[linux-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;

/*
 * This path almost never happens for VM activity - pages are normally
 * freed via pagevecs.  But it gets used by networking.
 */
static 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);
		VM_BUG_ON(!PageLRU(page));
		__ClearPageLRU(page);
		del_page_from_lru(zone, page);
		spin_unlock_irqrestore(&zone->lru_lock, flags);
	}
	free_hot_page(page);
}

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

/*
 * 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);
			}
			VM_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];

		VM_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);
		}
		VM_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);
		}
		VM_BUG_ON(PageLRU(page));
		SetPageLRU(page);
		VM_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
b221385b AB	37	/*
	38	* This path almost never happens for VM activity - pages are normally
	39	* freed via pagevecs. But it gets used by networking.
	40	*/
	41	static void fastcall __page_cache_release(struct page *page)
	42	{
	43	if (PageLRU(page)) {
	44	unsigned long flags;
	45	struct zone *zone = page_zone(page);
	46
	47	spin_lock_irqsave(&zone->lru_lock, flags);
	48	VM_BUG_ON(!PageLRU(page));
	49	__ClearPageLRU(page);
	50	del_page_from_lru(zone, page);
	51	spin_unlock_irqrestore(&zone->lru_lock, flags);
	52	}
	53	free_hot_page(page);
	54	}
	55
8519fb30	56	static void put_compound_page(struct page *page)
1da177e4	57	{
8519fb30 NP	58	page = (struct page *)page_private(page);
	59	if (put_page_testzero(page)) {
	60	void (dtor)(struct page page);
1da177e4	61
41d78ba5	62	dtor = (void ()(struct page ))page[1].lru.next;
8519fb30	63	(*dtor)(page);
1da177e4	64	}
8519fb30 NP	65	}
	66
	67	void put_page(struct page *page)
	68	{
	69	if (unlikely(PageCompound(page)))
	70	put_compound_page(page);
	71	else if (put_page_testzero(page))
1da177e4 LT	72	__page_cache_release(page);
	73	}
	74	EXPORT_SYMBOL(put_page);
1da177e4	75
1d7ea732 AZ	76	/**
	77	* put_pages_list(): release a list of pages
	78	*
	79	* Release a list of pages which are strung together on page.lru. Currently
	80	* used by read_cache_pages() and related error recovery code.
	81	*
	82	* @pages: list of pages threaded on page->lru
	83	*/
	84	void put_pages_list(struct list_head *pages)
	85	{
	86	while (!list_empty(pages)) {
	87	struct page *victim;
	88
	89	victim = list_entry(pages->prev, struct page, lru);
	90	list_del(&victim->lru);
	91	page_cache_release(victim);
	92	}
	93	}
	94	EXPORT_SYMBOL(put_pages_list);
	95
1da177e4 LT	96	/*
	97	* Writeback is about to end against a page which has been marked for immediate
	98	* reclaim. If it still appears to be reclaimable, move it to the tail of the
	99	* inactive list. The page still has PageWriteback set, which will pin it.
	100	*
	101	* We don't expect many pages to come through here, so don't bother batching
	102	* things up.
	103	*
	104	* To avoid placing the page at the tail of the LRU while PG_writeback is still
	105	* set, this function will clear PG_writeback before performing the page
	106	* motion. Do that inside the lru lock because once PG_writeback is cleared
	107	* we may not touch the page.
	108	*
	109	* Returns zero if it cleared PG_writeback.
	110	*/
	111	int rotate_reclaimable_page(struct page *page)
	112	{
	113	struct zone *zone;
	114	unsigned long flags;
	115
	116	if (PageLocked(page))
	117	return 1;
	118	if (PageDirty(page))
	119	return 1;
	120	if (PageActive(page))
	121	return 1;
	122	if (!PageLRU(page))
	123	return 1;
	124
	125	zone = page_zone(page);
	126	spin_lock_irqsave(&zone->lru_lock, flags);
	127	if (PageLRU(page) && !PageActive(page)) {
1bfba4e8	128	list_move_tail(&page->lru, &zone->inactive_list);
f8891e5e	129	__count_vm_event(PGROTATED);
1da177e4 LT	130	}
	131	if (!test_clear_page_writeback(page))
	132	BUG();
	133	spin_unlock_irqrestore(&zone->lru_lock, flags);
	134	return 0;
	135	}
	136
	137	/*
	138	* FIXME: speed this up?
