From mboxrd@z Thu Jan  1 00:00:00 1970
From: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Date: Fri, 27 Jul 2012 10:45:02 +0000
Subject: Re: [RFC PATCH v5 19/19] memory-hotplug: remove sysfs file of node
Message-Id: <5012712E.9000005@jp.fujitsu.com>
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References: <50126B83.3050201@cn.fujitsu.com> <50126F21.803@cn.fujitsu.com>
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To: Wen Congyang <wency@cn.fujitsu.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-ia64@vger.kernel.org, cmetcalf@tilera.com, rientjes@google.com, liuj97@gmail.com, len.brown@intel.com, benh@kernel.crashing.org, paulus@samba.org, cl@linux.com, minchan.kim@gmail.com, akpm@linux-foundation.org, kosaki.motohiro@jp.fujitsu.com

Hi Wen,

2012/07/27 19:36, Wen Congyang wrote:
> From: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>
> The patch adds node_set_offline() and unregister_one_node() to remove_memory()
> for removing sysfs file of node.
>
> CC: David Rientjes <rientjes@google.com>
> CC: Jiang Liu <liuj97@gmail.com>
> CC: Len Brown <len.brown@intel.com>
> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> CC: Paul Mackerras <paulus@samba.org>
> CC: Christoph Lameter <cl@linux.com>
> Cc: Minchan Kim <minchan.kim@gmail.com>
> CC: Andrew Morton <akpm@linux-foundation.org>
> CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> CC: Wen Congyang <wency@cn.fujitsu.com>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
> ---
>   mm/memory_hotplug.c |    5 +++++
>   1 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 5ac035f..5681968 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1267,6 +1267,11 @@ int __ref remove_memory(int nid, u64 start, u64 size)
>   	/* remove memmap entry */
>   	firmware_map_remove(start, start + size, "System RAM");
>
> +	if (!node_present_pages(nid)) {

Applying [PATCH v5 17/19], pgdat->node_spanned_pages can become 0 when
all memory of the pgdat is removed. When pgdat->node_spanned_pages is 0,
it means the pgdat has no memory. So I think node_spanned_pages() is
better.

Thanks,
Yasuaki Ishimatsu

> +		node_set_offline(nid);
> +		unregister_one_node(nid);
> +	}
> +
>   	arch_remove_memory(start, size);
>   out:
>   	unlock_memory_hotplug();
>