[linux.git] / mm / swap.c

/*
 *  linux/mm/swap.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

/*
 * This file contains the default values for the operation 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>
#include <linux/backing-dev.h>
#include <linux/memcontrol.h>

#include "internal.h"

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

static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs);
static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);

/*
 * This path almost never happens for VM activity - pages are normally
 * freed via pagevecs.  But it gets used by networking.
 */
static void __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
 * @pages: list of pages threaded on page->lru
 *
 * Release a list of pages which are strung together on page.lru.  Currently
 * used by read_cache_pages() and related error recovery code.
 */
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) && !PageUnevictable(page)) {
			int lru = page_is_file_cache(page);
			list_move_tail(&page->lru, &zone->lru[lru].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.
 */
void  rotate_reclaimable_page(struct page *page)
{
	if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
	    !PageUnevictable(page) && PageLRU(page)) {
		struct pagevec *pvec;
		unsigned long flags;

		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);
	}
}

/*
 * FIXME: speed this up?
 */
void activate_page(struct page *page)
{
	struct zone *zone = page_zone(page);

	spin_lock_irq(&zone->lru_lock);
	if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
		int file = page_is_file_cache(page);
		int lru = LRU_BASE + file;
		del_page_from_lru_list(zone, page, lru);

		SetPageActive(page);
		lru += LRU_ACTIVE;
		add_page_to_lru_list(zone, page, lru);
		__count_vm_event(PGACTIVATE);

		zone->recent_rotated[!!file]++;
		zone->recent_scanned[!!file]++;
	}
	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 mark_page_accessed(struct page *page)
{
	if (!PageActive(page) && !PageUnevictable(page) &&
			PageReferenced(page) && PageLRU(page)) {
		activate_page(page);
		ClearPageReferenced(page);
	} else if (!PageReferenced(page)) {
		SetPageReferenced(page);
	}
}

EXPORT_SYMBOL(mark_page_accessed);

void __lru_cache_add(struct page *page, enum lru_list lru)
{
	struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru];

	page_cache_get(page);
	if (!pagevec_add(pvec, page))
		____pagevec_lru_add(pvec, lru);
	put_cpu_var(lru_add_pvecs);
}

/**
 * lru_cache_add_lru - add a page to a page list
 * @page: the page to be added to the LRU.
 * @lru: the LRU list to which the page is added.
 */
void lru_cache_add_lru(struct page *page, enum lru_list lru)
{
	if (PageActive(page)) {
		VM_BUG_ON(PageUnevictable(page));
		ClearPageActive(page);
	} else if (PageUnevictable(page)) {
		VM_BUG_ON(PageActive(page));
		ClearPageUnevictable(page);
	}

	VM_BUG_ON(PageLRU(page) || PageActive(page) || PageUnevictable(page));
	__lru_cache_add(page, lru);
}

/**
 * add_page_to_unevictable_list - add a page to the unevictable list
 * @page:  the page to be added to the unevictable list
 *
 * Add page directly to its zone's unevictable list.  To avoid races with
 * tasks that might be making the page evictable, through eg. munlock,
 * munmap or exit, while it's not on the lru, we want to add the page
 * while it's locked or otherwise "invisible" to other tasks.  This is
 * difficult to do when using the pagevec cache, so bypass that.
 */
void add_page_to_unevictable_list(struct page *page)
{
	struct zone *zone = page_zone(page);

	spin_lock_irq(&zone->lru_lock);
	SetPageUnevictable(page);
	SetPageLRU(page);
	add_page_to_lru_list(zone, page, LRU_UNEVICTABLE);
	spin_unlock_irq(&zone->lru_lock);
}

/*
 * 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 *pvecs = per_cpu(lru_add_pvecs, cpu);
	struct pagevec *pvec;
	int lru;

	for_each_lru(lru) {
		pvec = &pvecs[lru - LRU_BASE];
		if (pagevec_count(pvec))
			____pagevec_lru_add(pvec, lru);
	}

