[net-next-2.6.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/percpu_counter.h>
#include <linux/percpu.h>
#include <linux/cpu.h>
#include <linux/notifier.h>

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

static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };
static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs) = { 0, };

/*
 * 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 = compound_head(page);
	if (put_page_testzero(page)) {
		compound_page_dtor *dtor;

		dtor = get_compound_page_dtor(page);
		(*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);

/*
 * pagevec_move_tail() must be called with IRQ disabled.
 * Otherwise this may cause nasty races.
 */
static void pagevec_move_tail(struct pagevec *pvec)
{
	int i;
	int pgmoved = 0;
	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(&zone->lru_lock);
			zone = pagezone;
			spin_lock(&zone->lru_lock);
		}
		if (PageLRU(page) && !PageActive(page)) {
			list_move_tail(&page->lru, &zone->inactive_list);
			pgmoved++;
		}
	}
	if (zone)
		spin_unlock(&zone->lru_lock);
	__count_vm_events(PGROTATED, pgmoved);
	release_pages(pvec->pages, pvec->nr, pvec->cold);
	pagevec_reinit(pvec);
}

/*
 * 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.
 *
 * Returns zero if it cleared PG_writeback.
 */
int rotate_reclaimable_page(struct page *page)
{
	struct pagevec *pvec;
	unsigned long flags;

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

	page_cache_get(page);
	local_irq_save(flags);
	pvec = &__get_cpu_var(lru_rotate_pvecs);
	if (!pagevec_add(pvec, page))
		pagevec_move_tail(pvec);
	local_irq_restore(flags);

	if (!test_clear_page_writeback(page))
		BUG();

	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
 */
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);
}

/*
 * Drain pages out of the cpu's pagevecs.
 * Either "cpu" is the current CPU, and preemption has already been
 * disabled; or "cpu" is being hot-unplugged, and is already dead.
 */
static void drain_cpu_pagevecs(int cpu)
{
	struct pagevec *pvec;

	pvec = &per_cpu(lru_add_pvecs, cpu);
	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);

	pvec = &per_cpu(lru_rotate_pvecs, cpu);
	if (pagevec_count(pvec)) {
		unsigned long flags;

		/* No harm done if a racing interrupt already did this */
		local_irq_save(flags);
		pagevec_move_tail(pvec);
		local_irq_restore(flags);
	}
}

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

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

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

#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;
	unsigned long uninitialized_var(flags);

	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_irqrestore(&zone->lru_lock, flags);
				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_irqrestore(&zone->lru_lock,
									flags);
				zone = pagezone;
				spin_lock_irqsave(&zone->lru_lock, flags);
			}
			VM_BUG_ON(!PageLRU(page));
			__ClearPageLRU(page);
			del_page_from_lru(zone, page);
		}

