[mirror_ubuntu-bionic-kernel.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;

/*
 * 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);

/*
 * 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(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;

	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 || action == CPU_DEAD_FROZEN) {
		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
	 */
#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
b221385b AB	35	/*
	36	* This path almost never happens for VM activity - pages are normally
	37	* freed via pagevecs. But it gets used by networking.
	38	*/
	39	static void fastcall __page_cache_release(struct page *page)
	40	{
	41	if (PageLRU(page)) {
	42	unsigned long flags;
	43	struct zone *zone = page_zone(page);
	44
	45	spin_lock_irqsave(&zone->lru_lock, flags);
	46	VM_BUG_ON(!PageLRU(page));
	47	__ClearPageLRU(page);
	48	del_page_from_lru(zone, page);
	49	spin_unlock_irqrestore(&zone->lru_lock, flags);
	50	}
	51	free_hot_page(page);
	52	}
	53
8519fb30	54	static void put_compound_page(struct page *page)
1da177e4	55	{
d85f3385	56	page = compound_head(page);
8519fb30	57	if (put_page_testzero(page)) {
33f2ef89	58	compound_page_dtor *dtor;
1da177e4	59
33f2ef89	60	dtor = get_compound_page_dtor(page);
8519fb30	61	(*dtor)(page);
1da177e4	62	}
8519fb30 NP	63	}
	64
	65	void put_page(struct page *page)
	66	{
	67	if (unlikely(PageCompound(page)))
	68	put_compound_page(page);
	69	else if (put_page_testzero(page))
1da177e4 LT	70	__page_cache_release(page);
	71	}
	72	EXPORT_SYMBOL(put_page);
1da177e4	73
1d7ea732 AZ	74	/**
	75	* put_pages_list(): release a list of pages
	76	*
	77	* Release a list of pages which are strung together on page.lru. Currently
	78	* used by read_cache_pages() and related error recovery code.
	79	*
	80	* @pages: list of pages threaded on page->lru
	81	*/
	82	void put_pages_list(struct list_head *pages)
	83	{
	84	while (!list_empty(pages)) {
	85	struct page *victim;
	86
	87	victim = list_entry(pages->prev, struct page, lru);
	88	list_del(&victim->lru);
	89	page_cache_release(victim);
	90	}
	91	}
	92	EXPORT_SYMBOL(put_pages_list);
	93
1da177e4 LT	94	/*
	95	* Writeback is about to end against a page which has been marked for immediate
	96	* reclaim. If it still appears to be reclaimable, move it to the tail of the
	97	* inactive list. The page still has PageWriteback set, which will pin it.
	98	*
	99	* We don't expect many pages to come through here, so don't bother batching
	100	* things up.
	101	*
	102	* To avoid placing the page at the tail of the LRU while PG_writeback is still
	103	* set, this function will clear PG_writeback before performing the page
	104	* motion. Do that inside the lru lock because once PG_writeback is cleared
	105	* we may not touch the page.
	106	*
	107	* Returns zero if it cleared PG_writeback.
	108	*/
	109	int rotate_reclaimable_page(struct page *page)
	110	{
	111	struct zone *zone;
	112	unsigned long flags;
	113
	114	if (PageLocked(page))
	115	return 1;
	116	if (PageDirty(page))
	117	return 1;
	118	if (PageActive(page))
	119	return 1;
	120	if (!PageLRU(page))
	121	return 1;
	122
	123	zone = page_zone(page);
	124	spin_lock_irqsave(&zone->lru_lock, flags);
	125	if (PageLRU(page) && !PageActive(page)) {
1bfba4e8	126	list_move_tail(&page->lru, &zone->inactive_list);
f8891e5e	127	__count_vm_event(PGROTATED);
1da177e4 LT	128	}
	129	if (!test_clear_page_writeback(page))
	130	BUG();
	131	spin_unlock_irqrestore(&zone->lru_lock, flags);
	132	return 0;
	133	}
	134
	135	/*
	136	* FIXME: speed this up?
	137	*/
	138	void fastcall activate_page(struct page *page)
	139	{
	140	struct zone *zone = page_zone(page);
	141
	142	spin_lock_irq(&zone->lru_lock);
	143	if (PageLRU(page) && !PageActive(page)) {
	144	del_page_from_inactive_list(zone, page);
	145	SetPageActive(page);
	146	add_page_to_active_list(zone, page);
f8891e5e	147	__count_vm_event(PGACTIVATE);
1da177e4 LT	148	}
	149	spin_unlock_irq(&zone->lru_lock);
	150	}
	151
	152	/*
	153	* Mark a page as having seen activity.
