memory unplug: page isolation
Implement generic chunk-of-pages isolation method by using page grouping ops.
This patch add MIGRATE_ISOLATE to MIGRATE_TYPES. By this
- MIGRATE_TYPES increases.
- bitmap for migratetype is enlarged.
pages of MIGRATE_ISOLATE migratetype will not be allocated even if it is free.
By this, you can isolated *freed* pages from users. How-to-free pages is not
a purpose of this patch. You may use reclaim and migrate codes to free pages.
If start_isolate_page_range(start,end) is called,
- migratetype of the range turns to be MIGRATE_ISOLATE if
its type is MIGRATE_MOVABLE. (*) this check can be updated if other
memory reclaiming works make progress.
- MIGRATE_ISOLATE is not on migratetype fallback list.
- All free pages and will-be-freed pages are isolated.
To check all pages in the range are isolated or not, use test_pages_isolated(),
To cancel isolation, use undo_isolate_page_range().
Changes V6 -> V7
- removed unnecessary #ifdef
There are HOLES_IN_ZONE handling codes...I'm glad if we can remove them..
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 20ea42c..f4bfe82 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -37,7 +37,8 @@
#define MIGRATE_RECLAIMABLE 1
#define MIGRATE_MOVABLE 2
#define MIGRATE_RESERVE 3
-#define MIGRATE_TYPES 4
+#define MIGRATE_ISOLATE 4 /* can't allocate from here */
+#define MIGRATE_TYPES 5
#define for_each_migratetype_order(order, type) \
for (order = 0; order < MAX_ORDER; order++) \
diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
new file mode 100644
index 0000000..051c1b1
--- /dev/null
+++ b/include/linux/page-isolation.h
@@ -0,0 +1,37 @@
+#ifndef __LINUX_PAGEISOLATION_H
+#define __LINUX_PAGEISOLATION_H
+
+/*
+ * Changes migrate type in [start_pfn, end_pfn) to be MIGRATE_ISOLATE.
+ * If specified range includes migrate types other than MOVABLE,
+ * this will fail with -EBUSY.
+ *
+ * For isolating all pages in the range finally, the caller have to
+ * free all pages in the range. test_page_isolated() can be used for
+ * test it.
+ */
+extern int
+start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn);
+
+/*
+ * Changes MIGRATE_ISOLATE to MIGRATE_MOVABLE.
+ * target range is [start_pfn, end_pfn)
+ */
+extern int
+undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn);
+
+/*
+ * test all pages in [start_pfn, end_pfn)are isolated or not.
+ */
+extern int
+test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn);
+
+/*
+ * Internal funcs.Changes pageblock's migrate type.
+ * Please use make_pagetype_isolated()/make_pagetype_movable().
+ */
+extern int set_migratetype_isolate(struct page *page);
+extern void unset_migratetype_isolate(struct page *page);
+
+
+#endif
diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h
index 9ea1308..e875905 100644
--- a/include/linux/pageblock-flags.h
+++ b/include/linux/pageblock-flags.h
@@ -31,7 +31,7 @@
/* Bit indices that affect a whole block of pages */
enum pageblock_bits {
- PB_range(PB_migrate, 2), /* 2 bits required for migrate types */
+ PB_range(PB_migrate, 3), /* 3 bits required for migrate types */
NR_PAGEBLOCK_BITS
};