[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);

/*
 * 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_del(&page->lru);
		list_add_tail(&page->lru, &zone->inactive_list);
		inc_page_state(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);
		inc_page_state(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 */

#ifdef CONFIG_SMP
void percpu_counter_mod(struct percpu_counter *fbc, long amount)
{
	long count;
	long *pcount;
	int cpu = get_cpu();

	pcount = per_cpu_ptr(fbc->counters, cpu);
	count = *pcount + amount;
	if (count >= FBC_BATCH || count <= -FBC_BATCH) {
		spin_lock(&fbc->lock);
		fbc->count += count;
		*pcount = 0;
		spin_unlock(&fbc->lock);
	} else {
		*pcount = count;
	}
	put_cpu();
}
EXPORT_SYMBOL(percpu_counter_mod);

/*
 * Add up all the per-cpu counts, return the result.  This is a more accurate
 * but much slower version of percpu_counter_read_positive()
 */
long percpu_counter_sum(struct percpu_counter *fbc)
{
	long ret;
	int cpu;

	spin_lock(&fbc->lock);
	ret = fbc->count;
	for_each_cpu(cpu) {
		long *pcount = per_cpu_ptr(fbc->counters, cpu);
		ret += *pcount;
	}
	spin_unlock(&fbc->lock);
	return ret < 0 ? 0 : ret;
}
EXPORT_SYMBOL(percpu_counter_sum);
#endif

/*
 * 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)) {
	89	list_del(&page->lru);
	90	list_add_tail(&page->lru, &zone->inactive_list);
	91	inc_page_state(pgrotated);
	92	}
	93	if (!test_clear_page_writeback(page))
	94	BUG();
	95	spin_unlock_irqrestore(&zone->lru_lock, flags);
	96	return 0;
	97	}
	98
	99	/*
	100	* FIXME: speed this up?
	101	*/
	102	void fastcall activate_page(struct page *page)
	103	{
	104	struct zone *zone = page_zone(page);
	105
	106	spin_lock_irq(&zone->lru_lock);
	107	if (PageLRU(page) && !PageActive(page)) {
	108	del_page_from_inactive_list(zone, page);
	109	SetPageActive(page);
	110	add_page_to_active_list(zone, page);
	111	inc_page_state(pgactivate);
	112	}
	113	spin_unlock_irq(&zone->lru_lock);
	114	}
	115
	116	/*
	117	* Mark a page as having seen activity.
	118	*
	119	* inactive,unreferenced -> inactive,referenced
120	* inactive,referenced -> active,unreferenced
121	* active,unreferenced -> active,referenced
122	*/
123	void fastcall mark_page_accessed(struct page *page)
124	{
125	if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
126	activate_page(page);
127	ClearPageReferenced(page);
128	} else if (!PageReferenced(page)) {
129	SetPageReferenced(page);
130	}
131	}
132
133	EXPORT_SYMBOL(mark_page_accessed);
134
135	/**
136	* lru_cache_add: add a page to the page lists
137	* @page: the page to add
138	*/
139	static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
140	static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };
141
142	void fastcall lru_cache_add(struct page *page)
143	{
144	struct pagevec *pvec = &get_cpu_var(lru_add_pvecs);
145
146	page_cache_get(page);
147	if (!pagevec_add(pvec, page))
148	__pagevec_lru_add(pvec);
149	put_cpu_var(lru_add_pvecs);
150	}
151
152	void fastcall lru_cache_add_active(struct page *page)
153	{
154	struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs);
155
156	page_cache_get(page);
157	if (!pagevec_add(pvec, page))
158	__pagevec_lru_add_active(pvec);
159	put_cpu_var(lru_add_active_pvecs);
160	}
161
80bfed90	162	static void __lru_add_drain(int cpu)
1da177e4	163	{
80bfed90	164	struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu);
1da177e4	165
80bfed90	166	/* CPU is dead, so no locking needed. */
1da177e4 LT	167	if (pagevec_count(pvec))
1da177e4 LT	168	__pagevec_lru_add(pvec);
80bfed90	169	pvec = &per_cpu(lru_add_active_pvecs, cpu);
1da177e4 LT	170	if (pagevec_count(pvec))
1da177e4 LT	171	__pagevec_lru_add_active(pvec);
80bfed90 AM	172	}
	173
	174	void lru_add_drain(void)
	175	{
	176	__lru_add_drain(get_cpu());
	177	put_cpu();
1da177e4 LT	178	}
1da177e4 LT	179
053837fc NP	180	#ifdef CONFIG_NUMA
	181	static void lru_add_drain_per_cpu(void *dummy)
	182	{
	183	lru_add_drain();
	184	}
	185
	186	/*
	187	* Returns 0 for success
	188	*/
	189	int lru_add_drain_all(void)
	190	{
	191	return schedule_on_each_cpu(lru_add_drain_per_cpu, NULL);
	192	}
	193
	194	#else
	195
	196	/*
	197	* Returns 0 for success
	198	*/
	199	int lru_add_drain_all(void)
	200	{
	201	lru_add_drain();
	202	return 0;
	203	}
	204	#endif
	205
1da177e4 LT	206	/*
	207	* This path almost never happens for VM activity - pages are normally
	208	* freed via pagevecs. But it gets used by networking.