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

	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 || action == CPU_DEAD_FROZEN) {
		atomic_add(*committed, &vm_committed_space);
		*committed = 0;
		drain_cpu_pagevecs((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
	 */
#ifdef CONFIG_HOTPLUG_CPU
	hotcpu_notifier(cpu_swap_callback, 0);
#endif
}
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() */
1da177e4 LT	27	#include <linux/percpu_counter.h>
	28	#include <linux/percpu.h>
	29	#include <linux/cpu.h>
	30	#include <linux/notifier.h>
1da177e4 LT	31
	32	/* How many pages do we try to swap or page in/out together? */
	33	int page_cluster;
	34
902aaed0 HH	35	static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
	36	static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };
	37	static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs) = { 0, };
	38
b221385b AB	39	/*
	40	* This path almost never happens for VM activity - pages are normally
	41	* freed via pagevecs. But it gets used by networking.
	42	*/
	43	static void fastcall __page_cache_release(struct page *page)
	44	{
	45	if (PageLRU(page)) {
	46	unsigned long flags;
	47	struct zone *zone = page_zone(page);
	48
	49	spin_lock_irqsave(&zone->lru_lock, flags);
	50	VM_BUG_ON(!PageLRU(page));
	51	__ClearPageLRU(page);
	52	del_page_from_lru(zone, page);
	53	spin_unlock_irqrestore(&zone->lru_lock, flags);
	54	}
	55	free_hot_page(page);
	56	}
	57
8519fb30	58	static void put_compound_page(struct page *page)
1da177e4	59	{
d85f3385	60	page = compound_head(page);
8519fb30	61	if (put_page_testzero(page)) {
33f2ef89	62	compound_page_dtor *dtor;
1da177e4	63
33f2ef89	64	dtor = get_compound_page_dtor(page);
8519fb30	65	(*dtor)(page);
1da177e4	66	}
8519fb30 NP	67	}
	68
	69	void put_page(struct page *page)
	70	{
	71	if (unlikely(PageCompound(page)))
	72	put_compound_page(page);
	73	else if (put_page_testzero(page))
1da177e4 LT	74	__page_cache_release(page);
	75	}
	76	EXPORT_SYMBOL(put_page);
1da177e4	77
1d7ea732 AZ	78	/**
	79	* put_pages_list(): release a list of pages
	80	*
	81	* Release a list of pages which are strung together on page.lru. Currently
	82	* used by read_cache_pages() and related error recovery code.
	83	*
	84	* @pages: list of pages threaded on page->lru
	85	*/
	86	void put_pages_list(struct list_head *pages)
	87	{
	88	while (!list_empty(pages)) {
	89	struct page *victim;
	90
	91	victim = list_entry(pages->prev, struct page, lru);
	92	list_del(&victim->lru);
	93	page_cache_release(victim);
	94	}
	95	}
	96	EXPORT_SYMBOL(put_pages_list);
	97
902aaed0 HH	98	/*
	99	* pagevec_move_tail() must be called with IRQ disabled.
	100	* Otherwise this may cause nasty races.
	101	*/
	102	static void pagevec_move_tail(struct pagevec *pvec)
	103	{
	104	int i;
	105	int pgmoved = 0;
	106	struct zone *zone = NULL;
	107
	108	for (i = 0; i < pagevec_count(pvec); i++) {
	109	struct page *page = pvec->pages[i];
	110	struct zone *pagezone = page_zone(page);
	111
	112	if (pagezone != zone) {
	113	if (zone)
	114	spin_unlock(&zone->lru_lock);
	115	zone = pagezone;
	116	spin_lock(&zone->lru_lock);
	117	}
	118	if (PageLRU(page) && !PageActive(page)) {
	119	list_move_tail(&page->lru, &zone->inactive_list);
	120	pgmoved++;
	121	}
	122	}
