For some time, I’ve seen these messages and been slightly bothered by them. Today, I found the solution.
can't re-use a leaf (geom_label)! can't re-use a leaf (geom_part_gpt)! module_register: module g_label already exists! Module g_label failed to register: 17 module_register: module g_part_gpt already exists! Module g_part_gpt failed to register: 17
Those messages appeared on the console while booting and were logged in /var/log/dmesg.boot. I was told, but I forget where, that this was because I was specifying modules which were already loaded.
Today I went to /boot/loader.conf and removed the following:
I rebooted the server. All came back fine. No more messages. Fixed.
NOTE: the original post also showed removing geom_eli_load and geom_mirror_load, which I believe would be incorrect.