Until Red Hat starts to add backports or fixes for customers that don't get push back upstream. Then when X+1 gets to RHEL it's missing all the previous RHEL only updates (some not backport related).
Maybe they're reading this comment right now, hi!
Kernelcare has given me 48 hotfixes on a 3.10 kernel that I booted last year.
kcarectl --patch-info | awk '/^kpatch-name/{print ++n};{print}'
....
48
kpatch-name: 3.10.0/proc-restrict-pagemap-access-1062.patch
kpatch-description: Restrict access to pagemap/kpageflags/kpagecount
kpatch-kernel:
kpatch-cve:
kpatch-cvss:
kpatch-cve-url: http://googleprojectzero.blogspot.ru/2015/03/exploiting-dram-rowhammer-bug-to-gain.html
kpatch-patch-url:
uname: 3.10.0-1160.25.1.el7Ksplice (Oracle) was first, followed by kgraft (Suse), and kpatch (RedHat).
According to the article below, kpatch is x86/64 only, uses ftrace, provides runtime patches only until the next minor kernel release on a standard license, does not address all CVEs, and cannot be used with "SystemTop or kprobe."
"KernelCare has no such limitations."
https://blog.kernelcare.com/competitors/kpatch-overview-of-e...
Ksplice was done by MIT students, not Oracle. I used it long before Oracle bought it, initially with my own patches (and actually after that as a "legacy" customer). kpatch isn't just x86_64; it's in at least ppc64le RHEL 7, although not for the "alt kernel" on the POWER9 systems I use.
I don't know whether it's the case, but their comparison rather suggests Kernelcare is based on Ksplice.
Anyway, RHEL kernels have various features backported to the vanilla version on which it was originally based, not just security patches, which probably makes the job harder. It is a major effort.
Very little dev effort is working on anything cool, and very little of the code for cool projects isn't kinda boring and normal.