memory unplug: page offline

Logic.
 - set all pages in  [start,end)  as isolated migration-type.
   by this, all free pages in the range will be not-for-use.
 - Migrate all LRU pages in the range.
 - Test all pages in the range's refcnt is zero or not.

Todo:
 - allocate migration destination page from better area.
 - confirm page_count(page)== 0 && PageReserved(page) page is safe to be freed..
 (I don't like this kind of page but..
 - Find out pages which cannot be migrated.
 - more running tests.
 - Use reclaim for unplugging other memory type area.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 5 insertions, 1 deletions

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index d9725a28a265..5fdbc814c2eb 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -35,6 +35,7 @@ extern const char linux_proc_banner[];
 #define ALIGN(x,a)              __ALIGN_MASK(x,(typeof(x))(a)-1)
 #define __ALIGN_MASK(x,mask)    (((x)+(mask))&~(mask))
 #define PTR_ALIGN(p, a)         ((typeof(p))ALIGN((unsigned long)(p), (a)))
+#define IS_ALIGNED(x,a)         (((x) % ((typeof(x))(a))) == 0)
 
 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
 
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 0a14dad95453..665951ef0390 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -58,7 +58,10 @@ extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
 extern void online_page(struct page *page);
 /* VM interface that may be used by firmware interface */
 extern int online_pages(unsigned long, unsigned long);
-
+#ifdef CONFIG_MEMORY_HOTREMOVE
+extern int offline_pages(unsigned long, unsigned long, unsigned long);
+extern void __offline_isolated_pages(unsigned long, unsigned long);
+#endif
 /* reasonably generic interface to expand the physical pages in a zone  */
 extern int __add_pages(struct zone *zone, unsigned long start_pfn,
         unsigned long nr_pages);