Linux 5.1 Livepatching Lands Atomic Replace / Cumulative Patches Support

With the in-development Linux 5.1 is a big step forward to the kernel's live-patching infrastructure for this functionality that allows primarily applying security updates against the running kernel without the need for reboots.

The big step forward with Linux 5.1 live-patching is now the ability to properly handle "cumulative patches" or a series of patches that depend upon the prior patches, which can now be properly handled with the infrastructure's new atomic-replace functionality. This eases the roll-out of live patches implemented over the course of multiple patches with ordering/stacking and also recovering performance for functions no longer being patched.

The atomic replace / cumulative patch support has been a long time coming and ended up going through more than 15 revisions before all upstream developers being satisfied.

All of the live-patching code for Linux 5.1 can be found via this pull request.