2.1.something added a real console device, c 5 1. Using that, root can't log in until securetty is updated.
This bug should be reported to the Red Hat Rawhide release bug tracking system. This section is for stable release Red Hat only.
According to http://www.redhat.com/product.phtml/RH5020, RH 5.2 is supposed to be kernel 2.2 ready, isn't it? Does not that mean that all incompatibilities between new 2.1.x kernels and RH 5.2 should be considered RH 5.2 bugs?