	154	*
	155	* inactive,unreferenced -> inactive,referenced
	156	* inactive,referenced -> active,unreferenced
	157	* active,unreferenced -> active,referenced
	158	*/
	159	void fastcall mark_page_accessed(struct page *page)
	160	{
	161	if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
	162	activate_page(page);
	163	ClearPageReferenced(page);
	164	} else if (!PageReferenced(page)) {
	165	SetPageReferenced(page);
	166	}
	167	}
	168
	169	EXPORT_SYMBOL(mark_page_accessed);
	170
	171	/**
	172	* lru_cache_add: add a page to the page lists
	173	* @page: the page to add
	174	*/
	175	static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
	176	static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };
	177
	178	void fastcall lru_cache_add(struct page *page)
	179	{
	180	struct pagevec *pvec = &get_cpu_var(lru_add_pvecs);
	181
	182	page_cache_get(page);
	183	if (!pagevec_add(pvec, page))
	184	__pagevec_lru_add(pvec);
	185	put_cpu_var(lru_add_pvecs);
	186	}
	187
	188	void fastcall lru_cache_add_active(struct page *page)
	189	{
	190	struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs);
	191
	192	page_cache_get(page);
	193	if (!pagevec_add(pvec, page))
	194	__pagevec_lru_add_active(pvec);
	195	put_cpu_var(lru_add_active_pvecs);
	196	}
	197
80bfed90	198	static void __lru_add_drain(int cpu)
1da177e4	199	{
80bfed90	200	struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu);
1da177e4	201
80bfed90	202	/* CPU is dead, so no locking needed. */
1da177e4 LT	203	if (pagevec_count(pvec))
1da177e4 LT	204	__pagevec_lru_add(pvec);
80bfed90	205	pvec = &per_cpu(lru_add_active_pvecs, cpu);
1da177e4 LT	206	if (pagevec_count(pvec))
1da177e4 LT	207	__pagevec_lru_add_active(pvec);
80bfed90 AM	208	}
	209
	210	void lru_add_drain(void)
	211	{
	212	__lru_add_drain(get_cpu());
	213	put_cpu();
1da177e4 LT	214	}
1da177e4 LT	215
053837fc	216	#ifdef CONFIG_NUMA
c4028958	217	static void lru_add_drain_per_cpu(struct work_struct *dummy)
053837fc NP	218	{
	219	lru_add_drain();
	220	}
	221
	222	/*
	223	* Returns 0 for success
	224	*/
	225	int lru_add_drain_all(void)
	226	{
c4028958	227	return schedule_on_each_cpu(lru_add_drain_per_cpu);
053837fc NP	228	}
	229
	230	#else
	231
	232	/*
	233	* Returns 0 for success
	234	*/
	235	int lru_add_drain_all(void)
	236	{
	237	lru_add_drain();
	238	return 0;
	239	}
	240	#endif
	241
1da177e4 LT	242	/*
	243	* Batched page_cache_release(). Decrement the reference count on all the
	244	* passed pages. If it fell to zero then remove the page from the LRU and
	245	* free it.
	246	*
	247	* Avoid taking zone->lru_lock if possible, but if it is taken, retain it
	248	* for the remainder of the operation.
	249	*
	250	* The locking in this function is against shrink_cache(): we recheck the
	251	* page count inside the lock to see whether shrink_cache grabbed the page
	252	* via the LRU. If it did, give up: shrink_cache will free it.
	253	*/
	254	void release_pages(struct page **pages, int nr, int cold)
	255	{
	256	int i;
	257	struct pagevec pages_to_free;
	258	struct zone *zone = NULL;
	259
	260	pagevec_init(&pages_to_free, cold);
	261	for (i = 0; i < nr; i++) {
	262	struct page *page = pages[i];
1da177e4	263
8519fb30 NP	264	if (unlikely(PageCompound(page))) {
	265	if (zone) {
	266	spin_unlock_irq(&zone->lru_lock);
	267	zone = NULL;
	268	}
	269	put_compound_page(page);
	270	continue;
	271	}
	272
b5810039	273	if (!put_page_testzero(page))
1da177e4 LT	274	continue;
1da177e4 LT	275
46453a6e NP	276	if (PageLRU(page)) {
	277	struct zone *pagezone = page_zone(page);
	278	if (pagezone != zone) {
	279	if (zone)
	280	spin_unlock_irq(&zone->lru_lock);
	281	zone = pagezone;
	282	spin_lock_irq(&zone->lru_lock);
	283	}
725d704e	284	VM_BUG_ON(!PageLRU(page));
67453911	285	__ClearPageLRU(page);
1da177e4	286	del_page_from_lru(zone, page);
46453a6e NP	287	}
	288
	289	if (!pagevec_add(&pages_to_free, page)) {
	290	if (zone) {
1da177e4	291	spin_unlock_irq(&zone->lru_lock);
46453a6e	292	zone = NULL;
1da177e4	293	}
46453a6e NP	294	__pagevec_free(&pages_to_free);
	295	pagevec_reinit(&pages_to_free);
	296	}
1da177e4 LT	297	}
	298	if (zone)
	299	spin_unlock_irq(&zone->lru_lock);
	300
	301	pagevec_free(&pages_to_free);
	302	}
	303
	304	/*
	305	* The pages which we're about to release may be in the deferred lru-addition
	306	* queues. That would prevent them from really being freed right now. That's
	307	* OK from a correctness point of view but is inefficient - those pages may be
	308	* cache-warm and we want to give them back to the page allocator ASAP.
