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

From: Wen Congyang
Date: Sun Jul 29 2012 - 21:58:33 EST


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@xxxxxxxxxxxxxx>
>>
>> The patch adds node_set_offline() and unregister_one_node() to
>> remove_memory()
>> for removing sysfs file of node.
>>
>> CC: David Rientjes <rientjes@xxxxxxxxxx>
>> CC: Jiang Liu <liuj97@xxxxxxxxx>
>> CC: Len Brown <len.brown@xxxxxxxxx>
>> CC: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
>> CC: Paul Mackerras <paulus@xxxxxxxxx>
>> CC: Christoph Lameter <cl@xxxxxxxxx>
>> Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
>> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> CC: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
>> CC: Wen Congyang <wency@xxxxxxxxxxxxxx>
>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
>> ---
>> 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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