	123	if (zone)
	124	spin_unlock(&zone->lru_lock);
	125	__count_vm_events(PGROTATED, pgmoved);
	126	release_pages(pvec->pages, pvec->nr, pvec->cold);
	127	pagevec_reinit(pvec);
	128	}
	129
1da177e4 LT	130	/*
	131	* Writeback is about to end against a page which has been marked for immediate
	132	* reclaim. If it still appears to be reclaimable, move it to the tail of the
902aaed0	133	* inactive list.
1da177e4 LT	134	*
	135	* Returns zero if it cleared PG_writeback.
	136	*/
	137	int rotate_reclaimable_page(struct page *page)
	138	{
902aaed0	139	struct pagevec *pvec;
1da177e4 LT	140	unsigned long flags;
	141
	142	if (PageLocked(page))
	143	return 1;
	144	if (PageDirty(page))
	145	return 1;
	146	if (PageActive(page))
	147	return 1;
	148	if (!PageLRU(page))
	149	return 1;
	150
902aaed0 HH	151	page_cache_get(page);
	152	local_irq_save(flags);
	153	pvec = &__get_cpu_var(lru_rotate_pvecs);
	154	if (!pagevec_add(pvec, page))
	155	pagevec_move_tail(pvec);
	156	local_irq_restore(flags);
	157
1da177e4 LT	158	if (!test_clear_page_writeback(page))
1da177e4 LT	159	BUG();
902aaed0	160
1da177e4 LT	161	return 0;
	162	}
	163
	164	/*
	165	* FIXME: speed this up?
	166	*/
	167	void fastcall activate_page(struct page *page)
	168	{
	169	struct zone *zone = page_zone(page);
	170
	171	spin_lock_irq(&zone->lru_lock);
	172	if (PageLRU(page) && !PageActive(page)) {
	173	del_page_from_inactive_list(zone, page);
	174	SetPageActive(page);
	175	add_page_to_active_list(zone, page);
f8891e5e	176	__count_vm_event(PGACTIVATE);
1da177e4 LT	177	}
	178	spin_unlock_irq(&zone->lru_lock);
	179	}
	180
	181	/*
	182	* Mark a page as having seen activity.
	183	*
	184	* inactive,unreferenced -> inactive,referenced
	185	* inactive,referenced -> active,unreferenced
	186	* active,unreferenced -> active,referenced
	187	*/
	188	void fastcall mark_page_accessed(struct page *page)
	189	{
	190	if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
	191	activate_page(page);
	192	ClearPageReferenced(page);
	193	} else if (!PageReferenced(page)) {
	194	SetPageReferenced(page);
	195	}
	196	}
	197
	198	EXPORT_SYMBOL(mark_page_accessed);
	199
	200	/**
	201	* lru_cache_add: add a page to the page lists
	202	* @page: the page to add
	203	*/
1da177e4 LT	204	void fastcall lru_cache_add(struct page *page)
	205	{
	206	struct pagevec *pvec = &get_cpu_var(lru_add_pvecs);
	207
	208	page_cache_get(page);
	209	if (!pagevec_add(pvec, page))
	210	__pagevec_lru_add(pvec);
	211	put_cpu_var(lru_add_pvecs);
	212	}
	213
	214	void fastcall lru_cache_add_active(struct page *page)
	215	{
	216	struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs);
	217
	218	page_cache_get(page);
	219	if (!pagevec_add(pvec, page))
	220	__pagevec_lru_add_active(pvec);
	221	put_cpu_var(lru_add_active_pvecs);
	222	}
	223
902aaed0 HH	224	/*
	225	* Drain pages out of the cpu's pagevecs.
	226	* Either "cpu" is the current CPU, and preemption has already been
	227	* disabled; or "cpu" is being hot-unplugged, and is already dead.
	228	*/
	229	static void drain_cpu_pagevecs(int cpu)
1da177e4	230	{
902aaed0	231	struct pagevec *pvec;
1da177e4	232
902aaed0	233	pvec = &per_cpu(lru_add_pvecs, cpu);
1da177e4 LT	234	if (pagevec_count(pvec))
1da177e4 LT	235	__pagevec_lru_add(pvec);
902aaed0	236
