[linux-2.6-block.git] / mm / swap.c

/*
 *  linux/mm/swap.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

/*
 * This file contains the default values for the opereation of the
 * Linux VM subsystem. Fine-tuning documentation can be found in
 * Documentation/sysctl/vm.txt.
 * Started 18.12.91
 * Swap aging added 23.2.95, Stephen Tweedie.
 * Buffermem limits added 12.3.98, Rik van Riel.
 */

#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/kernel_stat.h>
#include <linux/swap.h>
#include <linux/mman.h>
#include <linux/pagemap.h>
#include <linux/pagevec.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm_inline.h>
#include <linux/buffer_head.h>	/* for try_to_release_page() */
#include <linux/module.h>
#include <linux/percpu_counter.h>
#include <linux/percpu.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <linux/init.h>

/* How many pages do we try to swap or page in/out together? */
int page_cluster;

static void put_compound_page(struct page *page)
{
	page = (struct page *)page_private(page);
	if (put_page_testzero(page)) {
		void (*dtor)(struct page *page);

		dtor = (void (*)(struct page *))page[1].lru.next;
		(*dtor)(page);
	}
}

void put_page(struct page *page)
{
	if (unlikely(PageCompound(page)))
		put_compound_page(page);
	else if (put_page_testzero(page))
		__page_cache_release(page);
}
EXPORT_SYMBOL(put_page);

/**
 * put_pages_list(): release a list of pages
 *
 * Release a list of pages which are strung together on page.lru.  Currently
 * used by read_cache_pages() and related error recovery code.
 *
 * @pages: list of pages threaded on page->lru
 */
void put_pages_list(struct list_head *pages)
{
	while (!list_empty(pages)) {
		struct page *victim;

		victim = list_entry(pages->prev, struct page, lru);
		list_del(&victim->lru);
		page_cache_release(victim);
	}
}
EXPORT_SYMBOL(put_pages_list);

/*
 * Writeback is about to end against a page which has been marked for immediate
 * reclaim.  If it still appears to be reclaimable, move it to the tail of the
 * inactive list.  The page still has PageWriteback set, which will pin it.
 *
 * We don't expect many pages to come through here, so don't bother batching
 * things up.
 *
 * To avoid placing the page at the tail of the LRU while PG_writeback is still
 * set, this function will clear PG_writeback before performing the page
 * motion.  Do that inside the lru lock because once PG_writeback is cleared
 * we may not touch the page.
 *
 * Returns zero if it cleared PG_writeback.
 */
int rotate_reclaimable_page(struct page *page)
{
	struct zone *zone;
	unsigned long flags;

	if (PageLocked(page))
		return 1;
	if (PageDirty(page))
		return 1;
	if (PageActive(page))
		return 1;
	if (!PageLRU(page))
		return 1;

	zone = page_zone(page);
	spin_lock_irqsave(&zone->lru_lock, flags);
	if (PageLRU(page) && !PageActive(page)) {
		list_move_tail(&page->lru, &zone->inactive_list);
		__count_vm_event(PGROTATED);
	}
	if (!test_clear_page_writeback(page))
		BUG();
	spin_unlock_irqrestore(&zone->lru_lock, flags);
	return 0;
}

/*
 * FIXME: speed this up?
 */
void fastcall activate_page(struct page *page)
{
	struct zone *zone = page_zone(page);

	spin_lock_irq(&zone->lru_lock);
	if (PageLRU(page) && !PageActive(page)) {
		del_page_from_inactive_list(zone, page);
		SetPageActive(page);
		add_page_to_active_list(zone, page);
		__count_vm_event(PGACTIVATE);
	}
	spin_unlock_irq(&zone->lru_lock);
}

/*
 * Mark a page as having seen activity.
 *
 * inactive,unreferenced	->	inactive,referenced
 * inactive,referenced		->	active,unreferenced
 * active,unreferenced		->	active,referenced
 */
void fastcall mark_page_accessed(struct page *page)
{
	if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
		activate_page(page);
		ClearPageReferenced(page);
	} else if (!PageReferenced(page)) {
		SetPageReferenced(page);
	}
}

EXPORT_SYMBOL(mark_page_accessed);

