The things described at that link cannot be fixed in any simple way.

There it is said that Ginux does not implement mutual exclusion in the right way for a multiprocessor.

To implement this correctly and in a way that ensures high performance even on CPUs with hundreds of cores is one of the most difficult parts of an operating system kernel, much more difficult than just implementing the system call interfaces, to enable a user program to run.

Other point is that Ginux is vulnerable to some races caused by interrupts, which is again something difficult to get right in an operating system kernel, unless you copy exactly the corresponding code from the Linux kernel.