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Subject: Re: [RFC:Patch: 008/008](memory hotplug) remove_pgdat() function
From: Peter Zijlstra <peterz@infradead.org>
To: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>,
       Andrew Morton <akpm@linux-foundation.org>, Mel Gorman <mel@csn.ul.ie>,
       Christoph Lameter <cl@linux-foundation.org>,
       linux-mm <linux-mm@kvack.org>,
       Linux Kernel ML <linux-kernel@vger.kernel.org>
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Date: Sat, 06 Sep 2008 16:21:35 +0200
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On Thu, 2008-07-31 at 21:04 +0900, Yasunori Goto wrote:

> +int remove_pgdat(int nid)
> +{
> +	struct pglist_data *pgdat = NODE_DATA(nid);
> +
> +	if (cpus_busy_on_node(nid))
> +		return -EBUSY;
> +
> +	if (sections_busy_on_node(pgdat))
> +		return -EBUSY;
> +
> +	node_set_offline(nid);
> +	synchronize_sched();
> +	synchronize_srcu(&pgdat_remove_srcu);
> +
> +	free_pgdat(nid, pgdat);
> +
> +	return 0;
> +}

FWIW synchronize_sched() is the wrong function to use here,
synchronize_rcu() is the right one.