[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_lru_base_type(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);
	}
}

static void update_page_reclaim_stat(struct zone *zone, struct page *page,
				     int file, int rotated)
{
	struct zone_reclaim_stat *reclaim_stat = &zone->reclaim_stat;
	struct zone_reclaim_stat *memcg_reclaim_stat;

	memcg_reclaim_stat = mem_cgroup_get_reclaim_stat_from_page(page);

	reclaim_stat->recent_scanned[file]++;
	if (rotated)
		reclaim_stat->recent_rotated[file]++;

	if (!memcg_reclaim_stat)
		return;

	memcg_reclaim_stat->recent_scanned[file]++;
	if (rotated)
		memcg_reclaim_stat->recent_rotated[file]++;
}

/*
 * 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 = page_lru_base_type(page);
		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);

		update_page_reclaim_stat(zone, page, file, 1);
	}
	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;
		int active;

		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);
		active = is_active_lru(lru);
		file = is_file_lru(lru);
		if (active)
			SetPageActive(page);
		update_page_reclaim_stat(zone, page, file, active);
		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 (page_has_private(page) && trylock_page(page)) {
			if (page_has_private(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);

/*
 * Perform any setup for the swap system
 */
void __init swap_setup(void)
{
	unsigned long megs = totalram_pages >> (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
	 */
}
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)) {
401a8e1c	121	int lru = page_lru_base_type(page);
4f98a2fe	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	}
1da177e4 LT	153
3e2f41f1 KM	154	static void update_page_reclaim_stat(struct zone zone, struct page page,
	155	int file, int rotated)
	156	{
	157	struct zone_reclaim_stat *reclaim_stat = &zone->reclaim_stat;
	158	struct zone_reclaim_stat *memcg_reclaim_stat;
	159
	160	memcg_reclaim_stat = mem_cgroup_get_reclaim_stat_from_page(page);
	161
	162	reclaim_stat->recent_scanned[file]++;
	163	if (rotated)
	164	reclaim_stat->recent_rotated[file]++;
	165
	166	if (!memcg_reclaim_stat)
	167	return;
	168
	169	memcg_reclaim_stat->recent_scanned[file]++;
	170	if (rotated)
	171	memcg_reclaim_stat->recent_rotated[file]++;
	172	}
	173
1da177e4 LT	174	/*
	175	* FIXME: speed this up?
	176	*/
920c7a5d	177	void activate_page(struct page *page)
1da177e4 LT	178	{
	179	struct zone *zone = page_zone(page);
	180
	181	spin_lock_irq(&zone->lru_lock);
894bc310	182	if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
4f98a2fe	183	int file = page_is_file_cache(page);
401a8e1c	184	int lru = page_lru_base_type(page);
4f98a2fe RR	185	del_page_from_lru_list(zone, page, lru);
4f98a2fe RR	186
1da177e4	187	SetPageActive(page);
4f98a2fe RR	188	lru += LRU_ACTIVE;
4f98a2fe RR	189	add_page_to_lru_list(zone, page, lru);
f8891e5e	190	__count_vm_event(PGACTIVATE);
4f98a2fe	191
6c0b1351	192	update_page_reclaim_stat(zone, page, file, 1);
1da177e4 LT	193	}
	194	spin_unlock_irq(&zone->lru_lock);
	195	}
	196
	197	/*
	198	* Mark a page as having seen activity.
	199	*
	200	* inactive,unreferenced -> inactive,referenced
	201	* inactive,referenced -> active,unreferenced
	202	* active,unreferenced -> active,referenced
	203	*/
920c7a5d	204	void mark_page_accessed(struct page *page)
1da177e4	205	{
894bc310 LS	206	if (!PageActive(page) && !PageUnevictable(page) &&
894bc310 LS	207	PageReferenced(page) && PageLRU(page)) {
