Commit a5d76b54 authored by KAMEZAWA Hiroyuki's avatar KAMEZAWA Hiroyuki Committed by Linus Torvalds

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: 's avatarYasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: 's avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: 's avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 75884fb1
......@@ -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++) \
......
#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
......@@ -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
};
......
......@@ -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
......
......@@ -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);
}
/*
* linux/mm/page_isolation.c
*/
#include <stddef.h>
#include <linux/mm.h>
#include <linux/page-isolation.h>
#include <linux/pageblock-flags.h>
#include "internal.h"
static inline struct page *
__first_valid_page(unsigned long pfn, unsigned long nr_pages)
{
int i;
for (i = 0; i < nr_pages; i++)
if (pfn_valid_within(pfn + i))
break;
if (unlikely(i == nr_pages))
return NULL;
return pfn_to_page(pfn + i);
}
/*
* start_isolate_page_range() -- make page-allocation-type of range of pages
* to be MIGRATE_ISOLATE.
* @start_pfn: The lower PFN of the range to be isolated.
* @end_pfn: The upper PFN of the range to be isolated.
*
* Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
* the range will never be allocated. Any free pages and pages freed in the
* future will not be allocated again.
*
* start_pfn/end_pfn must be aligned to pageblock_order.
* Returns 0 on success and -EBUSY if any part of range cannot be isolated.
*/
int
start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long pfn;
unsigned long undo_pfn;
struct page *page;
BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
for (pfn = start_pfn;
pfn < end_pfn;
pfn += pageblock_nr_pages) {
page = __first_valid_page(pfn, pageblock_nr_pages);
if (page && set_migratetype_isolate(page)) {
undo_pfn = pfn;
goto undo;
}
}
return 0;
undo:
for (pfn = start_pfn;
pfn <= undo_pfn;
pfn += pageblock_nr_pages)
unset_migratetype_isolate(pfn_to_page(pfn));
return -EBUSY;
}
/*
* Make isolated pages available again.
*/
int
undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long pfn;
struct page *page;
BUG_ON((start_pfn) & (pageblock_nr_pages - 1));
BUG_ON((end_pfn) & (pageblock_nr_pages - 1));
for (pfn = start_pfn;
pfn < end_pfn;
pfn += pageblock_nr_pages) {
page = __first_valid_page(pfn, pageblock_nr_pages);
if (!page || get_pageblock_flags(page) != MIGRATE_ISOLATE)
continue;
unset_migratetype_isolate(page);
}
return 0;
}
/*
* Test all pages in the range is free(means isolated) or not.
* all pages in [start_pfn...end_pfn) must be in the same zone.
* zone->lock must be held before call this.
*
* Returns 0 if all pages in the range is isolated.
*/
static int
__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn)
{
struct page *page;
while (pfn < end_pfn) {
if (!pfn_valid_within(pfn)) {
pfn++;
continue;
}
page = pfn_to_page(pfn);
if (PageBuddy(page))
pfn += 1 << page_order(page);
else if (page_count(page) == 0 &&
page_private(page) == MIGRATE_ISOLATE)
pfn += 1;
else
break;
}
if (pfn < end_pfn)
return 0;
return 1;
}
int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
{
unsigned long pfn;
struct page *page;
pfn = start_pfn;
/*
* Note: pageblock_nr_page != MAX_ORDER. Then, chunks of free page
* is not aligned to pageblock_nr_pages.
* Then we just check pagetype fist.
*/
for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
page = __first_valid_page(pfn, pageblock_nr_pages);
if (page && get_pageblock_flags(page) != MIGRATE_ISOLATE)
break;
}
if (pfn < end_pfn)
return -EBUSY;
/* Check all pages are free or Marked as ISOLATED */
if (__test_page_isolated_in_pageblock(start_pfn, end_pfn))
return 0;
return -EBUSY;
}
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