Re: [RFC PATCH] powerpc/numa: reset node_possible_map to only node_online_map

From: David Rientjes <rientjes@google.com>
To: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
	Paul Mackerras <paulus@samba.org>,
	Anton Blanchard <anton@samba.org>, Tejun Heo <tj@kernel.org>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [RFC PATCH] powerpc/numa: reset node_possible_map to only node_online_map
Date: Thu, 5 Mar 2015 13:16:35 -0800 (PST)	[thread overview]
Message-ID: <alpine.DEB.2.10.1503051315270.25235@chino.kir.corp.google.com> (raw)
In-Reply-To: <20150305180549.GA29601@linux.vnet.ibm.com>

On Thu, 5 Mar 2015, Nishanth Aravamudan wrote:

> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index 0257a7d659ef..24de29b3651b 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -958,9 +958,17 @@ void __init initmem_init(void)
>  
>  	memblock_dump_all();
>  
> +	/*
> +	 * zero out the possible nodes after we parse the device-tree,
> +	 * so that we lower the maximum NUMA node ID to what is actually
> +	 * present.
> +	 */
> +	nodes_clear(node_possible_map);
> +
>  	for_each_online_node(nid) {
>  		unsigned long start_pfn, end_pfn;
>  
> +		node_set(nid, node_possible_map);
>  		get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
>  		setup_node_data(nid, start_pfn, end_pfn);
>  		sparse_memory_present_with_active_regions(nid);

This seems a bit strange, node_possible_map is supposed to be a superset 
of node_online_map and this loop is iterating over node_online_map to set 
nodes in node_possible_map.