80bfed90	237	pvec = &per_cpu(lru_add_active_pvecs, cpu);
1da177e4 LT	238	if (pagevec_count(pvec))
1da177e4 LT	239	__pagevec_lru_add_active(pvec);
902aaed0 HH	240
	241	pvec = &per_cpu(lru_rotate_pvecs, cpu);
	242	if (pagevec_count(pvec)) {
	243	unsigned long flags;
	244
	245	/* No harm done if a racing interrupt already did this */
	246	local_irq_save(flags);
	247	pagevec_move_tail(pvec);
	248	local_irq_restore(flags);
	249	}
80bfed90 AM	250	}
	251
	252	void lru_add_drain(void)
	253	{
902aaed0	254	drain_cpu_pagevecs(get_cpu());
80bfed90	255	put_cpu();
1da177e4 LT	256	}
1da177e4 LT	257
053837fc	258	#ifdef CONFIG_NUMA
c4028958	259	static void lru_add_drain_per_cpu(struct work_struct *dummy)
053837fc NP	260	{
	261	lru_add_drain();
	262	}
	263
	264	/*
	265	* Returns 0 for success
	266	*/
	267	int lru_add_drain_all(void)
	268	{
c4028958	269	return schedule_on_each_cpu(lru_add_drain_per_cpu);
053837fc NP	270	}
	271
	272	#else
	273
	274	/*
	275	* Returns 0 for success
	276	*/
	277	int lru_add_drain_all(void)
	278	{
	279	lru_add_drain();
	280	return 0;
	281	}
	282	#endif
	283
1da177e4 LT	284	/*
	285	* Batched page_cache_release(). Decrement the reference count on all the
	286	* passed pages. If it fell to zero then remove the page from the LRU and
	287	* free it.
	288	*
	289	* Avoid taking zone->lru_lock if possible, but if it is taken, retain it
	290	* for the remainder of the operation.
	291	*
	292	* The locking in this function is against shrink_cache(): we recheck the
	293	* page count inside the lock to see whether shrink_cache grabbed the page
	294	* via the LRU. If it did, give up: shrink_cache will free it.
	295	*/
	296	void release_pages(struct page **pages, int nr, int cold)
	297	{
	298	int i;
	299	struct pagevec pages_to_free;
	300	struct zone *zone = NULL;
902aaed0	301	unsigned long uninitialized_var(flags);
1da177e4 LT	302
	303	pagevec_init(&pages_to_free, cold);
	304	for (i = 0; i < nr; i++) {
	305	struct page *page = pages[i];
1da177e4	306
8519fb30 NP	307	if (unlikely(PageCompound(page))) {
8519fb30 NP	308	if (zone) {
902aaed0	309	spin_unlock_irqrestore(&zone->lru_lock, flags);
8519fb30 NP	310	zone = NULL;
	311	}
	312	put_compound_page(page);
	313	continue;
	314	}
	315
b5810039	316	if (!put_page_testzero(page))
1da177e4 LT	317	continue;
1da177e4 LT	318
46453a6e NP	319	if (PageLRU(page)) {
	320	struct zone *pagezone = page_zone(page);
	321	if (pagezone != zone) {
	322	if (zone)
902aaed0 HH	323	spin_unlock_irqrestore(&zone->lru_lock,
902aaed0 HH	324	flags);
46453a6e	325	zone = pagezone;
902aaed0	326	spin_lock_irqsave(&zone->lru_lock, flags);
46453a6e	327	}
725d704e	328	VM_BUG_ON(!PageLRU(page));
67453911	329	__ClearPageLRU(page);
1da177e4	330	del_page_from_lru(zone, page);
46453a6e NP	331	}
	332
	333	if (!pagevec_add(&pages_to_free, page)) {
	334	if (zone) {
902aaed0	335	spin_unlock_irqrestore(&zone->lru_lock, flags);
46453a6e	336	zone = NULL;
1da177e4	337	}
46453a6e NP	338	__pagevec_free(&pages_to_free);
	339	pagevec_reinit(&pages_to_free);
	340	}
1da177e4 LT	341	}
1da177e4 LT	342	if (zone)
902aaed0	343	spin_unlock_irqrestore(&zone->lru_lock, flags);
1da177e4 LT	344
	345	pagevec_free(&pages_to_free);
	346	}
	347
	348	/*
	349	* The pages which we're about to release may be in the deferred lru-addition
