Google is a corporation. The linux kernel is [by implication] developed and maintained by Linus. Please don't do this. If there are race conditions, fix them following the process of kernel.org.
Something like 80+% of commits to the kernel are by people paid to work on Linux (Google employees among them). This is just part of the Linux development model and has been for a long time.
Where in the 'linux process' does it mandate that 'code MUST NOT be made available on GitHub'?
Google basically announced their project and published the code. That's it. In their email to the LKML (https://lkml.org/lkml/2019/9/20/394) they specifically mention:
In the coming weeks we're planning to:
* Attempt to send fixes for some races upstream […]
There are a few open questions:
* How/when to upstream KCSAN?
So they intend to follow the standard contribution process of sending fixes upstream.