 S 0 0
9624 root 20 0 62020 15280 6220 S 0 0
9625 root 20 0 62020 15280 6220 S 0 0
9626 root 20 0 62020 15280 6220 S 0 0
9627 root 20 0 62020 15280 6220 S 0 0
8240 polkitd 20 0 617168 14256 5136 S 0 0
8272 root 20 0 483652 9880 7116 S 0 0
8921 root 20 0 373636 8704 7500 S 0 0
9224 root 20 0 394448 8024 5752 S 0 0
4231 root rt 0 587312 7848 6340 S 0 0
20957 root 20 0 350476 6716 4628 S 0 0
1 root 20 0 193444 6416 2636 S 0 0
9336 mfe 20 0 138160 6268 4844 S 0 0
8230 root 20 0 228232 5804 3876 S 0 0
1732 root 20 0 156640 5764 4440 S 0 0
9341 root 20 0 244428 5504 3924 S 0 0
20916 root 20 0 156652 5460 4144 S 0 0
8232 root 20 0 225724 4816 3340 S 0 0
8922 root 20 0 112756 4344 3312 S 0 0
1753 cupdusr 20 0 116628 3404 1800 S 0 0
9043 root 20 0 164800 3244 2332 S 0 0
8242 root 20 0 90392 3212 2348 S 0 0
20935 cupdusr 20 0 116496 3180 1676 S 0 0
12646 root 20 0 92820 2752 824 S 0 0
8245 dbus 20 0 60368 2680 1884 S 0 0
17567 cupdusr 20 0 162276 2576 1624 R 0 0
21113 cupdusr 20 0 162268 2544 1600 S 0.7 0
8967 zabbix 20 0 83360 2472 1500 S 0 0
8968 zabbix 20 0 83360 2472 1500 S 0 0
8969 zabbix 20 0 83360 2472 1500 S 0 0
20933 cupdusr 20 0 156652 2440 1124 S 0.3 0
1752 cupdusr 20 0 156640 2436 1112 S 0 0
8233 root 20 0 24492 2404 1732 S 0 0
9196 root 20 0 185480 2124 1392 S 0 0
8970 zabbix 20 0 83368 2092 1148 S 0 0
12835 smmsp 20 0 84120 2052 520 S 0 0
4236 root 20 0 44616 2028 1340 S 0 0
9490 chrony 20 0 103076 1848 1456 S 0 0
8241 root 20 0 26484 1844 1436 S 0 0
8966 zabbix 20 0 83236 1820 988 S 0 0
9620 root 20 0 116216 1768 1132 S 0 0
9475 root 20 0 126284 1632 1004 S 0 0
24822 rpc 20 0 73648 1548 812 S 0 0
8244 root 20 0 21664 1348 988 S 0 0
8208 root 16 -4 62044 1292 660 S 0 0
8947 zabbix 20 0 83236 1272 444 S 0 0
8287 root 20 0 25904 964 760 S 0 0
8303 root 20 0 110092 860 732 S 0 0
8229 libstor+ 20 0 8576 828 676 S 0 0
9655 root 20 0 107968 636 484 S 0 0
8277 root 20 0 6608 284 144 S 0 0
2 root 20 0 0 0 0 S 0 0
3 root 20 0 0 0 0 S 0 0
5 root 0 -20 0 0 0 S 0 0
7 root rt 0 0 0 0 S 0 0
8 root 20 0 0 0 0 S 0 0

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