	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();
}

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);
}

/*
 * 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_inactive_list(): we recheck
 * the page count inside the lock to see whether shrink_inactive_list()
 * grabbed the page via the LRU.  If it did, give up: shrink_inactive_list()
 * 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);

/*
 * 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, enum lru_list lru)
{
	int i;
	struct zone *zone = NULL;
	VM_BUG_ON(is_unevictable_lru(lru));

	for (i = 0; i < pagevec_count(pvec); i++) {
		struct page *page = pvec->pages[i];
		struct zone *pagezone = page_zone(page);
		int file;

		if (pagezone != zone) {
			if (zone)
				spin_unlock_irq(&zone->lru_lock);
			zone = pagezone;
			spin_lock_irq(&zone->lru_lock);
		}
		VM_BUG_ON(PageActive(page));
		VM_BUG_ON(PageUnevictable(page));
		VM_BUG_ON(PageLRU(page));
		SetPageLRU(page);
		file = is_file_lru(lru);
		zone->recent_scanned[file]++;
		if (is_active_lru(lru)) {
			SetPageActive(page);
			zone->recent_rotated[file]++;
		}
		add_page_to_lru_list(zone, page, lru);
	}
	if (zone)
		spin_unlock_irq(&zone->lru_lock);
	release_pages(pvec->pages, pvec->nr, pvec->cold);
	pagevec_reinit(pvec);
}

EXPORT_SYMBOL(____pagevec_lru_add);

/*
 * 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) && trylock_page(page)) {
			if (PagePrivate(page))
				try_to_release_page(page, 0);
			unlock_page(page);
		}
	}
}

/**
 * pagevec_swap_free - try to free swap space from the pages in a pagevec
 * @pvec: pagevec with swapcache pages to free the swap space of
 *
 * The caller needs to hold an extra reference to each page and
 * not hold the page lock on the pages.  This function uses a
 * trylock on the page lock so it may not always free the swap
 * space associated with a page.
 */
void pagevec_swap_free(struct pagevec *pvec)
{
	int i;

	for (i = 0; i < pagevec_count(pvec); i++) {
		struct page *page = pvec->pages[i];

		if (PageSwapCache(page) && trylock_page(page)) {
			try_to_free_swap(page);
			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);

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_long_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_long_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);

