New Kernel Live Patching Combines kGraft & Kpatch

Back in February SUSE unveiled a new means of live Linux kernel patching, kGraft, compared to the existing Ksplice. One month later, Red Hat unveiled their own solution that happened to be under development at the same time, Kpatch. Since both of them have been out, both have pursued mainline interests but neither one accepted upstream yet. Now a new live kernel patching solution is out that tries to take the best of both worlds.

The newest kernel live patching solution uses an ftrace-based mechanism and kernel interface for doing live patching of the kernel with kernel module functions. According to Seth Jennings who posted the patches, "it represents the greatest common functionality set between kpatch and kGraft." Seth Jennings is a Red Hat developer. This new kernel live patching can accept kernel patches built by both kGraft and Kpatch. This design came out of the live patching mini-conference at the Linux Plumbers' Conference last month.

This new approach is just over one thousand lines of code in the kernel. This new live kernel patching mechanism can be found via this patch series. Perhaps this path -- or kGraft or Kpatch -- will be figured out in time for the Linux 3.19 merge window.