On Fri, 29 Dec 2017, Linus Torvalds wrote: > Ok, so what does seem to be consistent for everybody is that > double-fault in the NMI backtrace. > > So the fact that the NMI always hits on a double-fault does make me > suspect that it's a infinite stream of double-faults, and that is > presumably also what causes the RCU timeout. As I've been fighting with recursive double-faults lately (backporting PTI to ancient kernels), I can tell you that this is not the symptom you'd be seeing in such case; recursive double fault pretty quickly overflows the interrupt stack and triple-faults. -- Jiri Kosina SUSE Labs