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Commit a5d76b54 authored by KAMEZAWA Hiroyuki's avatar KAMEZAWA Hiroyuki Committed by Linus Torvalds
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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: default avatarYasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 75884fb1

include/linux/mmzone.h

+2 −1
Original line number Diff line number Diff line
@@ -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++) \

include/linux/page-isolation.h

0 → 100644
+37 −0
Original line number Diff line number Diff line 
#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

include/linux/pageblock-flags.h

+1 −1
Original line number Diff line number Diff line
@@ -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

};

mm/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -11,7 +11,7 @@ obj-y := bootmem.o filemap.o mempool.o oom_kill.o fadvise.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

mm/page_alloc.c

+44 −0
Original line number Diff line number Diff line
@@ -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>
@@ -4433,3 +4434,46 @@ void set_pageblock_flags_group(struct page *page, unsigned long flags, 
		else

			__clear_bit(bitidx + start_bitidx, bitmap);

}



/*

 * This is designed as sub function...plz see page_isolation.c also.

 * 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);

	/*

	 * In future, more migrate types will be able to be isolation target.

	 */

	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 unset_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);

}