On Mon, Feb 24, 2020 at 11:10:50AM +0100, Peter Zijlstra wrote: > On Fri, Feb 21, 2020 at 10:08:43PM -0500, Joel Fernandes wrote: > > On Fri, Feb 21, 2020 at 02:34:17PM +0100, Peter Zijlstra wrote: > > > nmi_enter() does lockdep_off() and hence lockdep ignores everything. > > > > > > And NMI context makes it impossible to do full IN-NMI tracking like we > > > do IN-HARDIRQ, that could result in graph_lock recursion. > > > > The patch makes sense to me. > > > > Reviewed-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx> > > > > NOTE: > > Also, I was wondering if we can detect the graph_lock recursion case and > > avoid doing anything bad, that way we enable more of the lockdep > > functionality for NMI where possible. Not sure if the suggestion makes sense > > though! > > Yeah, I considered playing trylock games, but figured I shouldn't make > it more complicated that it needs to be. Yes, I agree with you. Thanks. - Joel