1da177e4 LT	208	activate_page(page);
	209	ClearPageReferenced(page);
	210	} else if (!PageReferenced(page)) {
	211	SetPageReferenced(page);
	212	}
	213	}
	214
	215	EXPORT_SYMBOL(mark_page_accessed);
	216
f04e9ebb	217	void __lru_cache_add(struct page *page, enum lru_list lru)
1da177e4	218	{
f04e9ebb	219	struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru];
1da177e4 LT	220
	221	page_cache_get(page);
	222	if (!pagevec_add(pvec, page))
f04e9ebb	223	____pagevec_lru_add(pvec, lru);
1da177e4 LT	224	put_cpu_var(lru_add_pvecs);
	225	}
	226
f04e9ebb KM	227	/**
	228	* lru_cache_add_lru - add a page to a page list
	229	* @page: the page to be added to the LRU.
	230	* @lru: the LRU list to which the page is added.
	231	*/
	232	void lru_cache_add_lru(struct page *page, enum lru_list lru)
1da177e4	233	{
f04e9ebb	234	if (PageActive(page)) {
894bc310	235	VM_BUG_ON(PageUnevictable(page));
f04e9ebb	236	ClearPageActive(page);
894bc310 LS	237	} else if (PageUnevictable(page)) {
	238	VM_BUG_ON(PageActive(page));
	239	ClearPageUnevictable(page);
f04e9ebb	240	}
1da177e4	241
894bc310	242	VM_BUG_ON(PageLRU(page) \|\| PageActive(page) \|\| PageUnevictable(page));
f04e9ebb	243	__lru_cache_add(page, lru);
1da177e4 LT	244	}
1da177e4 LT	245
894bc310 LS	246	/**
	247	* add_page_to_unevictable_list - add a page to the unevictable list
	248	* @page: the page to be added to the unevictable list
	249	*
	250	* Add page directly to its zone's unevictable list. To avoid races with
	251	* tasks that might be making the page evictable, through eg. munlock,
	252	* munmap or exit, while it's not on the lru, we want to add the page
	253	* while it's locked or otherwise "invisible" to other tasks. This is
	254	* difficult to do when using the pagevec cache, so bypass that.
	255	*/
	256	void add_page_to_unevictable_list(struct page *page)
	257	{
	258	struct zone *zone = page_zone(page);
	259
	260	spin_lock_irq(&zone->lru_lock);
	261	SetPageUnevictable(page);
	262	SetPageLRU(page);
	263	add_page_to_lru_list(zone, page, LRU_UNEVICTABLE);
	264	spin_unlock_irq(&zone->lru_lock);
	265	}
	266
902aaed0 HH	267	/*
	268	* Drain pages out of the cpu's pagevecs.
	269	* Either "cpu" is the current CPU, and preemption has already been
	270	* disabled; or "cpu" is being hot-unplugged, and is already dead.
	271	*/
	272	static void drain_cpu_pagevecs(int cpu)
1da177e4	273	{
f04e9ebb	274	struct pagevec *pvecs = per_cpu(lru_add_pvecs, cpu);
902aaed0	275	struct pagevec *pvec;
f04e9ebb	276	int lru;
1da177e4	277
f04e9ebb KM	278	for_each_lru(lru) {
	279	pvec = &pvecs[lru - LRU_BASE];
	280	if (pagevec_count(pvec))
	281	____pagevec_lru_add(pvec, lru);
	282	}
902aaed0 HH	283
	284	pvec = &per_cpu(lru_rotate_pvecs, cpu);
	285	if (pagevec_count(pvec)) {
	286	unsigned long flags;
	287
	288	/* No harm done if a racing interrupt already did this */
	289	local_irq_save(flags);
	290	pagevec_move_tail(pvec);
	291	local_irq_restore(flags);
	292	}
80bfed90 AM	293	}
	294
	295	void lru_add_drain(void)
	296	{
902aaed0	297	drain_cpu_pagevecs(get_cpu());
80bfed90	298	put_cpu();
1da177e4 LT	299	}
1da177e4 LT	300
c4028958	301	static void lru_add_drain_per_cpu(struct work_struct *dummy)
053837fc NP	302	{
	303	lru_add_drain();
	304	}
	305
	306	/*
	307	* Returns 0 for success
	308	*/
	309	int lru_add_drain_all(void)
	310	{
c4028958	311	return schedule_on_each_cpu(lru_add_drain_per_cpu);
053837fc NP	312	}
053837fc NP	313
1da177e4 LT	314	/*
	315	* Batched page_cache_release(). Decrement the reference count on all the
