[RFC,v5,05/19] memory-hotplug: check whether memory is present or not

Commit Message

Wen Congyang July 27, 2012, 10:28 a.m. UTC

From: Yasuaki Ishimatsu <[e-mail]>

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 <[e-mail]>
CC: Jiang Liu <[e-mail]>
CC: Len Brown <[e-mail]>
CC: Benjamin Herrenschmidt <[e-mail]>
CC: Paul Mackerras <[e-mail]>
CC: Christoph Lameter <[e-mail]>
Cc: Minchan Kim <[e-mail]>
CC: Andrew Morton <[e-mail]>
CC: KOSAKI Motohiro <[e-mail]>
CC: Wen Congyang <[e-mail]>
Signed-off-by: Yasuaki Ishimatsu <[e-mail]>
---
 include/linux/mmzone.h |   19 +++++++++++++++++++
 mm/memory_hotplug.c    |   13 +++++++++++++
 2 files changed, 32 insertions(+), 0 deletions(-)

Comments

Tony Luck July 27, 2012, 8:17 p.m. UTC | #1

On Fri, Jul 27, 2012 at 3:28 AM, Wen Congyang <[e-mail]> wrote:
> +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))

Typo? I think you meant "pfn + i"

> +                       continue;
> +               else
> +                       return -EINVAL;
> +       }
> +       return 0;
> +}

-Tony
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Wen Congyang July 30, 2012, 1:57 a.m. UTC | #2

At 07/28/2012 04:17 AM, Tony Luck Wrote:
> On Fri, Jul 27, 2012 at 3:28 AM, Wen Congyang <[e-mail]> wrote:
>> +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))
> 
> Typo? I think you meant "pfn + i"

Typo error.

Thanks for pointing it out.
Wen Congyang

> 
>> +                       continue;
>> +               else
>> +                       return -EINVAL;
>> +       }
>> +       return 0;
>> +}
> 
> -Tony
> 

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Patch

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 458988b..822f705 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1168,6 +1168,25 @@  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 + 1))
+			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 5af0a9f..d510be0 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;