Being aware using zram-swap is not a default feature on the CentOS Userland for armv7hl, Still want to share the problem I ran in to. I turns out the arm 32bit kernel with large memory support OOPS if zram-swap is deployed if the system has more than 4GB ram. This issue seems to be addressed (verry recently) in kernel 5.4.81 (1) As mentioned this is verry recently, version 5.4.81 is just 12 day's old.. However if there is a testbuild of this rpi2-kernel4: I'm eager to test it 😉 1) https://github.com/raspberrypi/linux/commit/1bef5f25a69234613b92a0e2456870fee4a57efc