Re: [2.6.20][PATCH] fix mempolicy error check on a system with memory-less-node

[Christoph Lameter <clameter@sgi.com>]

On Tue, 6 Feb 2007, KAMEZAWA Hiroyuki wrote:

> This means an access to NULL,here.
> ==
> unsigned slab_node(struct mempolicy *policy)
> {
>         case MPOL_BIND:
>                 /*
>                  * Follow bind policy behavior and start allocation at the
>                  * first node.
>                  */
>                 return zone_to_nid(policy->v.zonelist->zones[0]);
> }
> ==
> length of this zonelist was 0.
> It seems fixing a NULL access here is also O.K. 
> This patch is just an idea.

Hmmm... Remove the node from the node_online_map instead?

>  	}
> -	return nodes_subset(*nodes, node_online_map) ? 0 : -EINVAL;
> +	nodes_clear(node_with_memory);
> +	for_each_online_node(nd) {
> +		if (node_present_pages(nd))
> +			node_set(nd, node_with_memory);
> +	}
> +	return nodes_subset(*nodes, node_with_memory) ? 0 : -EINVAL;
>  }

Uhh. No loops here please. If we really need this then we need to have 
some sort of set operation here.