Live Kernel Patching has been around for about 20 years[-1] now.

Red Hat Enterprise Linux[1] and Oracle (Enterprise Linux) Unbreakable Linux[2] both use it as a selling point.

This feature is still a bit ad hoc because, in most setups, rebooting a system isn't a huge burden and is much simpler than using boutique commands to live-patch it.

[-1] https://en.wikipedia.org/wiki/Ksplice

[0] https://www.ksplice.com/

[1] https://www.redhat.com/en/topics/linux/what-is-linux-kernel-...

[2] https://docs.oracle.com/en/learn/ol-ksplice/