	139	*/
	140	void fastcall activate_page(struct page *page)
	141	{
	142	struct zone *zone = page_zone(page);
	143
	144	spin_lock_irq(&zone->lru_lock);
	145	if (PageLRU(page) && !PageActive(page)) {
	146	del_page_from_inactive_list(zone, page);
	147	SetPageActive(page);
	148	add_page_to_active_list(zone, page);
f8891e5e	149	__count_vm_event(PGACTIVATE);
1da177e4 LT	150	}
	151	spin_unlock_irq(&zone->lru_lock);
	152	}
	153
	154	/*
	155	* Mark a page as having seen activity.
	156	*
	157	* inactive,unreferenced -> inactive,referenced
	158	* inactive,referenced -> active,unreferenced
	159	* active,unreferenced -> active,referenced
	160	*/
	161	void fastcall mark_page_accessed(struct page *page)
	162	{
	163	if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
	164	activate_page(page);
	165	ClearPageReferenced(page);
	166	} else if (!PageReferenced(page)) {
	167	SetPageReferenced(page);
	168	}
	169	}
	170
	171	EXPORT_SYMBOL(mark_page_accessed);
	172
	173	/**
	174	* lru_cache_add: add a page to the page lists
	175	* @page: the page to add
	176	*/
	177	static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
	178	static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };
	179
	180	void fastcall lru_cache_add(struct page *page)
	181	{
	182	struct pagevec *pvec = &get_cpu_var(lru_add_pvecs);
	183
	184	page_cache_get(page);
	185	if (!pagevec_add(pvec, page))
	186	__pagevec_lru_add(pvec);
	187	put_cpu_var(lru_add_pvecs);
	188	}
	189
	190	void fastcall lru_cache_add_active(struct page *page)
	191	{
	192	struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs);
	193
	194	page_cache_get(page);
	195	if (!pagevec_add(pvec, page))
	196	__pagevec_lru_add_active(pvec);
	197	put_cpu_var(lru_add_active_pvecs);
	198	}
	199
80bfed90	200	static void __lru_add_drain(int cpu)
1da177e4	201	{
80bfed90	202	struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu);
1da177e4	203
80bfed90	204	/* CPU is dead, so no locking needed. */
1da177e4 LT	205	if (pagevec_count(pvec))
1da177e4 LT	206	__pagevec_lru_add(pvec);
80bfed90	207	pvec = &per_cpu(lru_add_active_pvecs, cpu);
1da177e4 LT	208	if (pagevec_count(pvec))
1da177e4 LT	209	__pagevec_lru_add_active(pvec);
80bfed90 AM	210	}
	211
	212	void lru_add_drain(void)
	213	{
	214	__lru_add_drain(get_cpu());
	215	put_cpu();
1da177e4 LT	216	}
1da177e4 LT	217
053837fc NP	218	#ifdef CONFIG_NUMA
	219	static void lru_add_drain_per_cpu(void *dummy)
	220	{
	221	lru_add_drain();
	222	}
	223
	224	/*
	225	* Returns 0 for success
	226	*/
	227	int lru_add_drain_all(void)
	228	{
	229	return schedule_on_each_cpu(lru_add_drain_per_cpu, NULL);
	230	}
	231
	232	#else
	233
	234	/*
	235	* Returns 0 for success
	236	*/
	237	int lru_add_drain_all(void)
	238	{
	239	lru_add_drain();
	240	return 0;
	241	}
	242	#endif
	243
1da177e4 LT	244	/*
	245	* Batched page_cache_release(). Decrement the reference count on all the
	246	* passed pages. If it fell to zero then remove the page from the LRU and
	247	* free it.
	248	*
	249	* Avoid taking zone->lru_lock if possible, but if it is taken, retain it
	250	* for the remainder of the operation.
	251	*
	252	* The locking in this function is against shrink_cache(): we recheck the
	253	* page count inside the lock to see whether shrink_cache grabbed the page
	254	* via the LRU. If it did, give up: shrink_cache will free it.