	350	* queues. That would prevent them from really being freed right now. That's
	351	* OK from a correctness point of view but is inefficient - those pages may be
	352	* cache-warm and we want to give them back to the page allocator ASAP.
	353	*
	354	* So __pagevec_release() will drain those queues here. __pagevec_lru_add()
	355	* and __pagevec_lru_add_active() call release_pages() directly to avoid
	356	* mutual recursion.
	357	*/
	358	void __pagevec_release(struct pagevec *pvec)
	359	{
	360	lru_add_drain();
	361	release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
	362	pagevec_reinit(pvec);
	363	}
	364
7f285701 SF	365	EXPORT_SYMBOL(__pagevec_release);
7f285701 SF	366
1da177e4 LT	367	/*
	368	* pagevec_release() for pages which are known to not be on the LRU
	369	*
	370	* This function reinitialises the caller's pagevec.
	371	*/
	372	void __pagevec_release_nonlru(struct pagevec *pvec)
	373	{
	374	int i;
	375	struct pagevec pages_to_free;
	376
	377	pagevec_init(&pages_to_free, pvec->cold);
1da177e4 LT	378	for (i = 0; i < pagevec_count(pvec); i++) {
	379	struct page *page = pvec->pages[i];
	380
725d704e	381	VM_BUG_ON(PageLRU(page));
1da177e4 LT	382	if (put_page_testzero(page))
	383	pagevec_add(&pages_to_free, page);
	384	}
	385	pagevec_free(&pages_to_free);
	386	pagevec_reinit(pvec);
	387	}
	388
	389	/*
	390	* Add the passed pages to the LRU, then drop the caller's refcount
	391	* on them. Reinitialises the caller's pagevec.
	392	*/
	393	void __pagevec_lru_add(struct pagevec *pvec)
	394	{
	395	int i;
	396	struct zone *zone = NULL;
	397
	398	for (i = 0; i < pagevec_count(pvec); i++) {
	399	struct page *page = pvec->pages[i];
	400	struct zone *pagezone = page_zone(page);
	401
	402	if (pagezone != zone) {
	403	if (zone)
	404	spin_unlock_irq(&zone->lru_lock);
	405	zone = pagezone;
	406	spin_lock_irq(&zone->lru_lock);
	407	}
725d704e	408	VM_BUG_ON(PageLRU(page));
8d438f96	409	SetPageLRU(page);
1da177e4 LT	410	add_page_to_inactive_list(zone, page);
	411	}
	412	if (zone)
	413	spin_unlock_irq(&zone->lru_lock);
	414	release_pages(pvec->pages, pvec->nr, pvec->cold);
	415	pagevec_reinit(pvec);
	416	}
	417
	418	EXPORT_SYMBOL(__pagevec_lru_add);
	419
	420	void __pagevec_lru_add_active(struct pagevec *pvec)
	421	{
	422	int i;
	423	struct zone *zone = NULL;
	424
	425	for (i = 0; i < pagevec_count(pvec); i++) {
	426	struct page *page = pvec->pages[i];
	427	struct zone *pagezone = page_zone(page);
	428
	429	if (pagezone != zone) {
	430	if (zone)
	431	spin_unlock_irq(&zone->lru_lock);
	432	zone = pagezone;
	433	spin_lock_irq(&zone->lru_lock);
	434	}
725d704e	435	VM_BUG_ON(PageLRU(page));
8d438f96	436	SetPageLRU(page);
725d704e	437	VM_BUG_ON(PageActive(page));
4c84cacf	438	SetPageActive(page);
1da177e4 LT	439	add_page_to_active_list(zone, page);
	440	}
	441	if (zone)
	442	spin_unlock_irq(&zone->lru_lock);
	443	release_pages(pvec->pages, pvec->nr, pvec->cold);
	444	pagevec_reinit(pvec);
	445	}
	446
	447	/*
	448	* Try to drop buffers from the pages in a pagevec
	449	*/
	450	void pagevec_strip(struct pagevec *pvec)
	451	{
	452	int i;
	453
	454	for (i = 0; i < pagevec_count(pvec); i++) {
	455	struct page *page = pvec->pages[i];
	456
	457	if (PagePrivate(page) && !TestSetPageLocked(page)) {
