From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wen Congyang <wency@cn.fujitsu.com>
Date: Mon, 30 Jul 2012 02:03:27 +0000
Subject: Re: [RFC PATCH v5 19/19] memory-hotplug: remove sysfs file of node
Message-Id: <5015EB6F.40901@cn.fujitsu.com>
List-Id: <linux-sh.vger.kernel.org>
References: <50126B83.3050201@cn.fujitsu.com> <50126F21.803@cn.fujitsu.com> <5012712E.9000005@jp.fujitsu.com>
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To: Yasuaki Ishimatsu <isimatu.yasuaki@jp.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

At 07/27/2012 06:45 PM, Yasuaki Ishimatsu Wrote:
> 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.

node_spanned_pages = present_pages + hole_pages

So present_pages is always less or equal than spanned_pages, and I think
checking present pages is better.

Thanks
Wen Congyang

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