/**
 * lru_cache_add: add a page to the page lists
 * @page: the page to add
 */
static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };

void fastcall lru_cache_add(struct page *page)
{
	struct pagevec *pvec = &get_cpu_var(lru_add_pvecs);

	page_cache_get(page);
	if (!pagevec_add(pvec, page))
		__pagevec_lru_add(pvec);
	put_cpu_var(lru_add_pvecs);
}

void fastcall lru_cache_add_active(struct page *page)
{
	struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs);

	page_cache_get(page);
	if (!pagevec_add(pvec, page))
		__pagevec_lru_add_active(pvec);
	put_cpu_var(lru_add_active_pvecs);
}

static void __lru_add_drain(int cpu)
{
	struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu);

	/* CPU is dead, so no locking needed. */
	if (pagevec_count(pvec))
		__pagevec_lru_add(pvec);
	pvec = &per_cpu(lru_add_active_pvecs, cpu);
	if (pagevec_count(pvec))
		__pagevec_lru_add_active(pvec);
}

void lru_add_drain(void)
{
	__lru_add_drain(get_cpu());
	put_cpu();
}

#ifdef CONFIG_NUMA
static void lru_add_drain_per_cpu(void *dummy)
{
	lru_add_drain();
}

/*
 * Returns 0 for success
 */
int lru_add_drain_all(void)
{
	return schedule_on_each_cpu(lru_add_drain_per_cpu, NULL);
}

#else

/*
 * Returns 0 for success
 */
int lru_add_drain_all(void)
{
	lru_add_drain();
	return 0;
}
#endif

/*
 * This path almost never happens for VM activity - pages are normally
 * freed via pagevecs.  But it gets used by networking.
 */
void fastcall __page_cache_release(struct page *page)
{
	if (PageLRU(page)) {
		unsigned long flags;
		struct zone *zone = page_zone(page);

		spin_lock_irqsave(&zone->lru_lock, flags);
		BUG_ON(!PageLRU(page));
		__ClearPageLRU(page);
		del_page_from_lru(zone, page);
		spin_unlock_irqrestore(&zone->lru_lock, flags);
	}
	free_hot_page(page);
}
EXPORT_SYMBOL(__page_cache_release);

/*
 * Batched page_cache_release().  Decrement the reference count on all the
 * passed pages.  If it fell to zero then remove the page from the LRU and
 * free it.
 *
 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
 * for the remainder of the operation.
 *
 * The locking in this function is against shrink_cache(): we recheck the
 * page count inside the lock to see whether shrink_cache grabbed the page
 * via the LRU.  If it did, give up: shrink_cache will free it.
 */
void release_pages(struct page **pages, int nr, int cold)
{
	int i;
	struct pagevec pages_to_free;
	struct zone *zone = NULL;

	pagevec_init(&pages_to_free, cold);
	for (i = 0; i < nr; i++) {
		struct page *page = pages[i];

		if (unlikely(PageCompound(page))) {
			if (zone) {
				spin_unlock_irq(&zone->lru_lock);
				zone = NULL;
			}
			put_compound_page(page);
			continue;
		}

		if (!put_page_testzero(page))
			continue;

		if (PageLRU(page)) {
			struct zone *pagezone = page_zone(page);
			if (pagezone != zone) {
				if (zone)
					spin_unlock_irq(&zone->lru_lock);
				zone = pagezone;
				spin_lock_irq(&zone->lru_lock);
			}
			BUG_ON(!PageLRU(page));
			__ClearPageLRU(page);
			del_page_from_lru(zone, page);
		}

		if (!pagevec_add(&pages_to_free, page)) {
			if (zone) {
				spin_unlock_irq(&zone->lru_lock);
				zone = NULL;
			}
			__pagevec_free(&pages_to_free);
			pagevec_reinit(&pages_to_free);
  		}
	}
	if (zone)
		spin_unlock_irq(&zone->lru_lock);

	pagevec_free(&pages_to_free);
}

/*
 * The pages which we're about to release may be in the deferred lru-addition
 * queues.  That would prevent them from really being freed right now.  That's
 * OK from a correctness point of view but is inefficient - those pages may be
 * cache-warm and we want to give them back to the page allocator ASAP.
 *
 * So __pagevec_release() will drain those queues here.  __pagevec_lru_add()
 * and __pagevec_lru_add_active() call release_pages() directly to avoid
 * mutual recursion.
 */
void __pagevec_release(struct pagevec *pvec)
{
	lru_add_drain();
	release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
	pagevec_reinit(pvec);
}

