From a874f1005ef5dfe53dfd8cda59a6600e89986ecd Mon Sep 17 00:00:00 2001
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Date: Tue, 18 Aug 2020 13:41:02 +0530
Subject: [PATCH] powerpc/numa: Set numa_node for all possible cpus
References: bsc#1171068 ltc#183935
Patch-mainline: v5.10-rc1
Git-commit: a874f1005ef5dfe53dfd8cda59a6600e89986ecd
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
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/mm/numa.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 5ddc83ba20f4..f63e1a41402f 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -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
@@ -944,8 +949,17 @@ 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)
--
2.28.0