5b40dc78 CL	458	if (PagePrivate(page))
5b40dc78 CL	459	try_to_release_page(page, 0);
1da177e4 LT	460	unlock_page(page);
	461	}
	462	}
	463	}
	464
	465	/**
	466	* pagevec_lookup - gang pagecache lookup
	467	* @pvec: Where the resulting pages are placed
	468	* @mapping: The address_space to search
	469	* @start: The starting page index
	470	* @nr_pages: The maximum number of pages
	471	*
	472	* pagevec_lookup() will search for and return a group of up to @nr_pages pages
	473	* in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
	474	* reference against the pages in @pvec.
	475	*
	476	* The search returns a group of mapping-contiguous pages with ascending
	477	* indexes. There may be holes in the indices due to not-present pages.
	478	*
	479	* pagevec_lookup() returns the number of pages which were found.
	480	*/
	481	unsigned pagevec_lookup(struct pagevec pvec, struct address_space mapping,
	482	pgoff_t start, unsigned nr_pages)
	483	{
	484	pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
	485	return pagevec_count(pvec);
	486	}
	487
78539fdf CH	488	EXPORT_SYMBOL(pagevec_lookup);
78539fdf CH	489
1da177e4 LT	490	unsigned pagevec_lookup_tag(struct pagevec pvec, struct address_space mapping,
	491	pgoff_t *index, int tag, unsigned nr_pages)
	492	{
	493	pvec->nr = find_get_pages_tag(mapping, index, tag,
	494	nr_pages, pvec->pages);
	495	return pagevec_count(pvec);
	496	}
	497
7f285701	498	EXPORT_SYMBOL(pagevec_lookup_tag);
1da177e4 LT	499
	500	#ifdef CONFIG_SMP
	501	/*
	502	* We tolerate a little inaccuracy to avoid ping-ponging the counter between
	503	* CPUs
	504	*/
	505	#define ACCT_THRESHOLD max(16, NR_CPUS * 2)
	506
	507	static DEFINE_PER_CPU(long, committed_space) = 0;
	508
	509	void vm_acct_memory(long pages)
	510	{
	511	long *local;
	512
	513	preempt_disable();
	514	local = &__get_cpu_var(committed_space);
	515	*local += pages;
	516	if (local > ACCT_THRESHOLD \|\| local < -ACCT_THRESHOLD) {
	517	atomic_add(*local, &vm_committed_space);
	518	*local = 0;
	519	}
	520	preempt_enable();
	521	}
1da177e4 LT	522
1da177e4 LT	523	#ifdef CONFIG_HOTPLUG_CPU
1da177e4 LT	524
	525	/* Drop the CPU's cached committed space back into the central pool. */
	526	static int cpu_swap_callback(struct notifier_block *nfb,
	527	unsigned long action,
	528	void *hcpu)
	529	{
	530	long *committed;
	531
	532	committed = &per_cpu(committed_space, (long)hcpu);
8bb78442	533	if (action == CPU_DEAD \|\| action == CPU_DEAD_FROZEN) {
1da177e4 LT	534	atomic_add(*committed, &vm_committed_space);
1da177e4 LT	535	*committed = 0;
902aaed0	536	drain_cpu_pagevecs((long)hcpu);
1da177e4 LT	537	}
	538	return NOTIFY_OK;
	539	}
	540	#endif /* CONFIG_HOTPLUG_CPU */
	541	#endif /* CONFIG_SMP */
	542
1da177e4 LT	543	/*
	544	* Perform any setup for the swap system
	545	*/
	546	void __init swap_setup(void)
	547	{
	548	unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);
	549
	550	/* Use a smaller cluster for small-memory machines */
	551	if (megs < 16)
	552	page_cluster = 2;
	553	else
	554	page_cluster = 3;
	555	/*
	556	* Right now other parts of the system means that we
	557	* _really_ don't want to cluster much more
	558	*/
02316067	559	#ifdef CONFIG_HOTPLUG_CPU
1da177e4	560	hotcpu_notifier(cpu_swap_callback, 0);
02316067	561	#endif
1da177e4	562	}