	309	*
	310	* So __pagevec_release() will drain those queues here. __pagevec_lru_add()
	311	* and __pagevec_lru_add_active() call release_pages() directly to avoid
	312	* mutual recursion.
	313	*/
	314	void __pagevec_release(struct pagevec *pvec)
	315	{
	316	lru_add_drain();
	317	release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
	318	pagevec_reinit(pvec);
	319	}
	320
7f285701 SF	321	EXPORT_SYMBOL(__pagevec_release);
7f285701 SF	322
1da177e4 LT	323	/*
	324	* pagevec_release() for pages which are known to not be on the LRU
	325	*
	326	* This function reinitialises the caller's pagevec.
	327	*/
	328	void __pagevec_release_nonlru(struct pagevec *pvec)
	329	{
	330	int i;
	331	struct pagevec pages_to_free;
	332
	333	pagevec_init(&pages_to_free, pvec->cold);
1da177e4 LT	334	for (i = 0; i < pagevec_count(pvec); i++) {
	335	struct page *page = pvec->pages[i];
	336
725d704e	337	VM_BUG_ON(PageLRU(page));
1da177e4 LT	338	if (put_page_testzero(page))
	339	pagevec_add(&pages_to_free, page);
	340	}
	341	pagevec_free(&pages_to_free);
	342	pagevec_reinit(pvec);
	343	}
	344
	345	/*
	346	* Add the passed pages to the LRU, then drop the caller's refcount
	347	* on them. Reinitialises the caller's pagevec.
	348	*/
	349	void __pagevec_lru_add(struct pagevec *pvec)
	350	{
	351	int i;
	352	struct zone *zone = NULL;
	353
	354	for (i = 0; i < pagevec_count(pvec); i++) {
	355	struct page *page = pvec->pages[i];
	356	struct zone *pagezone = page_zone(page);
	357
	358	if (pagezone != zone) {
	359	if (zone)
	360	spin_unlock_irq(&zone->lru_lock);
	361	zone = pagezone;
	362	spin_lock_irq(&zone->lru_lock);
	363	}
725d704e	364	VM_BUG_ON(PageLRU(page));
8d438f96	365	SetPageLRU(page);
1da177e4 LT	366	add_page_to_inactive_list(zone, page);
	367	}
	368	if (zone)
	369	spin_unlock_irq(&zone->lru_lock);
	370	release_pages(pvec->pages, pvec->nr, pvec->cold);
	371	pagevec_reinit(pvec);
	372	}
	373
	374	EXPORT_SYMBOL(__pagevec_lru_add);
	375
	376	void __pagevec_lru_add_active(struct pagevec *pvec)
	377	{
	378	int i;
	379	struct zone *zone = NULL;
	380
	381	for (i = 0; i < pagevec_count(pvec); i++) {
	382	struct page *page = pvec->pages[i];
	383	struct zone *pagezone = page_zone(page);
	384
	385	if (pagezone != zone) {
	386	if (zone)
	387	spin_unlock_irq(&zone->lru_lock);
	388	zone = pagezone;
	389	spin_lock_irq(&zone->lru_lock);
	390	}
725d704e	391	VM_BUG_ON(PageLRU(page));
8d438f96	392	SetPageLRU(page);
725d704e	393	VM_BUG_ON(PageActive(page));
4c84cacf	394	SetPageActive(page);
1da177e4 LT	395	add_page_to_active_list(zone, page);
	396	}
	397	if (zone)
	398	spin_unlock_irq(&zone->lru_lock);
	399	release_pages(pvec->pages, pvec->nr, pvec->cold);
	400	pagevec_reinit(pvec);
	401	}
	402
	403	/*
	404	* Try to drop buffers from the pages in a pagevec
	405	*/
	406	void pagevec_strip(struct pagevec *pvec)
	407	{
	408	int i;
	409
	410	for (i = 0; i < pagevec_count(pvec); i++) {
	411	struct page *page = pvec->pages[i];
	412
	413	if (PagePrivate(page) && !TestSetPageLocked(page)) {
5b40dc78 CL	414	if (PagePrivate(page))
5b40dc78 CL	415	try_to_release_page(page, 0);
1da177e4 LT	416	unlock_page(page);
	417	}
	418	}
	419	}
	420
	421	/**
	422	* pagevec_lookup - gang pagecache lookup
	423	* @pvec: Where the resulting pages are placed
	424	* @mapping: The address_space to search
	425	* @start: The starting page index
	426	* @nr_pages: The maximum number of pages
	427	*
	428	* pagevec_lookup() will search for and return a group of up to @nr_pages pages
	429	* in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
	430	* reference against the pages in @pvec.