	209	*/
	210	void fastcall __page_cache_release(struct page *page)
	211	{
46453a6e NP	212	if (PageLRU(page)) {
	213	unsigned long flags;
	214	struct zone *zone = page_zone(page);
1da177e4	215
46453a6e	216	spin_lock_irqsave(&zone->lru_lock, flags);
8d438f96 NP	217	BUG_ON(!PageLRU(page));
8d438f96 NP	218	ClearPageLRU(page);
1da177e4	219	del_page_from_lru(zone, page);
46453a6e NP	220	spin_unlock_irqrestore(&zone->lru_lock, flags);
	221	}
	222	free_hot_page(page);
1da177e4	223	}
1da177e4 LT	224	EXPORT_SYMBOL(__page_cache_release);
	225
	226	/*
	227	* Batched page_cache_release(). Decrement the reference count on all the
	228	* passed pages. If it fell to zero then remove the page from the LRU and
	229	* free it.
	230	*
	231	* Avoid taking zone->lru_lock if possible, but if it is taken, retain it
	232	* for the remainder of the operation.
	233	*
	234	* The locking in this function is against shrink_cache(): we recheck the
	235	* page count inside the lock to see whether shrink_cache grabbed the page
	236	* via the LRU. If it did, give up: shrink_cache will free it.
	237	*/
	238	void release_pages(struct page **pages, int nr, int cold)
	239	{
	240	int i;
	241	struct pagevec pages_to_free;
	242	struct zone *zone = NULL;
	243
	244	pagevec_init(&pages_to_free, cold);
	245	for (i = 0; i < nr; i++) {
	246	struct page *page = pages[i];
1da177e4	247
8519fb30 NP	248	if (unlikely(PageCompound(page))) {
	249	if (zone) {
	250	spin_unlock_irq(&zone->lru_lock);
	251	zone = NULL;
	252	}
	253	put_compound_page(page);
	254	continue;
	255	}
	256
b5810039	257	if (!put_page_testzero(page))
1da177e4 LT	258	continue;
1da177e4 LT	259
46453a6e NP	260	if (PageLRU(page)) {
	261	struct zone *pagezone = page_zone(page);
	262	if (pagezone != zone) {
	263	if (zone)
	264	spin_unlock_irq(&zone->lru_lock);
	265	zone = pagezone;
	266	spin_lock_irq(&zone->lru_lock);
	267	}
8d438f96 NP	268	BUG_ON(!PageLRU(page));
8d438f96 NP	269	ClearPageLRU(page);
1da177e4	270	del_page_from_lru(zone, page);
46453a6e NP	271	}
	272
	273	if (!pagevec_add(&pages_to_free, page)) {
	274	if (zone) {
1da177e4	275	spin_unlock_irq(&zone->lru_lock);
46453a6e	276	zone = NULL;
1da177e4	277	}
46453a6e NP	278	__pagevec_free(&pages_to_free);
	279	pagevec_reinit(&pages_to_free);
	280	}
1da177e4 LT	281	}
	282	if (zone)
	283	spin_unlock_irq(&zone->lru_lock);
	284
	285	pagevec_free(&pages_to_free);
	286	}
	287
	288	/*
	289	* The pages which we're about to release may be in the deferred lru-addition
	290	* queues. That would prevent them from really being freed right now. That's
	291	* OK from a correctness point of view but is inefficient - those pages may be
	292	* cache-warm and we want to give them back to the page allocator ASAP.
	293	*
	294	* So __pagevec_release() will drain those queues here. __pagevec_lru_add()
	295	* and __pagevec_lru_add_active() call release_pages() directly to avoid
	296	* mutual recursion.
