memory unplug v4 intro [4/6] page isolation

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

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.

If make_pagetype_isolated(start,end) is called,
 - migratetype of the range turns to be MIGRATE_ISOLATE  if 
   its current type is MIGRATE_MOVABLE or MIGRATE_RESERVE.
 - MIGRATE_ISOLATE is not on migratetype fallback list.

Then, pages of this migratetype will not be allocated even if it is free.

Now, this patch only can treat the range aligned to MAX_ORDER.
This will be fixed if Mel's new work is merged.

Changes V3 -> V4
 - removed MIGRATE_ISOLATE check in free_hot_cold_page().
 - test_and_next_pages_isolated() is added, which sees Buddy information.
 - rounddown() macro is added to kernel.h, my own macro is removed.
 - is_page_isolated() function is removed.
 - change function names to be clearer.
   make_pagetype_isolated()/make_pagetype_movable().

Signed-Off-By: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-Off-By: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

---
 include/linux/kernel.h          |    1 
 include/linux/mmzone.h          |    3 +
 include/linux/page-isolation.h  |   47 ++++++++++++++++++++++++++++
 include/linux/pageblock-flags.h |    2 -
 mm/Makefile                     |    2 -
 mm/page_alloc.c                 |   63 +++++++++++++++++++++++++++++++++++++
 mm/page_isolation.c             |   67 ++++++++++++++++++++++++++++++++++++++++
 7 files changed, 182 insertions(+), 3 deletions(-)

Index: devel-2.6.22-rc4-mm2/include/linux/mmzone.h
===================================================================
--- devel-2.6.22-rc4-mm2.orig/include/linux/mmzone.h
+++ devel-2.6.22-rc4-mm2/include/linux/mmzone.h
@@ -39,7 +39,8 @@ extern int page_group_by_mobility_disabl
 #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++) \
Index: devel-2.6.22-rc4-mm2/include/linux/pageblock-flags.h
===================================================================
--- devel-2.6.22-rc4-mm2.orig/include/linux/pageblock-flags.h
+++ devel-2.6.22-rc4-mm2/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
 };
 
Index: devel-2.6.22-rc4-mm2/mm/page_alloc.c
===================================================================
--- devel-2.6.22-rc4-mm2.orig/mm/page_alloc.c
+++ devel-2.6.22-rc4-mm2/mm/page_alloc.c
@@ -41,6 +41,7 @@
 #include <linux/pfn.h>
 #include <linux/backing-dev.h>
 #include <linux/fault-inject.h>
+#include <linux/page-isolation.h>
 
