Greg Kroah-Hartman has banned a US university from trying to mainline Linux kernel patches over intentionally submitting questionable code with security implications and other "experiments" in the name of research.
Stemming from a research paper where researchers from the University of Minnesota intentionally worked to stealthy introduce vulnerabilities into the mainline Linux kernel. They intentionally introduced use-after-free bugs into the kernel covertly for their research paper.
But even after this paper, there has been a new round of patches from University of Minnesota researchers that claim to come from "a new static analyzer" but without any real value to the patches. These new, questionable patches don't appear to have any real value -- for good or bad -- and at the very least are just wasting time by upstream developers. This has led Greg to calling them out and "banning" them from trying to contribute to the Linux kernel in the future.