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SubjectRe: [PATCH 1/2] arm64: avoid alloc memory on offline node
Michal Hocko <> 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.



-- >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))

- 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",
- return;
- }

pxm = pa->proximity_domain;
node = acpi_map_pxm_to_node(pxm);
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