[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;

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);

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