[cyphar]

The core code behind kSplice/kGraft have been upstream since Linux 4.0 and both Red Hat and SUSE support it (in fact, many security patches are released this way). I believe that some less enterprise-y disros like Fedora and Ubuntu support it too.

The issue isn't whether it's supported, the problem is that live patching is limited in what it can patch (when functions are inlined it can become impossible to patch them and so on). So while a machine with 4 years uptime might be live patched there are some security issues that cannot be patched that way (for instance, the retpoline patches for Meltdown/Spectre require all function pointers to have different calling conventions and that requires a reboot).