EXPORT_SYMBOL(__pagevec_release);

/*
 * pagevec_release() for pages which are known to not be on the LRU
 *
 * This function reinitialises the caller's pagevec.
 */
void __pagevec_release_nonlru(struct pagevec *pvec)
{
	int i;
	struct pagevec pages_to_free;

	pagevec_init(&pages_to_free, pvec->cold);
	for (i = 0; i < pagevec_count(pvec); i++) {
		struct page *page = pvec->pages[i];

		BUG_ON(PageLRU(page));
		if (put_page_testzero(page))
			pagevec_add(&pages_to_free, page);
	}
	pagevec_free(&pages_to_free);
	pagevec_reinit(pvec);
}

/*
 * Add the passed pages to the LRU, then drop the caller's refcount
 * on them.  Reinitialises the caller's pagevec.
 */
void __pagevec_lru_add(struct pagevec *pvec)
{
	int i;
	struct zone *zone = NULL;

	for (i = 0; i < pagevec_count(pvec); i++) {
		struct page *page = pvec->pages[i];
		struct zone *pagezone = page_zone(page);

		if (pagezone != zone) {
			if (zone)
				spin_unlock_irq(&zone->lru_lock);
			zone = pagezone;
			spin_lock_irq(&zone->lru_lock);
		}
		BUG_ON(PageLRU(page));
		SetPageLRU(page);
		add_page_to_inactive_list(zone, page);
	}
	if (zone)
		spin_unlock_irq(&zone->lru_lock);
	release_pages(pvec->pages, pvec->nr, pvec->cold);
	pagevec_reinit(pvec);
}

EXPORT_SYMBOL(__pagevec_lru_add);

void __pagevec_lru_add_active(struct pagevec *pvec)
{
	int i;
	struct zone *zone = NULL;

	for (i = 0; i < pagevec_count(pvec); i++) {
		struct page *page = pvec->pages[i];
		struct zone *pagezone = page_zone(page);

		if (pagezone != zone) {
			if (zone)
				spin_unlock_irq(&zone->lru_lock);
			zone = pagezone;
			spin_lock_irq(&zone->lru_lock);
		}
		BUG_ON(PageLRU(page));
		SetPageLRU(page);
		BUG_ON(PageActive(page));
		SetPageActive(page);
		add_page_to_active_list(zone, page);
	}
	if (zone)
		spin_unlock_irq(&zone->lru_lock);
	release_pages(pvec->pages, pvec->nr, pvec->cold);
	pagevec_reinit(pvec);
}

/*
 * Try to drop buffers from the pages in a pagevec
 */
void pagevec_strip(struct pagevec *pvec)
{
	int i;

	for (i = 0; i < pagevec_count(pvec); i++) {
		struct page *page = pvec->pages[i];

		if (PagePrivate(page) && !TestSetPageLocked(page)) {
			if (PagePrivate(page))
				try_to_release_page(page, 0);
			unlock_page(page);
		}
	}
}

/**
 * pagevec_lookup - gang pagecache lookup
 * @pvec:	Where the resulting pages are placed
 * @mapping:	The address_space to search
 * @start:	The starting page index
 * @nr_pages:	The maximum number of pages
 *
 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
 * in the mapping.  The pages are placed in @pvec.  pagevec_lookup() takes a
 * reference against the pages in @pvec.
 *
 * The search returns a group of mapping-contiguous pages with ascending
 * indexes.  There may be holes in the indices due to not-present pages.
 *
 * pagevec_lookup() returns the number of pages which were found.
 */
unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
		pgoff_t start, unsigned nr_pages)
{
	pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
	return pagevec_count(pvec);
}

EXPORT_SYMBOL(pagevec_lookup);

unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
		pgoff_t *index, int tag, unsigned nr_pages)
{
	pvec->nr = find_get_pages_tag(mapping, index, tag,
					nr_pages, pvec->pages);
	return pagevec_count(pvec);
}