#ifdef CONFIG_SWAP
	bdi_init(swapper_space.backing_dev_info);
#endif

	/* 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	/*
183ff22b	8	* This file contains the default values for the operation of the
1da177e4 LT	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>
e0bf68dd	31	#include <linux/backing-dev.h>
66e1707b	32	#include <linux/memcontrol.h>
1da177e4	33
64d6519d LS	34	#include "internal.h"
64d6519d LS	35
1da177e4 LT	36	/* How many pages do we try to swap or page in/out together? */
	37	int page_cluster;
	38
f04e9ebb	39	static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs);
f84f9504	40	static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
902aaed0	41
b221385b AB	42	/*
	43	* This path almost never happens for VM activity - pages are normally
	44	* freed via pagevecs. But it gets used by networking.
	45	*/
920c7a5d	46	static void __page_cache_release(struct page *page)
b221385b AB	47	{
	48	if (PageLRU(page)) {
	49	unsigned long flags;
	50	struct zone *zone = page_zone(page);
	51
	52	spin_lock_irqsave(&zone->lru_lock, flags);
	53	VM_BUG_ON(!PageLRU(page));
	54	__ClearPageLRU(page);
	55	del_page_from_lru(zone, page);
	56	spin_unlock_irqrestore(&zone->lru_lock, flags);
	57	}
	58	free_hot_page(page);
	59	}
	60
8519fb30	61	static void put_compound_page(struct page *page)
1da177e4	62	{
d85f3385	63	page = compound_head(page);
8519fb30	64	if (put_page_testzero(page)) {
33f2ef89	65	compound_page_dtor *dtor;
1da177e4	66
33f2ef89	67	dtor = get_compound_page_dtor(page);
8519fb30	68	(*dtor)(page);
1da177e4	69	}
8519fb30 NP	70	}
	71
	72	void put_page(struct page *page)
	73	{
	74	if (unlikely(PageCompound(page)))
	75	put_compound_page(page);
	76	else if (put_page_testzero(page))
1da177e4 LT	77	__page_cache_release(page);
	78	}
	79	EXPORT_SYMBOL(put_page);
1da177e4	80
1d7ea732	81	/**
7682486b RD	82	* put_pages_list() - release a list of pages
7682486b RD	83	* @pages: list of pages threaded on page->lru
1d7ea732 AZ	84	*
	85	* Release a list of pages which are strung together on page.lru. Currently
	86	* used by read_cache_pages() and related error recovery code.
1d7ea732 AZ	87	*/
	88	void put_pages_list(struct list_head *pages)
	89	{
	90	while (!list_empty(pages)) {
	91	struct page *victim;
	92
	93	victim = list_entry(pages->prev, struct page, lru);
	94	list_del(&victim->lru);
	95	page_cache_release(victim);
	96	}
	97	}
	98	EXPORT_SYMBOL(put_pages_list);
	99
902aaed0 HH	100	/*
	101	* pagevec_move_tail() must be called with IRQ disabled.
	102	* Otherwise this may cause nasty races.
	103	*/
	104	static void pagevec_move_tail(struct pagevec *pvec)
	105	{
	106	int i;
	107	int pgmoved = 0;
	108	struct zone *zone = NULL;
	109
	110	for (i = 0; i < pagevec_count(pvec); i++) {
	111	struct page *page = pvec->pages[i];
	112	struct zone *pagezone = page_zone(page);
	113
	114	if (pagezone != zone) {
	115	if (zone)
	116	spin_unlock(&zone->lru_lock);
	117	zone = pagezone;
	118	spin_lock(&zone->lru_lock);
	119	}
894bc310	120	if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
4f98a2fe RR	121	int lru = page_is_file_cache(page);
4f98a2fe RR	122	list_move_tail(&page->lru, &zone->lru[lru].list);
902aaed0 HH	123	pgmoved++;
	124	}
	125	}
	126	if (zone)
	127	spin_unlock(&zone->lru_lock);
	128	__count_vm_events(PGROTATED, pgmoved);
	129	release_pages(pvec->pages, pvec->nr, pvec->cold);
	130	pagevec_reinit(pvec);
	131	}
	132
1da177e4 LT	133	/*
	134	* Writeback is about to end against a page which has been marked for immediate
