Re: [BUG] i386 2.6.18 cpu_up: attempt to bring up CPU 4 failed : kernel BUG at mm/slab.c:2698!

[Andrew Morton <akpm@osdl.org>]

On Fri, 22 Sep 2006 12:44:18 -0700
keith mannthey <kmannth@us.ibm.com> wrote:

> 3. Flat mode i386 numa on a real numa system is broken.  If there is
> only 1 node in the system cpus should think they are apart of some other
> node.     Patch below.  
> 
> 
> 
>   If cases where a real numa system boots the Flat numa option make sure
> the cpus don't claim to be apart on a non-existent node.
> 
> 
> Signed-off-by: Keith Mannthey <kmannth@us.ibm.com>
> 
> --- linux-2.6.18/arch/i386/kernel/smpboot.c	2006-09-19
> 20:42:06.000000000 -0700
> +++ linux-2.6.18-workes/arch/i386/kernel/smpboot.c	2006-09-21
> 21:57:55.000000000 -0700
> @@ -642,9 +642,13 @@
>  {
>  	int cpu = smp_processor_id();
>  	int apicid = logical_smp_processor_id();
> -
> +	int node = apicid_to_node(apicid);
> +	
> +	if (!node_online(node))
> +		node = first_online_node;
> +	
>  	cpu_2_logical_apicid[cpu] = apicid;
> -	map_cpu_to_node(cpu, apicid_to_node(apicid));
> +	map_cpu_to_node(cpu, node);
>  }
>  
>  static void unmap_cpu_to_logical_apicid(int cpu)

This clashes with your
convert-i386-summit-subarch-to-use-srat-info-for-apicid_to_node-calls.patch.

I fixed it thusly:

static void map_cpu_to_logical_apicid(void)
{
	int cpu = smp_processor_id();
	int apicid = logical_smp_processor_id();
	int node = apicid_to_node(hard_smp_processor_id());

	if (!node_online(node))
		node = first_online_node;

	cpu_2_logical_apicid[cpu] = apicid;
	map_cpu_to_node(cpu, node);
}