Re: [PATCH for 2.6.16] Handle holes in node mask in node fallback list initialization

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

Andi Kleen wrote:
> On Friday 17 February 2006 02:40, Christoph Lameter wrote:
>> What happens if another node beyond higest_node comes online later?
>> Or one node in between comes online?
> 
> I don't know. Whoever implements node hotplug has to handle it.
> But I'm pretty sure the old code also didn't handle it, so it's not
> a regression.
> 
> My primary interest is just to get all these Opterons booting again.
> 

All existing pgdat's default zonelist should be refreshed when a new
node comes in. So,I think this patch wouldn't be problem.
It's node-hotplug's problem.


Goto is implementing it now by this:
==
+static int __build_all_zonelists(void *dummy)
+{
+	int i;
+	for_each_online_node(i)
+		build_zonelists(NODE_DATA(i));
+	/* XXX: Cpuset must be updated when node is hotplugged. */
+	return 0;
+}
<snip>
+	stop_machine_run(__build_all_zonelists, zone->zone_pgdat, NR_CPUS);
==

If this is ok, next problem is "how to remove pgdat/zone from all zonelist....".

If there are no performance problem, adding list and seqlock , callback to
zonelist is one way to manage add-remove-zone/pgdat to zonelist.
But this will make codes more complicated.

Thanks,

-- Kame


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