	135	* reclaim. If it still appears to be reclaimable, move it to the tail of the
902aaed0	136	* inactive list.
1da177e4	137	*/
ac6aadb2	138	void rotate_reclaimable_page(struct page *page)
1da177e4	139	{
ac6aadb2	140	if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
894bc310	141	!PageUnevictable(page) && PageLRU(page)) {
ac6aadb2 MS	142	struct pagevec *pvec;
	143	unsigned long flags;
	144
	145	page_cache_get(page);
	146	local_irq_save(flags);
	147	pvec = &__get_cpu_var(lru_rotate_pvecs);
	148	if (!pagevec_add(pvec, page))
	149	pagevec_move_tail(pvec);
	150	local_irq_restore(flags);
	151	}
1da177e4 LT	152	}
	153
	154	/*
	155	* FIXME: speed this up?
	156	*/
920c7a5d	157	void activate_page(struct page *page)
1da177e4 LT	158	{
	159	struct zone *zone = page_zone(page);
	160
	161	spin_lock_irq(&zone->lru_lock);
894bc310	162	if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
4f98a2fe RR	163	int file = page_is_file_cache(page);
	164	int lru = LRU_BASE + file;
	165	del_page_from_lru_list(zone, page, lru);
	166
1da177e4	167	SetPageActive(page);
4f98a2fe RR	168	lru += LRU_ACTIVE;
4f98a2fe RR	169	add_page_to_lru_list(zone, page, lru);
f8891e5e	170	__count_vm_event(PGACTIVATE);
4f98a2fe RR	171
	172	zone->recent_rotated[!!file]++;
	173	zone->recent_scanned[!!file]++;
1da177e4 LT	174	}
	175	spin_unlock_irq(&zone->lru_lock);
	176	}
	177
	178	/*
	179	* Mark a page as having seen activity.
	180	*
	181	* inactive,unreferenced -> inactive,referenced
	182	* inactive,referenced -> active,unreferenced
	183	* active,unreferenced -> active,referenced
	184	*/
920c7a5d	185	void mark_page_accessed(struct page *page)
1da177e4	186	{
894bc310 LS	187	if (!PageActive(page) && !PageUnevictable(page) &&
894bc310 LS	188	PageReferenced(page) && PageLRU(page)) {
1da177e4 LT	189	activate_page(page);
	190	ClearPageReferenced(page);
	191	} else if (!PageReferenced(page)) {
	192	SetPageReferenced(page);
	193	}
	194	}
	195
	196	EXPORT_SYMBOL(mark_page_accessed);
	197
f04e9ebb	198	void __lru_cache_add(struct page *page, enum lru_list lru)
1da177e4	199	{
f04e9ebb	200	struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru];
1da177e4 LT	201
	202	page_cache_get(page);
	203	if (!pagevec_add(pvec, page))
f04e9ebb	204	____pagevec_lru_add(pvec, lru);
1da177e4 LT	205	put_cpu_var(lru_add_pvecs);
	206	}
	207
f04e9ebb KM	208	/**
	209	* lru_cache_add_lru - add a page to a page list
	210	* @page: the page to be added to the LRU.
	211	* @lru: the LRU list to which the page is added.
	212	*/
	213	void lru_cache_add_lru(struct page *page, enum lru_list lru)
1da177e4	214	{
f04e9ebb	215	if (PageActive(page)) {
894bc310	216	VM_BUG_ON(PageUnevictable(page));
f04e9ebb	217	ClearPageActive(page);
894bc310 LS	218	} else if (PageUnevictable(page)) {
	219	VM_BUG_ON(PageActive(page));
	220	ClearPageUnevictable(page);
f04e9ebb	221	}
1da177e4	222
894bc310	223	VM_BUG_ON(PageLRU(page) \|\| PageActive(page) \|\| PageUnevictable(page));
f04e9ebb	224	__lru_cache_add(page, lru);
1da177e4 LT	225	}
1da177e4 LT	226
894bc310 LS	227	/**
	228	* add_page_to_unevictable_list - add a page to the unevictable list
	229	* @page: the page to be added to the unevictable list
	230	*
	231	* Add page directly to its zone's unevictable list. To avoid races with
	232	* tasks that might be making the page evictable, through eg. munlock,
	233	* munmap or exit, while it's not on the lru, we want to add the page
	234	* while it's locked or otherwise "invisible" to other tasks. This is
