On Fri, 9 Nov 2007, Mel Gorman wrote:

 struct page * fastcall
 __alloc_pages(gfp_t gfp_mask, unsigned int order,
 		struct zonelist *zonelist)
 {
+	/*
+	 * Use a temporary nodemask for __GFP_THISNODE allocations. If the
+	 * cost of allocating on the stack or the stack usage becomes
+	 * noticable, allocate the nodemasks per node at boot or compile time
+	 */
+	if (unlikely(gfp_mask & __GFP_THISNODE)) {
+		nodemask_t nodemask;

Hmmm.. This places a potentially big structure on the stack. nodemask can 
contain up to 1024 bits which means 128 bytes. Maybe keep an array of 
gfp_thisnode nodemasks (node_nodemask?) and use node_nodemask[nid]?

+
+		return __alloc_pages_internal(gfp_mask, order,
+			zonelist, nodemask_thisnode(numa_node_id(), &nodemask));

Argh.... GFP_THISNODE must use the nid passed to alloc_pages_node and 
*not* the local numa node id. Only if the node specified to alloc_pages 
nodes is -1 will this work.

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