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Date: Mon, 14 Feb 2011 12:25:40 +0100
From: Tejun Heo <tj@kernel.org>
To: Yinghai Lu <yinghai@kernel.org>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org, brgerst@gmail.com,
        gorcunov@gmail.com, shaohui.zheng@intel.com, rientjes@google.com,
        mingo@elte.hu, hpa@linux.intel.com
Subject: Re: [PATCH 02/26] x86-64, NUMA: Simplify hotplug node handling in
 acpi_numa_memory_affinity_init()
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Hello, Yinghai.

On Sat, Feb 12, 2011 at 10:13:51AM -0800, Yinghai Lu wrote:
> > Eh?  The oldnode thing will restore the node to initial state thus
> > fulfilling the node empty condition.  Am I missing something?
> > 
> 
> yes. nd get restored, but it keep node_parsed set for that kind of node.

So, this is the code snippet.  Both @nd->start and end are zero and
nodes_parsed for @node is clear.

	nd = &nodes[node];
	oldnode = *nd;

@oldnode->start, end == 0.

	if (!node_test_and_set(node, nodes_parsed)) {
		nd->start = start;
		nd->end = end;
This path is taken and @nd->start and end are set.
	} else {
		if (start < nd->start)
			nd->start = start;
		if (nd->end < end)
			nd->end = end;
	}

	printk(KERN_INFO "SRAT: Node %u PXM %u %lx-%lx\n", node, pxm,
	       start, end);

	if (ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE) {
		update_nodes_add(node, start, end);
		/* restore nodes[node] */
		*nd = oldnode;
@nd->start and end are restored to zero.
		if ((nd->start | nd->end) == 0)
			node_clear(node, nodes_parsed);
and @nodes_parsed is cleared.
	}

So, what the hell am I missing?

-- 
tejun