	235	* difficult to do when using the pagevec cache, so bypass that.
	236	*/
	237	void add_page_to_unevictable_list(struct page *page)
	238	{
	239	struct zone *zone = page_zone(page);
	240
	241	spin_lock_irq(&zone->lru_lock);
	242	SetPageUnevictable(page);
	243	SetPageLRU(page);
	244	add_page_to_lru_list(zone, page, LRU_UNEVICTABLE);
	245	spin_unlock_irq(&zone->lru_lock);
	246	}
	247
902aaed0 HH	248	/*
	249	* Drain pages out of the cpu's pagevecs.
	250	* Either "cpu" is the current CPU, and preemption has already been
	251	* disabled; or "cpu" is being hot-unplugged, and is already dead.
	252	*/
	253	static void drain_cpu_pagevecs(int cpu)
1da177e4	254	{
f04e9ebb	255	struct pagevec *pvecs = per_cpu(lru_add_pvecs, cpu);
902aaed0	256	struct pagevec *pvec;
f04e9ebb	257	int lru;
1da177e4	258
f04e9ebb KM	259	for_each_lru(lru) {
	260	pvec = &pvecs[lru - LRU_BASE];
	261	if (pagevec_count(pvec))
	262	____pagevec_lru_add(pvec, lru);
	263	}
902aaed0 HH	264
	265	pvec = &per_cpu(lru_rotate_pvecs, cpu);
	266	if (pagevec_count(pvec)) {
	267	unsigned long flags;
	268
	269	/* No harm done if a racing interrupt already did this */
	270	local_irq_save(flags);
	271	pagevec_move_tail(pvec);
	272	local_irq_restore(flags);
	273	}
80bfed90 AM	274	}
	275
	276	void lru_add_drain(void)
	277	{
902aaed0	278	drain_cpu_pagevecs(get_cpu());
80bfed90	279	put_cpu();
1da177e4 LT	280	}
1da177e4 LT	281
c4028958	282	static void lru_add_drain_per_cpu(struct work_struct *dummy)
053837fc NP	283	{
	284	lru_add_drain();
	285	}
	286
	287	/*
	288	* Returns 0 for success
	289	*/
	290	int lru_add_drain_all(void)
	291	{
c4028958	292	return schedule_on_each_cpu(lru_add_drain_per_cpu);
053837fc NP	293	}
053837fc NP	294
1da177e4 LT	295	/*
	296	* Batched page_cache_release(). Decrement the reference count on all the
	297	* passed pages. If it fell to zero then remove the page from the LRU and
	298	* free it.
	299	*
	300	* Avoid taking zone->lru_lock if possible, but if it is taken, retain it
	301	* for the remainder of the operation.
	302	*
ab33dc09 FLVC	303	* The locking in this function is against shrink_inactive_list(): we recheck
	304	* the page count inside the lock to see whether shrink_inactive_list()
	305	* grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
	306	* will free it.
1da177e4 LT	307	*/
	308	void release_pages(struct page **pages, int nr, int cold)
	309	{
	310	int i;
	311	struct pagevec pages_to_free;
	312	struct zone *zone = NULL;
902aaed0	313	unsigned long uninitialized_var(flags);
1da177e4 LT	314
	315	pagevec_init(&pages_to_free, cold);
	316	for (i = 0; i < nr; i++) {
	317	struct page *page = pages[i];
1da177e4	318
8519fb30 NP	319	if (unlikely(PageCompound(page))) {
8519fb30 NP	320	if (zone) {
902aaed0	321	spin_unlock_irqrestore(&zone->lru_lock, flags);
8519fb30 NP	322	zone = NULL;
	323	}
	324	put_compound_page(page);
	325	continue;
	326	}
	327
b5810039	328	if (!put_page_testzero(page))
1da177e4 LT	329	continue;
1da177e4 LT	330
46453a6e NP	331	if (PageLRU(page)) {
46453a6e NP	332	struct zone *pagezone = page_zone(page);
894bc310	333
46453a6e NP	334	if (pagezone != zone) {
46453a6e NP	335	if (zone)
902aaed0 HH	336	spin_unlock_irqrestore(&zone->lru_lock,
902aaed0 HH	337	flags);
46453a6e	338	zone = pagezone;
902aaed0	339	spin_lock_irqsave(&zone->lru_lock, flags);
46453a6e	340	}
725d704e	341	VM_BUG_ON(!PageLRU(page));
67453911	342	__ClearPageLRU(page);
1da177e4	343	del_page_from_lru(zone, page);
46453a6e NP	344	}
	345
	346	if (!pagevec_add(&pages_to_free, page)) {
