Note that I don’t need a solution on this. This is for comments and seeing if other people have a similar problem.
I run a Fedora system as my file server and email server with a couple of btrfs arrays.
I recently upgraded it to Fedora 33, and it started to randomly freeze without putting any output in the systemd journal, and nothing on the console either, and it appeared to be completely unresponsive to the USB keyboard. So, I don’t have any debugging output to share.
But after I disabled zram it hasn’t done that since.
I’ve customized its memory settings quite a lot. Some of the interesting changes are
movablecore=8G on the kernel command line and running with strict memory commit. See:
/etc/sysctl.d/10-dirty.conf:# 512 MB /etc/sysctl.d/10-dirty.conf:vm.dirty_background_bytes = 536870912 /etc/sysctl.d/10-dirty.conf:# 4 GB /etc/sysctl.d/10-dirty.conf:vm.dirty_bytes = 4294967296 /etc/sysctl.d/10-dirty.conf:vm.dirty_writeback_centisecs = 500 /etc/sysctl.d/10-dirty.conf:vm.dirty_expire_centisecs = 6000 /etc/sysctl.d/20-max-maps.conf:vm.max_map_count = 262144 /etc/sysctl.d/20-overcommit.conf:vm.overcommit_ratio = 52 /etc/sysctl.d/20-overcommit.conf:vm.overcommit_memory = 2 [...snip...] /etc/sysctl.d/91-swappiness.conf:vm.swappiness=80 /etc/sysctl.d/91-swappiness.conf:vm.vfs_cache_pressure=1