powerpc/numa: Set numa_node for all possible cpus (a874f100) · Commits · 戴 / test

A Powerpc system with multiple possible nodes and with CONFIG_NUMA enabled always used to have a node 0, even if node 0 does not any cpus or memory attached to it. As per PAPR, node affinity of a cpu is only available once its present / online. For all cpus that are possible but not present, cpu_to_node() would point to node 0. To ensure a cpuless, memoryless dummy node is not online, powerpc need to make sure all possible but not present cpu_to_node are set to a proper node. Signed-off-by:

Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by:

Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200818081104.57888-2-srikar@linux.vnet.ibm.com

arch/powerpc/mm/numa.c

+15 −1

Original line number	Diff line number	Diff line
		@@ -507,6 +507,11 @@ static int numa_setup_cpu(unsigned long lcpu)
		int fcpu = cpu_first_thread_sibling(lcpu);
		int nid = NUMA_NO_NODE;

		if (!cpu_present(lcpu)) {
		set_cpu_numa_node(lcpu, first_online_node);
		return first_online_node;
		}

		/*
		* If a valid cpu-to-node mapping is already available, use it
		* directly instead of querying the firmware, since it represents
		@@ -944,9 +949,18 @@ void __init mem_topology_setup(void)

		reset_numa_cpu_lookup_table();

		for_each_present_cpu(cpu)
		for_each_possible_cpu(cpu) {
		/*
		* Powerpc with CONFIG_NUMA always used to have a node 0,
		* even if it was memoryless or cpuless. For all cpus that
		* are possible but not present, cpu_to_node() would point
		* to node 0. To remove a cpuless, memoryless dummy node,
		* powerpc need to make sure all possible but not present
		* cpu_to_node are set to a proper node.
		*/
		numa_setup_cpu(cpu);
		}
		}

		void __init initmem_init(void)
		{

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