Hi, ishimatsu
At 09/05/2012 05:25 PM, we...@cn.fujitsu.com Wrote:
> From: Yasuaki Ishimatsu <isimatu.yasu...@jp.fujitsu.com>
>
> 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?
Thanks
Wen Congyang
>
> CC: David Rientjes <rient...@google.com>
> CC: Jiang Liu <liu...@gmail.com>
> CC: Len Brown <len.br...@intel.com>
> CC: Benjamin Herrenschmidt <b...@kernel.crashing.org>
> CC: Paul Mackerras <pau...@samba.org>
> CC: Christoph Lameter <c...@linux.com>
> Cc: Minchan Kim <minchan....@gmail.com>
> CC: Andrew Morton <a...@linux-foundation.org>
> CC: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com>
> CC: Wen Congyang <we...@cn.fujitsu.com>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasu...@jp.fujitsu.com>
> ---
> 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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