Excerpts from peterz@xxxxxxxxxxxxx's message of August 19, 2020 1:41 am: > On Tue, Aug 18, 2020 at 05:22:33PM +1000, Nicholas Piggin wrote: >> Excerpts from peterz@xxxxxxxxxxxxx's message of August 12, 2020 8:35 pm: >> > On Wed, Aug 12, 2020 at 06:18:28PM +1000, Nicholas Piggin wrote: >> >> Excerpts from peterz@xxxxxxxxxxxxx's message of August 7, 2020 9:11 pm: >> >> > >> >> > What's wrong with something like this? >> >> > >> >> > AFAICT there's no reason to actually try and add IRQ tracing here, it's >> >> > just a hand full of instructions at the most. >> >> >> >> Because we may want to use that in other places as well, so it would >> >> be nice to have tracing. >> >> >> >> Hmm... also, I thought NMI context was free to call local_irq_save/restore >> >> anyway so the bug would still be there in those cases? >> > >> > NMI code has in_nmi() true, in which case the IRQ tracing is disabled >> > (except for x86 which has CONFIG_TRACE_IRQFLAGS_NMI). >> > >> >> That doesn't help. It doesn't fix the lockdep irq state going out of >> synch with the actual irq state. The code which triggered this with the >> special powerpc irq disable has in_nmi() true as well. > > Urgh, you're talking about using lockdep_assert_irqs*() from NMI > context? > > If not, I'm afraid I might've lost the plot a little on what exact > failure case we're talking about. > Hm, I may have been a bit confused actually. Since your Fix TRACE_IRQFLAGS vs NMIs patch it might now work. I'm worried powerpc disables trace irqs trace_hardirqs_off() before nmi_enter() might still be a problem, but not sure actually. Alexey did you end up re-testing with Peter's patch or current upstream? Thanks, Nick