	347	if (zone) {
902aaed0	348	spin_unlock_irqrestore(&zone->lru_lock, flags);
46453a6e	349	zone = NULL;
1da177e4	350	}
46453a6e NP	351	__pagevec_free(&pages_to_free);
	352	pagevec_reinit(&pages_to_free);
	353	}
1da177e4 LT	354	}
1da177e4 LT	355	if (zone)
902aaed0	356	spin_unlock_irqrestore(&zone->lru_lock, flags);
1da177e4 LT	357
	358	pagevec_free(&pages_to_free);
	359	}
	360
	361	/*
	362	* The pages which we're about to release may be in the deferred lru-addition
	363	* queues. That would prevent them from really being freed right now. That's
	364	* OK from a correctness point of view but is inefficient - those pages may be
	365	* cache-warm and we want to give them back to the page allocator ASAP.
	366	*
	367	* So __pagevec_release() will drain those queues here. __pagevec_lru_add()
	368	* and __pagevec_lru_add_active() call release_pages() directly to avoid
	369	* mutual recursion.
	370	*/
	371	void __pagevec_release(struct pagevec *pvec)
	372	{
	373	lru_add_drain();
	374	release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
	375	pagevec_reinit(pvec);
	376	}
	377
7f285701 SF	378	EXPORT_SYMBOL(__pagevec_release);
7f285701 SF	379
1da177e4 LT	380	/*
	381	* Add the passed pages to the LRU, then drop the caller's refcount
	382	* on them. Reinitialises the caller's pagevec.
	383	*/
f04e9ebb	384	void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru)
1da177e4 LT	385	{
	386	int i;
	387	struct zone *zone = NULL;
894bc310	388	VM_BUG_ON(is_unevictable_lru(lru));
1da177e4 LT	389
	390	for (i = 0; i < pagevec_count(pvec); i++) {
	391	struct page *page = pvec->pages[i];
	392	struct zone *pagezone = page_zone(page);
9ff473b9	393	int file;
1da177e4 LT	394
	395	if (pagezone != zone) {
	396	if (zone)
	397	spin_unlock_irq(&zone->lru_lock);
	398	zone = pagezone;
	399	spin_lock_irq(&zone->lru_lock);
	400	}
894bc310 LS	401	VM_BUG_ON(PageActive(page));
894bc310 LS	402	VM_BUG_ON(PageUnevictable(page));
725d704e	403	VM_BUG_ON(PageLRU(page));
8d438f96	404	SetPageLRU(page);
9ff473b9 RR	405	file = is_file_lru(lru);
	406	zone->recent_scanned[file]++;
	407	if (is_active_lru(lru)) {
f04e9ebb	408	SetPageActive(page);
9ff473b9 RR	409	zone->recent_rotated[file]++;
9ff473b9 RR	410	}
f04e9ebb	411	add_page_to_lru_list(zone, page, lru);
1da177e4 LT	412	}
	413	if (zone)
	414	spin_unlock_irq(&zone->lru_lock);
	415	release_pages(pvec->pages, pvec->nr, pvec->cold);
	416	pagevec_reinit(pvec);
	417	}
	418
f04e9ebb	419	EXPORT_SYMBOL(____pagevec_lru_add);
1da177e4 LT	420
	421	/*
	422	* Try to drop buffers from the pages in a pagevec
	423	*/
	424	void pagevec_strip(struct pagevec *pvec)
	425	{
	426	int i;
	427
	428	for (i = 0; i < pagevec_count(pvec); i++) {
	429	struct page *page = pvec->pages[i];
	430
529ae9aa	431	if (PagePrivate(page) && trylock_page(page)) {
5b40dc78 CL	432	if (PagePrivate(page))
5b40dc78 CL	433	try_to_release_page(page, 0);
1da177e4 LT	434	unlock_page(page);
	435	}
	436	}
	437	}
	438
68a22394 RR	439	/**
	440	* pagevec_swap_free - try to free swap space from the pages in a pagevec
	441	* @pvec: pagevec with swapcache pages to free the swap space of
	442	*
	443	* The caller needs to hold an extra reference to each page and
	444	* not hold the page lock on the pages. This function uses a
	445	* trylock on the page lock so it may not always free the swap
	446	* space associated with a page.
	447	*/
	448	void pagevec_swap_free(struct pagevec *pvec)
	449	{
	450	int i;
	451
	452	for (i = 0; i < pagevec_count(pvec); i++) {