EXPORT_SYMBOL(pagevec_lookup_tag);

#ifdef CONFIG_SMP
/*
 * We tolerate a little inaccuracy to avoid ping-ponging the counter between
 * CPUs
 */
#define ACCT_THRESHOLD	max(16, NR_CPUS * 2)

static DEFINE_PER_CPU(long, committed_space) = 0;

void vm_acct_memory(long pages)
{
	long *local;

	preempt_disable();
	local = &__get_cpu_var(committed_space);
	*local += pages;
	if (*local > ACCT_THRESHOLD || *local < -ACCT_THRESHOLD) {
		atomic_add(*local, &vm_committed_space);
		*local = 0;
	}
	preempt_enable();
}

#ifdef CONFIG_HOTPLUG_CPU

/* Drop the CPU's cached committed space back into the central pool. */
static int cpu_swap_callback(struct notifier_block *nfb,
			     unsigned long action,
			     void *hcpu)
{
	long *committed;

	committed = &per_cpu(committed_space, (long)hcpu);
	if (action == CPU_DEAD) {
		atomic_add(*committed, &vm_committed_space);
		*committed = 0;
		__lru_add_drain((long)hcpu);
	}
	return NOTIFY_OK;
}
#endif /* CONFIG_HOTPLUG_CPU */
#endif /* CONFIG_SMP */

/*
 * Perform any setup for the swap system
 */
void __init swap_setup(void)
{
	unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);

