linux-kernel - Re: [RFC PATCH v5 19/19] memory-hotplug: remove sysfs file of node

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Message-ID: <5015EB6F.40901@cn.fujitsu.com>
Date:	Mon, 30 Jul 2012 10:03:27 +0800
From:	Wen Congyang <wency@...fujitsu.com>
To:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
CC:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, linux-acpi@...r.kernel.org,
	linux-s390@...r.kernel.org, linux-sh@...r.kernel.org,
	linux-ia64@...r.kernel.org, cmetcalf@...era.com,
	rientjes@...gle.com, liuj97@...il.com, len.brown@...el.com,
	benh@...nel.crashing.org, paulus@...ba.org, cl@...ux.com,
	minchan.kim@...il.com, akpm@...ux-foundation.org,
	kosaki.motohiro@...fujitsu.com
Subject: Re: [RFC PATCH v5 19/19] memory-hotplug: remove sysfs file of node

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@...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@...gle.com>
>> CC: Jiang Liu <liuj97@...il.com>
>> CC: Len Brown <len.brown@...el.com>
>> CC: Benjamin Herrenschmidt <benh@...nel.crashing.org>
>> CC: Paul Mackerras <paulus@...ba.org>
>> CC: Christoph Lameter <cl@...ux.com>
>> Cc: Minchan Kim <minchan.kim@...il.com>
>> CC: Andrew Morton <akpm@...ux-foundation.org>
>> CC: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
>> CC: Wen Congyang <wency@...fujitsu.com>
>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@...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();
>>
> 
> 
> 

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