	297	*/
	298	void __pagevec_release(struct pagevec *pvec)
	299	{
	300	lru_add_drain();
	301	release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
	302	pagevec_reinit(pvec);
	303	}
	304
7f285701 SF	305	EXPORT_SYMBOL(__pagevec_release);
7f285701 SF	306
1da177e4 LT	307	/*
	308	* pagevec_release() for pages which are known to not be on the LRU
	309	*
	310	* This function reinitialises the caller's pagevec.
	311	*/
	312	void __pagevec_release_nonlru(struct pagevec *pvec)
	313	{
	314	int i;
	315	struct pagevec pages_to_free;
	316
	317	pagevec_init(&pages_to_free, pvec->cold);
1da177e4 LT	318	for (i = 0; i < pagevec_count(pvec); i++) {
	319	struct page *page = pvec->pages[i];
	320
	321	BUG_ON(PageLRU(page));
	322	if (put_page_testzero(page))
	323	pagevec_add(&pages_to_free, page);
	324	}
	325	pagevec_free(&pages_to_free);
	326	pagevec_reinit(pvec);
	327	}
	328
	329	/*
	330	* Add the passed pages to the LRU, then drop the caller's refcount
	331	* on them. Reinitialises the caller's pagevec.
	332	*/
	333	void __pagevec_lru_add(struct pagevec *pvec)
	334	{
	335	int i;
	336	struct zone *zone = NULL;
	337
	338	for (i = 0; i < pagevec_count(pvec); i++) {
	339	struct page *page = pvec->pages[i];
	340	struct zone *pagezone = page_zone(page);
	341
	342	if (pagezone != zone) {
	343	if (zone)
	344	spin_unlock_irq(&zone->lru_lock);
	345	zone = pagezone;
	346	spin_lock_irq(&zone->lru_lock);
	347	}
8d438f96 NP	348	BUG_ON(PageLRU(page));
8d438f96 NP	349	SetPageLRU(page);
1da177e4 LT	350	add_page_to_inactive_list(zone, page);
	351	}
	352	if (zone)
	353	spin_unlock_irq(&zone->lru_lock);
	354	release_pages(pvec->pages, pvec->nr, pvec->cold);
	355	pagevec_reinit(pvec);
	356	}
	357
	358	EXPORT_SYMBOL(__pagevec_lru_add);
	359
	360	void __pagevec_lru_add_active(struct pagevec *pvec)
	361	{
	362	int i;
	363	struct zone *zone = NULL;
	364
	365	for (i = 0; i < pagevec_count(pvec); i++) {
	366	struct page *page = pvec->pages[i];
	367	struct zone *pagezone = page_zone(page);
	368
	369	if (pagezone != zone) {
	370	if (zone)
	371	spin_unlock_irq(&zone->lru_lock);
	372	zone = pagezone;
	373	spin_lock_irq(&zone->lru_lock);
	374	}
8d438f96 NP	375	BUG_ON(PageLRU(page));
8d438f96 NP	376	SetPageLRU(page);
4c84cacf NP	377	BUG_ON(PageActive(page));
4c84cacf NP	378	SetPageActive(page);
1da177e4 LT	379	add_page_to_active_list(zone, page);
	380	}
	381	if (zone)
	382	spin_unlock_irq(&zone->lru_lock);
	383	release_pages(pvec->pages, pvec->nr, pvec->cold);
	384	pagevec_reinit(pvec);
	385	}
	386
	387	/*
	388	* Try to drop buffers from the pages in a pagevec
	389	*/
	390	void pagevec_strip(struct pagevec *pvec)
	391	{
	392	int i;
	393
	394	for (i = 0; i < pagevec_count(pvec); i++) {
	395	struct page *page = pvec->pages[i];
	396
	397	if (PagePrivate(page) && !TestSetPageLocked(page)) {
5b40dc78 CL	398	if (PagePrivate(page))
5b40dc78 CL	399	try_to_release_page(page, 0);
1da177e4 LT	400	unlock_page(page);
	401	}
	402	}
	403	}
	404
	405	/**
	406	* pagevec_lookup - gang pagecache lookup
	407	* @pvec: Where the resulting pages are placed
	408	* @mapping: The address_space to search
	409	* @start: The starting page index
	410	* @nr_pages: The maximum number of pages
	411	*
	412	* pagevec_lookup() will search for and return a group of up to @nr_pages pages
	413	* in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
	414	* reference against the pages in @pvec.
	415	*
	416	* The search returns a group of mapping-contiguous pages with ascending
	417	* indexes. There may be holes in the indices due to not-present pages.
	418	*
	419	* pagevec_lookup() returns the number of pages which were found.
