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SubjectRe: [PATCH v4 3/13] memory-hotplug : check whether memory is present or not
Hi Wen,

2012/07/18 19:25, Wen Congyang wrote:
> At 07/18/2012 06:07 PM, Yasuaki Ishimatsu Wrote:
>> 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.
>>
>> 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>
>>
>> ---
>> include/linux/mmzone.h | 21 +++++++++++++++++++++
>> mm/memory_hotplug.c | 13 +++++++++++++
>> 2 files changed, 34 insertions(+)
>>
>> Index: linux-3.5-rc6/include/linux/mmzone.h
>> ===================================================================
>> --- linux-3.5-rc6.orig/include/linux/mmzone.h 2012-07-08 09:23:56.000000000 +0900
>> +++ linux-3.5-rc6/include/linux/mmzone.h 2012-07-17 16:10:21.588186145 +0900
>> @@ -1168,6 +1168,27 @@ 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 + 1))
>> + continue;
>> + else {
>> + unlock_memory_hotplug();
>
> Why do you unlock memory hotplug here? The caller will do it.

Ah, you are right. In this case, the function should only return -EINVAL.

Thansks,
Yasuaki Ishimatsu
>
> Thanks
> Wen Congyang
>
>> + 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
>> Index: linux-3.5-rc6/mm/memory_hotplug.c
>> ===================================================================
>> --- linux-3.5-rc6.orig/mm/memory_hotplug.c 2012-07-17 14:26:40.000000000 +0900
>> +++ linux-3.5-rc6/mm/memory_hotplug.c 2012-07-17 16:09:50.070580170 +0900
>> @@ -467,6 +467,19 @@ int __ref online_pages(unsigned long pfn
>> 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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