linux – High process memory usage (VmRSS) on rocky 8 vs. centos 7.7 for essentially everything

We’re migrating some servers from centos 7.7ish to Rocky linux 8, and we’re finding just about every process is using 20-50% more memory, causing machines to lock up.

For example, sh on centos:

# sh -c 'egrep "VmRSS|VmSwap" /proc/$$/status'
VmRSS:       664 kB
VmSwap:        0 kB

vs. rocky:

# sh -c 'egrep "VmRSS|VmSwap" /proc/$$/status'
VmRSS:      1136 kB
VmSwap:        0 kB

That’s just a simple example; httpd, nginx, postgres processes all have large increases, although the exact amount varies from around 20% to 50%, on identical hardware.

Does anyone have suggestions for what to look at to debug this? Some /proc settings that we might look at?

Kernels report:
centos: 3.10.0-1160.62.1.el7.x86_64
rocky: 4.18.0-348.12.2.el8_5.x86_64