On 10/14/16 17:42, Lorenzo Pieralisi wrote: > On Fri, Oct 14, 2016 at 05:27:58PM +0200, Laszlo Ersek wrote: >> On 10/14/16 17:01, Laszlo Ersek wrote: >> >>> Maybe the code I >>> tried to analyze in this email was never *meant* to associate CPU#0 with >>> any NUMA node at all (not even node 0); instead, other code -- for >>> example code removed by 7ba5f605f3a0 -- was meant to perform that >>> association. >> >> Staring a bit more at the code, this looks very likely; in >> acpi_map_gic_cpu_interface() we have >> >>> /* Check if GICC structure of boot CPU is available in the MADT */ >>> if (cpu_logical_map(0) == hwid) { >>> if (bootcpu_valid) { >>> pr_err("duplicate boot CPU MPIDR: 0x%llx in MADT\n", >>> hwid); >>> return; >>> } >>> bootcpu_valid = true; >>> return; >>> } >> >> which means that this callback function (for parsing the GICC >> structures in the MADT) expects to find the boot processor as well. >> >> Upon finding the boot processor, we set bootcpu_valid to true, and >> that's it -- no association with any NUMA node, and no incrementing of >> "cpu_count". > > Yes, because that's to check the MADT contains the boot cpu hwid. > > Does this help (compile tested only) ? > > -- >8 -- > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index d3f151c..8507703 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -544,6 +544,7 @@ static int __init smp_cpu_setup(int cpu) > return; > } > bootcpu_valid = true; > + early_map_cpu_to_node(0, acpi_numa_get_nid(0, hwid)); > return; > } > >
Your patch applies to the tree at v4.8-14604-g29fbff8698fc, but the function the hunk modifies is not smp_cpu_setup(), it is acpi_map_gic_cpu_interface(): > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index d3f151cfd4a1..8507703dabe4 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -544,6 +544,7 @@ acpi_map_gic_cpu_interface(struct > acpi_madt_generic_interrupt *processor) > return; > } > bootcpu_valid = true; > + early_map_cpu_to_node(0, acpi_numa_get_nid(0, hwid)); > return; > } > Anyway, your patch works with both the two-node NUMA configuration Drew suggested for testing, and with the single-node config that I originally used for the bisection. Therefore: Tested-by: Laszlo Ersek <ler...@redhat.com> Reported-by: Laszlo Ersek <ler...@redhat.com> Thank you very much for the quick bugfix! And, I think your patch (when you send it for real) should carry Fixes: 7ba5f605f3a0d9495aad539eeb8346d726dfc183 too, because it supplies the cpu#0<->node#xxx association that 7ba5f605f3a0 removed not just for DT, but also for ACPI. Cheers! Laszlo