At 09/11/2012 10:24 AM, Yasuaki Ishimatsu Wrote:
> Hi Wen,
>
> 2012/09/11 11:15, Wen Congyang wrote:
>> Hi, ishimatsu
>>
>> At 09/05/2012 05:25 PM, wency@xxxxxxxxxxxxxx Wrote:
>>> From: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
>>>
>>> If system supports memory hot-remove, online_pages() may online
>>> removed pages.
>>> So online_pages() need to check whether onlining pages are present or
>>> not.
>>
>> Because we use memory_block_change_state() to hotremoving memory, I think
>> this patch can be removed. What do you think?
>
> Pleae teach me detals a little more. If we use memory_block_change_state(),
> does the conflict never occur? Why?
I misunderstand sth, please ignore it.
Wen Congyang
>
> Thansk,
> Yasuaki Ishimatsu
>
>> Thanks
>> Wen Congyang
>>
>>>
>>> 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>
>>> ---
>>> include/linux/mmzone.h | 19 +++++++++++++++++++
>>> mm/memory_hotplug.c | 13 +++++++++++++
>>> 2 files changed, 32 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
>>> index 2daa54f..ac3ae30 100644
>>> --- a/include/linux/mmzone.h
>>> +++ b/include/linux/mmzone.h
>>> @@ -1180,6 +1180,25 @@ void sparse_init(void);
>>> #define sparse_index_init(_sec, _nid) do {} while (0)
>>> #endif /* CONFIG_SPARSEMEM */
>>>
>>> +#ifdef CONFIG_SPARSEMEM
>>> +static inline int pfns_present(unsigned long pfn, unsigned long
>>> nr_pages)
>>> +{
>>> + int i;
>>> + for (i = 0; i < nr_pages; i++) {
>>> + if (pfn_present(pfn + i))
>>> + continue;
>>> + else
>>> + return -EINVAL;
>>> + }
>>> + return 0;
>>> +}
>>> +#else
>>> +static inline int pfns_present(unsigned long pfn, unsigned long
>>> nr_pages)
>>> +{
>>> + return 0;
>>> +}
>>> +#endif /* CONFIG_SPARSEMEM*/
>>> +
>>> #ifdef CONFIG_NODES_SPAN_OTHER_NODES
>>> bool early_pfn_in_nid(unsigned long pfn, int nid);
>>> #else
>>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
>>> index 49f7747..299747d 100644
>>> --- a/mm/memory_hotplug.c
>>> +++ b/mm/memory_hotplug.c
>>> @@ -467,6 +467,19 @@ int __ref online_pages(unsigned long pfn,
>>> unsigned long nr_pages)
>>> struct memory_notify arg;
>>>
>>> lock_memory_hotplug();
>>> + /*
>>> + * If system supports memory hot-remove, the memory may have been
>>> + * removed. So we check whether the memory has been removed or not.
>>> + *
>>> + * Note: When CONFIG_SPARSEMEM is defined, pfns_present() become
>>> + * effective. If CONFIG_SPARSEMEM is not defined,
>>> pfns_present()
>>> + * always returns 0.
>>> + */
>>> + ret = pfns_present(pfn, nr_pages);
>>> + if (ret) {
>>> + unlock_memory_hotplug();
>>> + return ret;
>>> + }
>>> arg.start_pfn = pfn;
>>> arg.nr_pages = nr_pages;
>>> arg.status_change_nid = -1;
>>
>
>
>
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