On 29/05/18 18:08, Robin Murphy wrote: > On 29/05/18 16:51, Geert Uytterhoeven wrote: >> Hi Will, >> >> On Tue, May 29, 2018 at 5:08 PM, Will Deacon <will.deacon@xxxxxxx> wrote: >>> On Tue, May 29, 2018 at 02:18:40PM +0100, Sudeep Holla wrote: >>>> On 29/05/18 12:56, Geert Uytterhoeven wrote: >>>>> On Tue, May 29, 2018 at 1:14 PM, Sudeep Holla >>>>> <sudeep.holla@xxxxxxx> wrote: >>>>>> On 29/05/18 11:48, Geert Uytterhoeven wrote: >>>>>>> System supend still works fine on systems with big cores only: >>>>>>> >>>>>>> R-Car H3 ES1.0 (4xCA57 (4xCA53 disabled in firmware)) >>>>>>> R-Car M3-N (2xCA57) >>>>>>> >>>>>>> Reverting this commit fixes the issue for me. >>>>>> >>>>>> I can't find anything that relates to system suspend in these patches >>>>>> unless they are messing with something during CPU hot plug-in back >>>>>> during resume. >>>>> >>>>> It's only the last patch that introduces the breakage. >>>>> >>>> >>>> As specified in the commit log, it won't change any behavior for DT >>>> systems if it's non-NUMA or single node system. So I am still wondering >>>> what could trigger this regression. >>> >>> I wonder if we're somehow giving an uninitialised/invalid NUMA >>> configuration >>> to the scheduler, although I can't see how this would happen. >>> >>> Geert -- if you enable CONFIG_DEBUG_PER_CPU_MAPS=y and apply the diff >>> below >>> do you see anything shouting in dmesg? >> >> Thanks, but unfortunately it doesn't help. >> I added some debug code to print cpumask, but so far I don't see anything >> suspicious. > > Do you have CONFIG_NUMA enabled? On a hunch I've managed to reproduce > what looks like the same thing on a Juno board with NUMA=n; going in > with external debug it seems to be stuck in the loop in > init_sched_groups_capacity(), with an approximate stack trace of: > > > init_sched_groups_capacity() > partition_sched_domains() > cpuset_cpu_active() > sched_cpu_activate() > cpuhp_invoke_callback() > cpuhp_thread_fn() > > My hunch is based on the fact that it looks like we can, under the right > circumstances, end up with default_topology picking up cpu_online_mask > as a sibling mask via cpu_coregroup_mask(), and given the great > coincidence that that's going to change when hotplugging out CPUs on > suspend, things might not react too well to that. Things also look to go > utterly haywire once into a full-blown systemd userspace with cpuidle, > but I haven't got a clear picture of that yet. > Yes, I too observed the same. I was able to suspend resume if I have cpuidle disabled. -- Regards, Sudeep -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