	453	struct page *page = pvec->pages[i];
	454
	455	if (PageSwapCache(page) && trylock_page(page)) {
a2c43eed	456	try_to_free_swap(page);
68a22394 RR	457	unlock_page(page);
	458	}
	459	}
	460	}
	461
1da177e4 LT	462	/**
	463	* pagevec_lookup - gang pagecache lookup
	464	* @pvec: Where the resulting pages are placed
	465	* @mapping: The address_space to search
	466	* @start: The starting page index
	467	* @nr_pages: The maximum number of pages
	468	*
	469	* pagevec_lookup() will search for and return a group of up to @nr_pages pages
	470	* in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
	471	* reference against the pages in @pvec.
	472	*
	473	* The search returns a group of mapping-contiguous pages with ascending
	474	* indexes. There may be holes in the indices due to not-present pages.
	475	*
	476	* pagevec_lookup() returns the number of pages which were found.
	477	*/
	478	unsigned pagevec_lookup(struct pagevec pvec, struct address_space mapping,
	479	pgoff_t start, unsigned nr_pages)
	480	{
	481	pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
	482	return pagevec_count(pvec);
	483	}
	484
78539fdf CH	485	EXPORT_SYMBOL(pagevec_lookup);
78539fdf CH	486
1da177e4 LT	487	unsigned pagevec_lookup_tag(struct pagevec pvec, struct address_space mapping,
	488	pgoff_t *index, int tag, unsigned nr_pages)
	489	{
	490	pvec->nr = find_get_pages_tag(mapping, index, tag,
	491	nr_pages, pvec->pages);
	492	return pagevec_count(pvec);
	493	}
	494
7f285701	495	EXPORT_SYMBOL(pagevec_lookup_tag);
1da177e4 LT	496
	497	#ifdef CONFIG_SMP
	498	/*
	499	* We tolerate a little inaccuracy to avoid ping-ponging the counter between
	500	* CPUs
	501	*/
	502	#define ACCT_THRESHOLD max(16, NR_CPUS * 2)
	503
f84f9504	504	static DEFINE_PER_CPU(long, committed_space);
1da177e4 LT	505
	506	void vm_acct_memory(long pages)
	507	{
	508	long *local;
	509
	510	preempt_disable();
	511	local = &__get_cpu_var(committed_space);
	512	*local += pages;
	513	if (local > ACCT_THRESHOLD \|\| local < -ACCT_THRESHOLD) {
80119ef5	514	atomic_long_add(*local, &vm_committed_space);
1da177e4 LT	515	*local = 0;
	516	}
	517	preempt_enable();
	518	}
1da177e4 LT	519
1da177e4 LT	520	#ifdef CONFIG_HOTPLUG_CPU
1da177e4 LT	521
	522	/* Drop the CPU's cached committed space back into the central pool. */
	523	static int cpu_swap_callback(struct notifier_block *nfb,
	524	unsigned long action,
	525	void *hcpu)
	526	{
	527	long *committed;
	528
	529	committed = &per_cpu(committed_space, (long)hcpu);
8bb78442	530	if (action == CPU_DEAD \|\| action == CPU_DEAD_FROZEN) {
80119ef5	531	atomic_long_add(*committed, &vm_committed_space);
1da177e4	532	*committed = 0;
902aaed0	533	drain_cpu_pagevecs((long)hcpu);
1da177e4 LT	534	}
	535	return NOTIFY_OK;
	536	}
	537	#endif /* CONFIG_HOTPLUG_CPU */
	538	#endif /* CONFIG_SMP */
	539
1da177e4 LT	540	/*
	541	* Perform any setup for the swap system
	542	*/
	543	void __init swap_setup(void)
	544	{
	545	unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);
	546
e0bf68dd PZ	547	#ifdef CONFIG_SWAP
	548	bdi_init(swapper_space.backing_dev_info);
	549	#endif
	550
1da177e4 LT	551	/* Use a smaller cluster for small-memory machines */
	552	if (megs < 16)
	553	page_cluster = 2;
	554	else
	555	page_cluster = 3;
	556	/*
	557	* Right now other parts of the system means that we
	558	* _really_ don't want to cluster much more
	559	*/
02316067	560	#ifdef CONFIG_HOTPLUG_CPU
1da177e4	561	hotcpu_notifier(cpu_swap_callback, 0);
02316067	562	#endif
1da177e4	563	}