Yes: KSplice had software patents - Oracle bought them. And
everyone knows what Oracle is like with software patents: aggressive!
I'm not clear what they actually cover, and can't look them up right now, but I'd thought they were specific on how KSplice in particular operates, both applying hotpatches and analysing the source to create them. I don't know whether they'd apply to anything else, or whether there is prior art, but they're an obvious landmine to be aware of and to avoid. So a simple fork wouldn't do unless it'd change the way it actually worked. A fresh approach was needed, and we seem to have two fresh approaches here.
I'm trusting they've been avoided here. They probably have, as this is much more general? The concept of hot patches are of course fine, people have been doing that for decades, and you can't patent concepts.
The lesson here: please don't patent stuff jn your open-source software, in case you wake up one day and got acquihired by Evil™.