	255	*/
	256	void release_pages(struct page **pages, int nr, int cold)
	257	{
	258	int i;
	259	struct pagevec pages_to_free;
	260	struct zone *zone = NULL;
	261
	262	pagevec_init(&pages_to_free, cold);
	263	for (i = 0; i < nr; i++) {
	264	struct page *page = pages[i];
1da177e4	265
8519fb30 NP	266	if (unlikely(PageCompound(page))) {
	267	if (zone) {
	268	spin_unlock_irq(&zone->lru_lock);
	269	zone = NULL;
	270	}
	271	put_compound_page(page);
	272	continue;
	273	}
	274
b5810039	275	if (!put_page_testzero(page))
1da177e4 LT	276	continue;
1da177e4 LT	277
46453a6e NP	278	if (PageLRU(page)) {
	279	struct zone *pagezone = page_zone(page);
	280	if (pagezone != zone) {
	281	if (zone)
	282	spin_unlock_irq(&zone->lru_lock);
	283	zone = pagezone;
	284	spin_lock_irq(&zone->lru_lock);
	285	}
725d704e	286	VM_BUG_ON(!PageLRU(page));
67453911	287	__ClearPageLRU(page);
1da177e4	288	del_page_from_lru(zone, page);
46453a6e NP	289	}
	290
	291	if (!pagevec_add(&pages_to_free, page)) {
	292	if (zone) {
1da177e4	293	spin_unlock_irq(&zone->lru_lock);
46453a6e	294	zone = NULL;
1da177e4	295	}
46453a6e NP	296	__pagevec_free(&pages_to_free);
	297	pagevec_reinit(&pages_to_free);
	298	}
1da177e4 LT	299	}
	300	if (zone)
	301	spin_unlock_irq(&zone->lru_lock);
	302
	303	pagevec_free(&pages_to_free);
	304	}
	305
	306	/*
	307	* The pages which we're about to release may be in the deferred lru-addition
	308	* queues. That would prevent them from really being freed right now. That's
	309	* OK from a correctness point of view but is inefficient - those pages may be
	310	* cache-warm and we want to give them back to the page allocator ASAP.
	311	*
	312	* So __pagevec_release() will drain those queues here. __pagevec_lru_add()
	313	* and __pagevec_lru_add_active() call release_pages() directly to avoid
	314	* mutual recursion.
	315	*/
	316	void __pagevec_release(struct pagevec *pvec)
	317	{
	318	lru_add_drain();
	319	release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
	320	pagevec_reinit(pvec);
	321	}
	322
7f285701 SF	323	EXPORT_SYMBOL(__pagevec_release);
7f285701 SF	324
1da177e4 LT	325	/*
	326	* pagevec_release() for pages which are known to not be on the LRU
	327	*
	328	* This function reinitialises the caller's pagevec.
	329	*/
	330	void __pagevec_release_nonlru(struct pagevec *pvec)
	331	{
	332	int i;
	333	struct pagevec pages_to_free;
	334
	335	pagevec_init(&pages_to_free, pvec->cold);
1da177e4 LT	336	for (i = 0; i < pagevec_count(pvec); i++) {
	337	struct page *page = pvec->pages[i];
	338
725d704e	339	VM_BUG_ON(PageLRU(page));
1da177e4 LT	340	if (put_page_testzero(page))
	341	pagevec_add(&pages_to_free, page);
	342	}
	343	pagevec_free(&pages_to_free);
	344	pagevec_reinit(pvec);
	345	}
	346
	347	/*
	348	* Add the passed pages to the LRU, then drop the caller's refcount
	349	* on them. Reinitialises the caller's pagevec.
	350	*/
	351	void __pagevec_lru_add(struct pagevec *pvec)
	352	{
	353	int i;
	354	struct zone *zone = NULL;
	355
	356	for (i = 0; i < pagevec_count(pvec); i++) {
	357	struct page *page = pvec->pages[i];
	358	struct zone *pagezone = page_zone(page);
	359
	360	if (pagezone != zone) {
	361	if (zone)
	362	spin_unlock_irq(&zone->lru_lock);
	363	zone = pagezone;
	364	spin_lock_irq(&zone->lru_lock);
	365	}
725d704e	366	VM_BUG_ON(PageLRU(page));
8d438f96	367	SetPageLRU(page);
1da177e4 LT	368	add_page_to_inactive_list(zone, page);
	369	}
	370	if (zone)
	371	spin_unlock_irq(&zone->lru_lock);
	372	release_pages(pvec->pages, pvec->nr, pvec->cold);
	373	pagevec_reinit(pvec);
	374	}
	375
	376	EXPORT_SYMBOL(__pagevec_lru_add);
	377
	378	void __pagevec_lru_add_active(struct pagevec *pvec)
	379	{
	380	int i;
	381	struct zone *zone = NULL;
	382
	383	for (i = 0; i < pagevec_count(pvec); i++) {
	384	struct page *page = pvec->pages[i];
	385	struct zone *pagezone = page_zone(page);
	386
	387	if (pagezone != zone) {
	388	if (zone)
