On Mon, 25 Jun 2018 09:39:51 -0700 Joel Fernandes <j...@joelfernandes.org> wrote:
> For whatever its worth, I made some notes of what I understood from reading > the code and old posts because I was sure I would otherwise forget > everything: > http://www.joelfernandes.org/linuxinternals/2018/06/15/rcu-dynticks.html Nice write up. I may point some people to this ;-) Anyway "complications due to nested NMIs (yes NMIs can nest!)" What arch allows for NMIs to nest. Because we don't let that happen on x86, and there's code that I know of that is called by NMIs that is not re-entrant, and can crash if we allow for NMIs to nest. For example "in_nmi()" will not show that we are in_nmi() if we allow for nesting of NMIs. It has a single bit that gets incremented when we enter NMI code, and cleared when we leave it. -- Steve
