Linux can use kpatch to upgrade the kernel while it is running. The difficult part is writing and validating the actual patch. I recall that the only people wr

Linux can use kpatch to upgrade the kernel while it is running. The difficult part is writing and validating the actual patch. I recall that the only people writing kpatches charge a lot of money for them and only provide them to their paying support customers. Then all of the free software people complain loudly. Yet, you don't see THEM writing (and TESTING) these functions to update in-kernel data structures in place.