	/* Use a smaller cluster for small-memory machines */
	if (megs < 16)
		page_cluster = 2;
	else
		page_cluster = 3;
	/*
	 * Right now other parts of the system means that we
	 * _really_ don't want to cluster much more
	 */
	hotcpu_notifier(cpu_swap_callback, 0);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/mm/swap.c
	3	*
	4	* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
	5	*/
	6
	7	/*
	8	* This file contains the default values for the opereation of the
	9	* Linux VM subsystem. Fine-tuning documentation can be found in
	10	* Documentation/sysctl/vm.txt.
	11	* Started 18.12.91
	12	* Swap aging added 23.2.95, Stephen Tweedie.
	13	* Buffermem limits added 12.3.98, Rik van Riel.
	14	*/
	15
	16	#include <linux/mm.h>
	17	#include <linux/sched.h>
	18	#include <linux/kernel_stat.h>
	19	#include <linux/swap.h>
	20	#include <linux/mman.h>
	21	#include <linux/pagemap.h>
	22	#include <linux/pagevec.h>
	23	#include <linux/init.h>
	24	#include <linux/module.h>
	25	#include <linux/mm_inline.h>
	26	#include <linux/buffer_head.h> /* for try_to_release_page() */
	27	#include <linux/module.h>
	28	#include <linux/percpu_counter.h>
	29	#include <linux/percpu.h>
	30	#include <linux/cpu.h>
	31	#include <linux/notifier.h>
	32	#include <linux/init.h>
	33
	34	/* How many pages do we try to swap or page in/out together? */
	35	int page_cluster;
	36
8519fb30	37	static void put_compound_page(struct page *page)
1da177e4	38	{
8519fb30 NP	39	page = (struct page *)page_private(page);
	40	if (put_page_testzero(page)) {
	41	void (dtor)(struct page page);
1da177e4	42
41d78ba5	43	dtor = (void ()(struct page ))page[1].lru.next;
8519fb30	44	(*dtor)(page);
1da177e4	45	}
8519fb30 NP	46	}
	47
	48	void put_page(struct page *page)
	49	{
	50	if (unlikely(PageCompound(page)))
	51	put_compound_page(page);
	52	else if (put_page_testzero(page))
1da177e4 LT	53	__page_cache_release(page);
	54	}
	55	EXPORT_SYMBOL(put_page);
1da177e4	56
1d7ea732 AZ	57	/**
	58	* put_pages_list(): release a list of pages
	59	*
	60	* Release a list of pages which are strung together on page.lru. Currently
	61	* used by read_cache_pages() and related error recovery code.
	62	*
	63	* @pages: list of pages threaded on page->lru
	64	*/
	65	void put_pages_list(struct list_head *pages)
	66	{
	67	while (!list_empty(pages)) {
	68	struct page *victim;
	69
	70	victim = list_entry(pages->prev, struct page, lru);
	71	list_del(&victim->lru);
	72	page_cache_release(victim);
	73	}
	74	}
	75	EXPORT_SYMBOL(put_pages_list);
	76
1da177e4 LT	77	/*
	78	* Writeback is about to end against a page which has been marked for immediate
	79	* reclaim. If it still appears to be reclaimable, move it to the tail of the
	80	* inactive list. The page still has PageWriteback set, which will pin it.
	81	*
	82	* We don't expect many pages to come through here, so don't bother batching
	83	* things up.
	84	*
	85	* To avoid placing the page at the tail of the LRU while PG_writeback is still
	86	* set, this function will clear PG_writeback before performing the page
	87	* motion. Do that inside the lru lock because once PG_writeback is cleared
	88	* we may not touch the page.
	89	*
	90	* Returns zero if it cleared PG_writeback.
	91	*/
	92	int rotate_reclaimable_page(struct page *page)
	93	{
	94	struct zone *zone;
	95	unsigned long flags;
	96
	97	if (PageLocked(page))
	98	return 1;
	99	if (PageDirty(page))
	100	return 1;
	101	if (PageActive(page))
	102	return 1;
	103	if (!PageLRU(page))
	104	return 1;
	105
	106	zone = page_zone(page);
	107	spin_lock_irqsave(&zone->lru_lock, flags);
	108	if (PageLRU(page) && !PageActive(page)) {
1bfba4e8	109	list_move_tail(&page->lru, &zone->inactive_list);
f8891e5e	110	__count_vm_event(PGROTATED);
1da177e4 LT	111	}
	112	if (!test_clear_page_writeback(page))
	113	BUG();
	114	spin_unlock_irqrestore(&zone->lru_lock, flags);
	115	return 0;
	116	}
	117
	118	/*
	119	* FIXME: speed this up?
	120	*/
