[PATCH] x86: fix system without memory on node0

[Yinghai Lu]

Jack found that crash with doesn't have memory on node0.

it turns out with per_cpu changeset, node_number for BSP will be alway 0,
and it is consistent to cpu_to_node() that is to near node already.
aka when numa_set_node() for node0 is called early before per_cpu area is
setup

try to set the node_number for boot cpu, after we get per_cpu area setup.

[ Impact: fix crashing on memoryless node 0]

Reported-by: Jack Steiner <steiner@xxxxxxx>
Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>

---
 arch/x86/kernel/setup_percpu.c |    8 ++++++++
 1 file changed, 8 insertions(+)

Index: linux-2.6/arch/x86/kernel/setup_percpu.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/setup_percpu.c
+++ linux-2.6/arch/x86/kernel/setup_percpu.c
@@ -423,6 +423,14 @@ void __init setup_per_cpu_areas(void)
 	early_per_cpu_ptr(x86_cpu_to_node_map) = NULL;
 #endif
 
+#if defined(CONFIG_X86_64) && defined(CONFIG_NUMA)
+	/*
+	 * make sure boot cpu node_number is right, when boot cpu is on the
+	 * node that doesn't have mem installed
+	 */
+	per_cpu(node_number, boot_cpu_id) = cpu_to_node(boot_cpu_id);
+#endif
+
 	/* Setup node to cpumask map */
 	setup_node_to_cpumask_map();
 
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