On Tue, Jun 19, 2018 at 01:52:16PM +0100, Punit Agrawal wrote: > Michal Hocko <mhocko@xxxxxxxxxx> writes: > > > On Tue 19-06-18 20:03:07, Xie XiuQi wrote: > > [...] > >> I tested on a arm board with 128 cores 4 numa nodes, but I set CONFIG_NR_CPUS=72. > >> Then node 3 is not be created, because node 3 has no memory, and no cpu. > >> But some pci device may related to node 3, which be set in ACPI table. > > > > Could you double check that zonelists for node 3 are generated > > correctly? > > The cpus in node 3 aren't onlined and there's no memory attached - I > suspect that no zonelists are built for this node. > > We skip creating a node, if the number of SRAT entries parsed exceeds > NR_CPUS[0]. This in turn prevents onlining the numa node and so no > zonelists will be created for it. > > I think the problem will go away if the cpus are restricted via the > kernel command line by setting nr_cpus. > > Xie, can you try the below patch on top of the one enabling memoryless > nodes? I'm not sure this is the right solution but at least it'll > confirm the problem. This issue looks familiar (or at least related): git log d3bd058826aa The reason why the NR_CPUS guard is there is to avoid overflowing the early_node_cpu_hwid array. IA64 does something different in that respect compared to x86, we have to have a look into this. Regardless, AFAICS the proximity domains to nodes mappings should not depend on CONFIG_NR_CPUS, it seems that there is something wrong in that in ARM64 ACPI SRAT parsing. Lorenzo > > Thanks, > Punit > > [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/kernel/acpi_numa.c?h=v4.18-rc1#n73 > > -- >8 -- > diff --git a/arch/arm64/kernel/acpi_numa.c b/arch/arm64/kernel/acpi_numa.c > index d190a7b231bf..fea0f7164f1a 100644 > --- a/arch/arm64/kernel/acpi_numa.c > +++ b/arch/arm64/kernel/acpi_numa.c > @@ -70,11 +70,9 @@ void __init acpi_numa_gicc_affinity_init(struct acpi_srat_gicc_affinity *pa) > if (!(pa->flags & ACPI_SRAT_GICC_ENABLED)) > return; > > - if (cpus_in_srat >= NR_CPUS) { > + if (cpus_in_srat >= NR_CPUS) > pr_warn_once("SRAT: cpu_to_node_map[%d] is too small, may not be able to use all cpus\n", > NR_CPUS); > - return; > - } > > pxm = pa->proximity_domain; > node = acpi_map_pxm_to_node(pxm);