	121	void fastcall activate_page(struct page *page)
	122	{
	123	struct zone *zone = page_zone(page);
	124
	125	spin_lock_irq(&zone->lru_lock);
	126	if (PageLRU(page) && !PageActive(page)) {
	127	del_page_from_inactive_list(zone, page);
	128	SetPageActive(page);
	129	add_page_to_active_list(zone, page);
f8891e5e	130	__count_vm_event(PGACTIVATE);
1da177e4 LT	131	}
	132	spin_unlock_irq(&zone->lru_lock);
	133	}
	134
	135	/*
	136	* Mark a page as having seen activity.
	137	*
	138	* inactive,unreferenced -> inactive,referenced
	139	* inactive,referenced -> active,unreferenced
	140	* active,unreferenced -> active,referenced
	141	*/
	142	void fastcall mark_page_accessed(struct page *page)
	143	{
	144	if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
	145	activate_page(page);
	146	ClearPageReferenced(page);
	147	} else if (!PageReferenced(page)) {
	148	SetPageReferenced(page);
	149	}
	150	}
	151
	152	EXPORT_SYMBOL(mark_page_accessed);
	153
	154	/**
	155	* lru_cache_add: add a page to the page lists
	156	* @page: the page to add
	157	*/
	158	static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
	159	static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };
	160
	161	void fastcall lru_cache_add(struct page *page)
	162	{
	163	struct pagevec *pvec = &get_cpu_var(lru_add_pvecs);
	164
	165	page_cache_get(page);
	166	if (!pagevec_add(pvec, page))
	167	__pagevec_lru_add(pvec);
	168	put_cpu_var(lru_add_pvecs);
	169	}
	170
	171	void fastcall lru_cache_add_active(struct page *page)
	172	{
	173	struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs);
	174
	175	page_cache_get(page);
	176	if (!pagevec_add(pvec, page))
	177	__pagevec_lru_add_active(pvec);
	178	put_cpu_var(lru_add_active_pvecs);
	179	}
	180
80bfed90	181	static void __lru_add_drain(int cpu)
1da177e4	182	{
80bfed90	183	struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu);
1da177e4	184
80bfed90	185	/* CPU is dead, so no locking needed. */
1da177e4 LT	186	if (pagevec_count(pvec))
1da177e4 LT	187	__pagevec_lru_add(pvec);
80bfed90	188	pvec = &per_cpu(lru_add_active_pvecs, cpu);
1da177e4 LT	189	if (pagevec_count(pvec))
1da177e4 LT	190	__pagevec_lru_add_active(pvec);
80bfed90 AM	191	}
	192
	193	void lru_add_drain(void)
	194	{
	195	__lru_add_drain(get_cpu());
	196	put_cpu();
1da177e4 LT	197	}
1da177e4 LT	198
053837fc NP	199	#ifdef CONFIG_NUMA
	200	static void lru_add_drain_per_cpu(void *dummy)
	201	{
	202	lru_add_drain();
	203	}
	204
	205	/*
	206	* Returns 0 for success
	207	*/
	208	int lru_add_drain_all(void)
	209	{
	210	return schedule_on_each_cpu(lru_add_drain_per_cpu, NULL);
	211	}
	212
	213	#else
	214
	215	/*
	216	* Returns 0 for success
	217	*/
	218	int lru_add_drain_all(void)
	219	{
	220	lru_add_drain();
	221	return 0;
	222	}
	223	#endif
	224
1da177e4 LT	225	/*
	226	* This path almost never happens for VM activity - pages are normally
	227	* freed via pagevecs. But it gets used by networking.
	228	*/
	229	void fastcall __page_cache_release(struct page *page)
	230	{
46453a6e NP	231	if (PageLRU(page)) {
	232	unsigned long flags;
	233	struct zone *zone = page_zone(page);
1da177e4	234
46453a6e	235	spin_lock_irqsave(&zone->lru_lock, flags);
8d438f96	236	BUG_ON(!PageLRU(page));
67453911	237	__ClearPageLRU(page);
1da177e4	238	del_page_from_lru(zone, page);
46453a6e NP	239	spin_unlock_irqrestore(&zone->lru_lock, flags);
	240	}
	241	free_hot_page(page);
1da177e4	242	}
1da177e4 LT	243	EXPORT_SYMBOL(__page_cache_release);
	244
	245	/*
	246	* Batched page_cache_release(). Decrement the reference count on all the
	247	* passed pages. If it fell to zero then remove the page from the LRU and
	248	* free it.
	249	*
	250	* Avoid taking zone->lru_lock if possible, but if it is taken, retain it
	251	* for the remainder of the operation.
	252	*
	253	* The locking in this function is against shrink_cache(): we recheck the
	254	* page count inside the lock to see whether shrink_cache grabbed the page