	431	*
	432	* The search returns a group of mapping-contiguous pages with ascending
	433	* indexes. There may be holes in the indices due to not-present pages.
	434	*
	435	* pagevec_lookup() returns the number of pages which were found.
	436	*/
	437	unsigned pagevec_lookup(struct pagevec pvec, struct address_space mapping,
	438	pgoff_t start, unsigned nr_pages)
	439	{
	440	pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
	441	return pagevec_count(pvec);
	442	}
	443
78539fdf CH	444	EXPORT_SYMBOL(pagevec_lookup);
78539fdf CH	445
1da177e4 LT	446	unsigned pagevec_lookup_tag(struct pagevec pvec, struct address_space mapping,
	447	pgoff_t *index, int tag, unsigned nr_pages)
	448	{
	449	pvec->nr = find_get_pages_tag(mapping, index, tag,
	450	nr_pages, pvec->pages);
	451	return pagevec_count(pvec);
	452	}
	453
7f285701	454	EXPORT_SYMBOL(pagevec_lookup_tag);
1da177e4 LT	455
	456	#ifdef CONFIG_SMP
	457	/*
	458	* We tolerate a little inaccuracy to avoid ping-ponging the counter between
	459	* CPUs
	460	*/
	461	#define ACCT_THRESHOLD max(16, NR_CPUS * 2)
	462
	463	static DEFINE_PER_CPU(long, committed_space) = 0;
	464
	465	void vm_acct_memory(long pages)
	466	{
	467	long *local;
	468
	469	preempt_disable();
	470	local = &__get_cpu_var(committed_space);
	471	*local += pages;
	472	if (local > ACCT_THRESHOLD \|\| local < -ACCT_THRESHOLD) {
	473	atomic_add(*local, &vm_committed_space);
	474	*local = 0;
	475	}
	476	preempt_enable();
	477	}
1da177e4 LT	478
1da177e4 LT	479	#ifdef CONFIG_HOTPLUG_CPU
1da177e4 LT	480
	481	/* Drop the CPU's cached committed space back into the central pool. */
	482	static int cpu_swap_callback(struct notifier_block *nfb,
	483	unsigned long action,
	484	void *hcpu)
	485	{
	486	long *committed;
	487
	488	committed = &per_cpu(committed_space, (long)hcpu);
8bb78442	489	if (action == CPU_DEAD \|\| action == CPU_DEAD_FROZEN) {
1da177e4 LT	490	atomic_add(*committed, &vm_committed_space);
1da177e4 LT	491	*committed = 0;
80bfed90	492	__lru_add_drain((long)hcpu);
1da177e4 LT	493	}
	494	return NOTIFY_OK;
	495	}
	496	#endif /* CONFIG_HOTPLUG_CPU */
	497	#endif /* CONFIG_SMP */
	498
1da177e4 LT	499	/*
	500	* Perform any setup for the swap system
	501	*/
	502	void __init swap_setup(void)
	503	{
	504	unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);
	505
	506	/* Use a smaller cluster for small-memory machines */
	507	if (megs < 16)
	508	page_cluster = 2;
	509	else
	510	page_cluster = 3;
	511	/*
	512	* Right now other parts of the system means that we
	513	* _really_ don't want to cluster much more
	514	*/
02316067	515	#ifdef CONFIG_HOTPLUG_CPU
1da177e4	516	hotcpu_notifier(cpu_swap_callback, 0);
02316067	517	#endif
1da177e4	518	}