	389	spin_unlock_irq(&zone->lru_lock);
	390	zone = pagezone;
	391	spin_lock_irq(&zone->lru_lock);
	392	}
725d704e	393	VM_BUG_ON(PageLRU(page));
8d438f96	394	SetPageLRU(page);
725d704e	395	VM_BUG_ON(PageActive(page));
4c84cacf	396	SetPageActive(page);
1da177e4 LT	397	add_page_to_active_list(zone, page);
	398	}
	399	if (zone)
	400	spin_unlock_irq(&zone->lru_lock);
	401	release_pages(pvec->pages, pvec->nr, pvec->cold);
	402	pagevec_reinit(pvec);
	403	}
	404
	405	/*
	406	* Try to drop buffers from the pages in a pagevec
	407	*/
	408	void pagevec_strip(struct pagevec *pvec)
	409	{
	410	int i;
	411
	412	for (i = 0; i < pagevec_count(pvec); i++) {
	413	struct page *page = pvec->pages[i];
	414
	415	if (PagePrivate(page) && !TestSetPageLocked(page)) {
5b40dc78 CL	416	if (PagePrivate(page))
5b40dc78 CL	417	try_to_release_page(page, 0);
1da177e4 LT	418	unlock_page(page);
	419	}
	420	}
	421	}
	422
	423	/**
	424	* pagevec_lookup - gang pagecache lookup
	425	* @pvec: Where the resulting pages are placed
	426	* @mapping: The address_space to search
	427	* @start: The starting page index
	428	* @nr_pages: The maximum number of pages
	429	*
	430	* pagevec_lookup() will search for and return a group of up to @nr_pages pages
	431	* in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
	432	* reference against the pages in @pvec.
	433	*
	434	* The search returns a group of mapping-contiguous pages with ascending
	435	* indexes. There may be holes in the indices due to not-present pages.
	436	*
	437	* pagevec_lookup() returns the number of pages which were found.
	438	*/
	439	unsigned pagevec_lookup(struct pagevec pvec, struct address_space mapping,
	440	pgoff_t start, unsigned nr_pages)
	441	{
	442	pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
	443	return pagevec_count(pvec);
	444	}
	445
78539fdf CH	446	EXPORT_SYMBOL(pagevec_lookup);
78539fdf CH	447
1da177e4 LT	448	unsigned pagevec_lookup_tag(struct pagevec pvec, struct address_space mapping,
	449	pgoff_t *index, int tag, unsigned nr_pages)
	450	{
	451	pvec->nr = find_get_pages_tag(mapping, index, tag,
	452	nr_pages, pvec->pages);
	453	return pagevec_count(pvec);
	454	}
	455
7f285701	456	EXPORT_SYMBOL(pagevec_lookup_tag);
1da177e4 LT	457
	458	#ifdef CONFIG_SMP
	459	/*
	460	* We tolerate a little inaccuracy to avoid ping-ponging the counter between
	461	* CPUs
	462	*/
	463	#define ACCT_THRESHOLD max(16, NR_CPUS * 2)
	464
	465	static DEFINE_PER_CPU(long, committed_space) = 0;
	466
	467	void vm_acct_memory(long pages)
	468	{
	469	long *local;
	470
	471	preempt_disable();
	472	local = &__get_cpu_var(committed_space);
	473	*local += pages;
	474	if (local > ACCT_THRESHOLD \|\| local < -ACCT_THRESHOLD) {
	475	atomic_add(*local, &vm_committed_space);
	476	*local = 0;
	477	}
	478	preempt_enable();
	479	}
1da177e4 LT	480
1da177e4 LT	481	#ifdef CONFIG_HOTPLUG_CPU
1da177e4 LT	482
	483	/* Drop the CPU's cached committed space back into the central pool. */
	484	static int cpu_swap_callback(struct notifier_block *nfb,
	485	unsigned long action,
	486	void *hcpu)
	487	{
	488	long *committed;
	489
	490	committed = &per_cpu(committed_space, (long)hcpu);
	491	if (action == CPU_DEAD) {
	492	atomic_add(*committed, &vm_committed_space);
	493	*committed = 0;
80bfed90	494	__lru_add_drain((long)hcpu);
1da177e4 LT	495	}
	496	return NOTIFY_OK;
	497	}
	498	#endif /* CONFIG_HOTPLUG_CPU */
	499	#endif /* CONFIG_SMP */
	500
1da177e4 LT	501	/*
	502	* Perform any setup for the swap system
	503	*/
	504	void __init swap_setup(void)
	505	{
	506	unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);
	507
	508	/* Use a smaller cluster for small-memory machines */
	509	if (megs < 16)
	510	page_cluster = 2;
	511	else
	512	page_cluster = 3;
	513	/*
	514	* Right now other parts of the system means that we
	515	* _really_ don't want to cluster much more
	516	*/
	517	hotcpu_notifier(cpu_swap_callback, 0);
	518	}