	255	* via the LRU. If it did, give up: shrink_cache will free it.
	256	*/
	257	void release_pages(struct page **pages, int nr, int cold)
	258	{
	259	int i;
	260	struct pagevec pages_to_free;
	261	struct zone *zone = NULL;
	262
	263	pagevec_init(&pages_to_free, cold);
	264	for (i = 0; i < nr; i++) {
	265	struct page *page = pages[i];
1da177e4	266
8519fb30 NP	267	if (unlikely(PageCompound(page))) {
	268	if (zone) {
	269	spin_unlock_irq(&zone->lru_lock);
	270	zone = NULL;
	271	}
	272	put_compound_page(page);
	273	continue;
	274	}
	275
b5810039	276	if (!put_page_testzero(page))
1da177e4 LT	277	continue;
1da177e4 LT	278
46453a6e NP	279	if (PageLRU(page)) {
	280	struct zone *pagezone = page_zone(page);
	281	if (pagezone != zone) {
	282	if (zone)
	283	spin_unlock_irq(&zone->lru_lock);
	284	zone = pagezone;
	285	spin_lock_irq(&zone->lru_lock);
	286	}
8d438f96	287	BUG_ON(!PageLRU(page));
67453911	288	__ClearPageLRU(page);
1da177e4	289	del_page_from_lru(zone, page);
46453a6e NP	290	}
	291
	292	if (!pagevec_add(&pages_to_free, page)) {
	293	if (zone) {
1da177e4	294	spin_unlock_irq(&zone->lru_lock);
46453a6e	295	zone = NULL;
1da177e4	296	}
46453a6e NP	297	__pagevec_free(&pages_to_free);
	298	pagevec_reinit(&pages_to_free);
	299	}
1da177e4 LT	300	}
	301	if (zone)
	302	spin_unlock_irq(&zone->lru_lock);
	303
	304	pagevec_free(&pages_to_free);
	305	}
	306
	307	/*
	308	* The pages which we're about to release may be in the deferred lru-addition
	309	* queues. That would prevent them from really being freed right now. That's
	310	* OK from a correctness point of view but is inefficient - those pages may be
	311	* cache-warm and we want to give them back to the page allocator ASAP.
	312	*
	313	* So __pagevec_release() will drain those queues here. __pagevec_lru_add()
	314	* and __pagevec_lru_add_active() call release_pages() directly to avoid
	315	* mutual recursion.
	316	*/
	317	void __pagevec_release(struct pagevec *pvec)
	318	{
	319	lru_add_drain();
	320	release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
	321	pagevec_reinit(pvec);
	322	}
	323
7f285701 SF	324	EXPORT_SYMBOL(__pagevec_release);
7f285701 SF	325
1da177e4 LT	326	/*
	327	* pagevec_release() for pages which are known to not be on the LRU
	328	*
	329	* This function reinitialises the caller's pagevec.
	330	*/
	331	void __pagevec_release_nonlru(struct pagevec *pvec)
	332	{
	333	int i;
	334	struct pagevec pages_to_free;
	335
	336	pagevec_init(&pages_to_free, pvec->cold);
1da177e4 LT	337	for (i = 0; i < pagevec_count(pvec); i++) {
	338	struct page *page = pvec->pages[i];
	339
	340	BUG_ON(PageLRU(page));
	341	if (put_page_testzero(page))
	342	pagevec_add(&pages_to_free, page);
	343	}
	344	pagevec_free(&pages_to_free);
	345	pagevec_reinit(pvec);
	346	}
	347
	348	/*
	349	* Add the passed pages to the LRU, then drop the caller's refcount
	350	* on them. Reinitialises the caller's pagevec.
	351	*/
	352	void __pagevec_lru_add(struct pagevec *pvec)
	353	{
	354	int i;
	355	struct zone *zone = NULL;
	356
	357	for (i = 0; i < pagevec_count(pvec); i++) {
	358	struct page *page = pvec->pages[i];
	359	struct zone *pagezone = page_zone(page);
	360
	361	if (pagezone != zone) {
	362	if (zone)
	363	spin_unlock_irq(&zone->lru_lock);
	364	zone = pagezone;
	365	spin_lock_irq(&zone->lru_lock);
	366	}
8d438f96 NP	367	BUG_ON(PageLRU(page));
8d438f96 NP	368	SetPageLRU(page);
1da177e4 LT	369	add_page_to_inactive_list(zone, page);
	370	}
	371	if (zone)
	372	spin_unlock_irq(&zone->lru_lock);
	373	release_pages(pvec->pages, pvec->nr, pvec->cold);
	374	pagevec_reinit(pvec);
	375	}
	376
	377	EXPORT_SYMBOL(__pagevec_lru_add);
	378
	379	void __pagevec_lru_add_active(struct pagevec *pvec)
	380	{
	381	int i;
	382	struct zone *zone = NULL;
	383
	384	for (i = 0; i < pagevec_count(pvec); i++) {
	385	struct page *page = pvec->pages[i];
	386	struct zone *pagezone = page_zone(page);
	387
	388	if (pagezone != zone) {