	420	*/
	421	unsigned pagevec_lookup(struct pagevec pvec, struct address_space mapping,
	422	pgoff_t start, unsigned nr_pages)
	423	{
	424	pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
	425	return pagevec_count(pvec);
	426	}
	427
78539fdf CH	428	EXPORT_SYMBOL(pagevec_lookup);
78539fdf CH	429
1da177e4 LT	430	unsigned pagevec_lookup_tag(struct pagevec pvec, struct address_space mapping,
	431	pgoff_t *index, int tag, unsigned nr_pages)
	432	{
	433	pvec->nr = find_get_pages_tag(mapping, index, tag,
	434	nr_pages, pvec->pages);
	435	return pagevec_count(pvec);
	436	}
	437
7f285701	438	EXPORT_SYMBOL(pagevec_lookup_tag);
1da177e4 LT	439
	440	#ifdef CONFIG_SMP
	441	/*
	442	* We tolerate a little inaccuracy to avoid ping-ponging the counter between
	443	* CPUs
	444	*/
	445	#define ACCT_THRESHOLD max(16, NR_CPUS * 2)
	446
	447	static DEFINE_PER_CPU(long, committed_space) = 0;
	448
	449	void vm_acct_memory(long pages)
	450	{
	451	long *local;
	452
	453	preempt_disable();
	454	local = &__get_cpu_var(committed_space);
	455	*local += pages;
	456	if (local > ACCT_THRESHOLD \|\| local < -ACCT_THRESHOLD) {
	457	atomic_add(*local, &vm_committed_space);
	458	*local = 0;
	459	}
	460	preempt_enable();
	461	}
1da177e4 LT	462
1da177e4 LT	463	#ifdef CONFIG_HOTPLUG_CPU
1da177e4 LT	464
	465	/* Drop the CPU's cached committed space back into the central pool. */
	466	static int cpu_swap_callback(struct notifier_block *nfb,
	467	unsigned long action,
	468	void *hcpu)
	469	{
	470	long *committed;
	471
	472	committed = &per_cpu(committed_space, (long)hcpu);
	473	if (action == CPU_DEAD) {
	474	atomic_add(*committed, &vm_committed_space);
	475	*committed = 0;
80bfed90	476	__lru_add_drain((long)hcpu);
1da177e4 LT	477	}
	478	return NOTIFY_OK;
	479	}
	480	#endif /* CONFIG_HOTPLUG_CPU */
	481	#endif /* CONFIG_SMP */
	482
	483	#ifdef CONFIG_SMP
	484	void percpu_counter_mod(struct percpu_counter *fbc, long amount)
	485	{
	486	long count;
	487	long *pcount;
	488	int cpu = get_cpu();
	489
	490	pcount = per_cpu_ptr(fbc->counters, cpu);
	491	count = *pcount + amount;
	492	if (count >= FBC_BATCH \|\| count <= -FBC_BATCH) {
	493	spin_lock(&fbc->lock);
	494	fbc->count += count;
e2bab3d9	495	*pcount = 0;
1da177e4	496	spin_unlock(&fbc->lock);
e2bab3d9 AM	497	} else {
e2bab3d9 AM	498	*pcount = count;
1da177e4	499	}
1da177e4 LT	500	put_cpu();
	501	}
	502	EXPORT_SYMBOL(percpu_counter_mod);
e2bab3d9 AM	503
	504	/*
	505	* Add up all the per-cpu counts, return the result. This is a more accurate
	506	* but much slower version of percpu_counter_read_positive()
	507	*/
	508	long percpu_counter_sum(struct percpu_counter *fbc)
	509	{
	510	long ret;
	511	int cpu;
	512
	513	spin_lock(&fbc->lock);
	514	ret = fbc->count;
	515	for_each_cpu(cpu) {
	516	long *pcount = per_cpu_ptr(fbc->counters, cpu);
	517	ret += *pcount;
	518	}
	519	spin_unlock(&fbc->lock);
	520	return ret < 0 ? 0 : ret;
	521	}
	522	EXPORT_SYMBOL(percpu_counter_sum);
1da177e4 LT	523	#endif
	524
	525	/*
	526	* Perform any setup for the swap system
	527	*/
	528	void __init swap_setup(void)
	529	{
	530	unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);
	531
	532	/* Use a smaller cluster for small-memory machines */
	533	if (megs < 16)
	534	page_cluster = 2;
	535	else
	536	page_cluster = 3;
	537	/*
	538	* Right now other parts of the system means that we
	539	* _really_ don't want to cluster much more
	540	*/
	541	hotcpu_notifier(cpu_swap_callback, 0);
	542	}