 #include <asm/tlbflush.h>
 #include <asm/div64.h>
@@ -4409,3 +4410,65 @@ void set_pageblock_flags_group(struct pa
 		else
 			__clear_bit(bitidx + start_bitidx, bitmap);
 }
+
+/*
+ * Chack a range of pages are isolated or not.
+ * returns next pfn to be tested.
+ * If pfn is not isoalted, returns 0.
+ */
+
+unsigned long test_and_next_isolated_page(unsigned long pfn)
+{
+	struct page *page;
+	if (!pfn_valid(pfn))
+		return 0;
+	page = pfn_to_page(pfn);
+	if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
+		return 0;
+	if (PageBuddy(page))
+		return pfn + (1 << page_order(page));
+	/* Means pages in pcp list */
+	if (page_count(page) == 0 && page_private(page) == MIGRATE_ISOLATE)
+		return pfn + 1;
+	return 0;
+}
+
+/*
+ * set/clear page block's type to be ISOLATE.
+ * page allocater never alloc memory from ISOLATE block.
+ */
+
+
+int set_migratetype_isolate(struct page *page)
+{
+	struct zone *zone;
+	unsigned long flags;
+	int ret = -EBUSY;
+
+	zone = page_zone(page);
+	spin_lock_irqsave(&zone->lock, flags);
+	if (get_pageblock_migratetype(page) != MIGRATE_MOVABLE)
+		goto out;
+	set_pageblock_migratetype(page, MIGRATE_ISOLATE);
+	move_freepages_block(zone, page, MIGRATE_ISOLATE);
+	ret = 0;
+out:
+	spin_unlock_irqrestore(&zone->lock, flags);
+	if (!ret)
+		drain_all_local_pages();
+	return ret;
+}
+
+void clear_migratetype_isolate(struct page *page)
+{
+	struct zone *zone;
+	unsigned long flags;
+	zone = page_zone(page);
+	spin_lock_irqsave(&zone->lock, flags);
+	if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
+		goto out;
+	set_pageblock_migratetype(page, MIGRATE_MOVABLE);
+	move_freepages_block(zone, page, MIGRATE_MOVABLE);
+out:
+	spin_unlock_irqrestore(&zone->lock, flags);
+}
Index: devel-2.6.22-rc4-mm2/mm/page_isolation.c
===================================================================
--- /dev/null
+++ devel-2.6.22-rc4-mm2/mm/page_isolation.c
@@ -0,0 +1,67 @@
+/*
+ * linux/mm/page_isolation.c
+ */
+
+#include <stddef.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/page-isolation.h>
+
+int
+make_pagetype_isolated(unsigned long start_pfn, unsigned long end_pfn)
+{
+	unsigned long pfn, start_pfn_aligned, end_pfn_aligned;
+	unsigned long undo_pfn;
+
+	start_pfn_aligned = rounddown(start_pfn, NR_PAGES_ISOLATION_BLOCK);
+	end_pfn_aligned = roundup(end_pfn, NR_PAGES_ISOLATION_BLOCK);
+
+	for (pfn = start_pfn_aligned;
+	     pfn < end_pfn_aligned;
+	     pfn += NR_PAGES_ISOLATION_BLOCK)
+		if (set_migratetype_isolate(pfn_to_page(pfn))) {
+			undo_pfn = pfn;
+			goto undo;
+		}
+	return 0;
+undo:
+	for (pfn = start_pfn_aligned;
+	     pfn <= undo_pfn;
+	     pfn += NR_PAGES_ISOLATION_BLOCK)
+		clear_migratetype_isolate(pfn_to_page(pfn));
+
+	return -EBUSY;
+}
+
+
+int
+make_pagetype_movable(unsigned long start_pfn, unsigned long end_pfn)
+{
+	unsigned long pfn, start_pfn_aligned, end_pfn_aligned;
+	start_pfn_aligned = rounddown(start_pfn, NR_PAGES_ISOLATION_BLOCK);
+        end_pfn_aligned = roundup(end_pfn, NR_PAGES_ISOLATION_BLOCK);
+
+	for (pfn = start_pfn_aligned;
+	     pfn < end_pfn_aligned;
+	     pfn += NR_PAGES_ISOLATION_BLOCK)
+		clear_migratetype_isolate(pfn_to_page(pfn));
+	return 0;
+}
+
+int
+test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
+{
+	unsigned long pfn;
+
+	pfn = start_pfn;
+	while (pfn < end_pfn) {
+		if (!pfn_valid(pfn)) {
+			pfn++;
+			continue;
+		}
+		pfn = test_and_next_isolated_page(pfn);
+		if (!pfn)
+			break;
+	}
+	return (pfn < end_pfn)? -EBUSY : 0;
+}
Index: devel-2.6.22-rc4-mm2/include/linux/page-isolation.h
===================================================================
--- /dev/null
+++ devel-2.6.22-rc4-mm2/include/linux/page-isolation.h
@@ -0,0 +1,47 @@
+#ifndef __LINUX_PAGEISOLATION_H
+#define __LINUX_PAGEISOLATION_H
+/*
+ * Define an interface for capturing and isolating some amount of
+ * contiguous pages.
+ * isolated pages are freed but wll never be allocated until they are
+ * pushed back.
+ *
+ * This isolation function requires some alignment.
+ */
+
+#define PAGE_ISOLATION_ORDER	(MAX_ORDER - 1)
+#define NR_PAGES_ISOLATION_BLOCK	(1 << PAGE_ISOLATION_ORDER)
+
+/*
+ * set page isolation range.
+ * If specified range includes migrate types other than MOVABLE,
+ * this will fail with -EBUSY.
+ */
+extern int
+make_pagetype_isolated(unsigned long start_pfn, unsigned long end_pfn);
+
+/*
+ *  Changes MIGRATE_ISOLATE to MIGRATE_MOVABLE.
+ */
+extern int
+make_pagetype_movable(unsigned long start_pfn, unsigned long end_pfn);
+
+/*
+ * test all pages are isolated or not.
+ */
+extern int
+test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn);
+
+/* helper test routine for check page is isolated or not */
+extern unsigned long
+test_and_next_isolated_page(unsigned long 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 clear_migratetype_isolate(struct page *page);
+
+
+#endif
Index: devel-2.6.22-rc4-mm2/mm/Makefile
===================================================================
--- devel-2.6.22-rc4-mm2.orig/mm/Makefile
+++ devel-2.6.22-rc4-mm2/mm/Makefile
@@ -11,7 +11,7 @@ obj-y			:= bootmem.o filemap.o mempool.o
 			   page_alloc.o page-writeback.o pdflush.o \
 			   readahead.o swap.o truncate.o vmscan.o \
 			   prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \
-			   $(mmu-y)
+			   page_isolation.o $(mmu-y)
 
 obj-$(CONFIG_BOUNCE)	+= bounce.o
 obj-$(CONFIG_SWAP)	+= page_io.o swap_state.o swapfile.o thrash.o
Index: devel-2.6.22-rc4-mm2/include/linux/kernel.h
===================================================================
--- devel-2.6.22-rc4-mm2.orig/include/linux/kernel.h
+++ devel-2.6.22-rc4-mm2/include/linux/kernel.h
@@ -40,6 +40,7 @@ extern const char linux_proc_banner[];
 #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f))
 #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))
 #define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y))
+#define rounddown(x, y) ((x)/(y)) * (y)
 
 /**
  * upper_32_bits - return bits 32-63 of a number

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>