Re: [PATCH 6/6] Filter based on a nodemask as well as a gfp_mask

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

Hi 

> The MPOL_BIND policy creates a zonelist that is used for allocations
> controlled by that mempolicy. As the per-node zonelist is already being
> filtered based on a zone id, this patch adds a version of __alloc_pages()
> that takes a nodemask for further filtering. This eliminates the need
> for MPOL_BIND to create a custom zonelist.
> 
> A positive benefit of this is that allocations using MPOL_BIND now use the
> local node's distance-ordered zonelist instead of a custom node-id-ordered
> zonelist.  I.e., pages will be allocated from the closest allowed node with
> available memory.

Great.
this is not only clean up, but also great mempolicy improvement.


> -/* Generate a custom zonelist for the BIND policy. */
> -static struct zonelist *bind_zonelist(nodemask_t *nodes)
> +/* Check that the nodemask contains at least one populated zone */
> +static int is_valid_nodemask(nodemask_t *nodemask)
>  {
(snip)
> +	for_each_node_mask(nd, *nodemask) {
> +		struct zone *z;
> +
> +		for (k = 0; k <= policy_zone; k++) {
> +			z = &NODE_DATA(nd)->node_zones[k];
> +			if (z->present_pages > 0)
> +				return 1;

could we use populated_zone()?


-kosaki

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