rt_secondary+0x13/0xeb The reason is that the bit of node 2 was not set at numa_nodes_parsed. numa_nodes_parsed is set by only acpi_numa_processor_affinity_init / acpi_numa_x2apic_affinity_init. Thus even if hot-added memory which is same PXM as hot-added CPU is written in ACPI SRAT Table, if the hot-added CPU is not written in ACPI SRAT table, numa_nodes_parsed is not set. But according to ACPI Spec Rev 5.0, it says about ACPI SRAT table as follows: This optional table provides information that allows OSPM to associate processors and memory ranges, including ranges of memory provided by hot-added memory devices, with system localities / proximity domains and clock domains. It means that ACPI SRAT table only provides information for CPUs present at boot time and for memory including hot-added memory. So hot-added memory is written in ACPI SRAT table, but hot-added CPU is not written in it. Thus numa_nodes_parsed should be set by not only acpi_numa_processor_affinity_init / acpi_numa_x2apic_affinity_init but also acpi_numa_memory_affinity_init for the case. Additionally, if system has cpuless memory node, acpi_numa_processor_affinity_init / acpi_numa_x2apic_affinity_init cannot set numa_nodes_parseds since these functions cannot find cpu description for the node. In this case, numa_nodes_parsed needs to be set by acpi_numa_memory_affinity_init. Signed-off-by: Yasuaki Ishimatsu Acked-by: David Rientjes Acked-by: KOSAKI Motohiro Cc: liuj97@gmail.com Cc: kosaki.motohiro@gmail.com Link: http://lkml.kernel.org/r/4FCC2098.4030007@jp.fujitsu.com [ merged it ] Signed-off-by: Ingo Molnar 6{x