	389	if (zone)
	390	spin_unlock_irq(&zone->lru_lock);
	391	zone = pagezone;
	392	spin_lock_irq(&zone->lru_lock);
	393	}
8d438f96 NP	394	BUG_ON(PageLRU(page));
8d438f96 NP	395	SetPageLRU(page);
4c84cacf NP	396	BUG_ON(PageActive(page));
4c84cacf NP	397	SetPageActive(page);
1da177e4 LT	398	add_page_to_active_list(zone, page);
	399	}
	400	if (zone)
	401	spin_unlock_irq(&zone->lru_lock);
	402	release_pages(pvec->pages, pvec->nr, pvec->cold);
	403	pagevec_reinit(pvec);
	404	}
	405
	406	/*
	407	* Try to drop buffers from the pages in a pagevec
	408	*/
	409	void pagevec_strip(struct pagevec *pvec)
	410	{
	411	int i;
	412
	413	for (i = 0; i < pagevec_count(pvec); i++) {
	414	struct page *page = pvec->pages[i];
	415
	416	if (PagePrivate(page) && !TestSetPageLocked(page)) {
5b40dc78 CL	417	if (PagePrivate(page))
5b40dc78 CL	418	try_to_release_page(page, 0);
1da177e4 LT	419	unlock_page(page);
	420	}
	421	}
	422	}
	423
	424	/**
	425	* pagevec_lookup - gang pagecache lookup
	426	* @pvec: Where the resulting pages are placed
	427	* @mapping: The address_space to search
	428	* @start: The starting page index
	429	* @nr_pages: The maximum number of pages
	430	*
	431	* pagevec_lookup() will search for and return a group of up to @nr_pages pages
	432	* in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
	433	* reference against the pages in @pvec.
	434	*
	435	* The search returns a group of mapping-contiguous pages with ascending
	436	* indexes. There may be holes in the indices due to not-present pages.
	437	*
	438	* pagevec_lookup() returns the number of pages which were found.
	439	*/
	440	unsigned pagevec_lookup(struct pagevec pvec, struct address_space mapping,
	441	pgoff_t start, unsigned nr_pages)
	442	{
	443	pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
	444	return pagevec_count(pvec);
	445	}
	446
78539fdf CH	447	EXPORT_SYMBOL(pagevec_lookup);
78539fdf CH	448
1da177e4 LT	449	unsigned pagevec_lookup_tag(struct pagevec pvec, struct address_space mapping,
	450	pgoff_t *index, int tag, unsigned nr_pages)
	451	{
	452	pvec->nr = find_get_pages_tag(mapping, index, tag,
	453	nr_pages, pvec->pages);
	454	return pagevec_count(pvec);
	455	}
	456
7f285701	457	EXPORT_SYMBOL(pagevec_lookup_tag);
1da177e4 LT	458
	459	#ifdef CONFIG_SMP
	460	/*
	461	* We tolerate a little inaccuracy to avoid ping-ponging the counter between
	462	* CPUs
	463	*/
	464	#define ACCT_THRESHOLD max(16, NR_CPUS * 2)
	465
	466	static DEFINE_PER_CPU(long, committed_space) = 0;
	467
	468	void vm_acct_memory(long pages)
	469	{
	470	long *local;
	471
	472	preempt_disable();
	473	local = &__get_cpu_var(committed_space);
	474	*local += pages;
	475	if (local > ACCT_THRESHOLD \|\| local < -ACCT_THRESHOLD) {
	476	atomic_add(*local, &vm_committed_space);
	477	*local = 0;
	478	}
	479	preempt_enable();
	480	}
1da177e4 LT	481
1da177e4 LT	482	#ifdef CONFIG_HOTPLUG_CPU
1da177e4 LT	483
	484	/* Drop the CPU's cached committed space back into the central pool. */
	485	static int cpu_swap_callback(struct notifier_block *nfb,
	486	unsigned long action,
	487	void *hcpu)
	488	{
	489	long *committed;
	490
	491	committed = &per_cpu(committed_space, (long)hcpu);
	492	if (action == CPU_DEAD) {
	493	atomic_add(*committed, &vm_committed_space);
	494	*committed = 0;
80bfed90	495	__lru_add_drain((long)hcpu);
1da177e4 LT	496	}
	497	return NOTIFY_OK;
	498	}
	499	#endif /* CONFIG_HOTPLUG_CPU */
	500	#endif /* CONFIG_SMP */
	501
1da177e4 LT	502	/*
	503	* Perform any setup for the swap system
	504	*/
	505	void __init swap_setup(void)
	506	{
	507	unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);
	508
	509	/* Use a smaller cluster for small-memory machines */
	510	if (megs < 16)
	511	page_cluster = 2;
	512	else
	513	page_cluster = 3;
	514	/*
	515	* Right now other parts of the system means that we
	516	* _really_ don't want to cluster much more
	517	*/
	518	hotcpu_notifier(cpu_swap_callback, 0);
	519	}