	316	* passed pages. If it fell to zero then remove the page from the LRU and
	317	* free it.
	318	*
	319	* Avoid taking zone->lru_lock if possible, but if it is taken, retain it
	320	* for the remainder of the operation.
	321	*
ab33dc09 FLVC	322	* The locking in this function is against shrink_inactive_list(): we recheck
	323	* the page count inside the lock to see whether shrink_inactive_list()
	324	* grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
	325	* will free it.
1da177e4 LT	326	*/
	327	void release_pages(struct page **pages, int nr, int cold)
	328	{
	329	int i;
	330	struct pagevec pages_to_free;
	331	struct zone *zone = NULL;
902aaed0	332	unsigned long uninitialized_var(flags);
1da177e4 LT	333
	334	pagevec_init(&pages_to_free, cold);
	335	for (i = 0; i < nr; i++) {
	336	struct page *page = pages[i];
1da177e4	337
8519fb30 NP	338	if (unlikely(PageCompound(page))) {
8519fb30 NP	339	if (zone) {
902aaed0	340	spin_unlock_irqrestore(&zone->lru_lock, flags);
8519fb30 NP	341	zone = NULL;
	342	}
	343	put_compound_page(page);
	344	continue;
	345	}
	346
b5810039	347	if (!put_page_testzero(page))
1da177e4 LT	348	continue;
1da177e4 LT	349
46453a6e NP	350	if (PageLRU(page)) {
46453a6e NP	351	struct zone *pagezone = page_zone(page);
894bc310	352
46453a6e NP	353	if (pagezone != zone) {
46453a6e NP	354	if (zone)
902aaed0 HH	355	spin_unlock_irqrestore(&zone->lru_lock,
902aaed0 HH	356	flags);
46453a6e	357	zone = pagezone;
902aaed0	358	spin_lock_irqsave(&zone->lru_lock, flags);
46453a6e	359	}
725d704e	360	VM_BUG_ON(!PageLRU(page));
67453911	361	__ClearPageLRU(page);
1da177e4	362	del_page_from_lru(zone, page);
46453a6e NP	363	}
	364
	365	if (!pagevec_add(&pages_to_free, page)) {
	366	if (zone) {
902aaed0	367	spin_unlock_irqrestore(&zone->lru_lock, flags);
46453a6e	368	zone = NULL;
1da177e4	369	}
46453a6e NP	370	__pagevec_free(&pages_to_free);
	371	pagevec_reinit(&pages_to_free);
	372	}
1da177e4 LT	373	}
1da177e4 LT	374	if (zone)
902aaed0	375	spin_unlock_irqrestore(&zone->lru_lock, flags);
1da177e4 LT	376
	377	pagevec_free(&pages_to_free);
	378	}
	379
	380	/*
	381	* The pages which we're about to release may be in the deferred lru-addition
	382	* queues. That would prevent them from really being freed right now. That's
	383	* OK from a correctness point of view but is inefficient - those pages may be
	384	* cache-warm and we want to give them back to the page allocator ASAP.
	385	*
	386	* So __pagevec_release() will drain those queues here. __pagevec_lru_add()
	387	* and __pagevec_lru_add_active() call release_pages() directly to avoid
	388	* mutual recursion.
	389	*/
	390	void __pagevec_release(struct pagevec *pvec)
	391	{
	392	lru_add_drain();
	393	release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
	394	pagevec_reinit(pvec);
	395	}
	396
7f285701 SF	397	EXPORT_SYMBOL(__pagevec_release);
7f285701 SF	398
1da177e4 LT	399	/*
	400	* Add the passed pages to the LRU, then drop the caller's refcount
	401	* on them. Reinitialises the caller's pagevec.
	402	*/
f04e9ebb	403	void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru)
1da177e4 LT	404	{
	405	int i;
	406	struct zone *zone = NULL;
6e901571	407
894bc310	408	VM_BUG_ON(is_unevictable_lru(lru));
1da177e4 LT	409
	410	for (i = 0; i < pagevec_count(pvec); i++) {
	411	struct page *page = pvec->pages[i];
	412	struct zone *pagezone = page_zone(page);
9ff473b9	413	int file;
3e2f41f1	414	int active;
1da177e4 LT	415
	416	if (pagezone != zone) {
	417	if (zone)
	418	spin_unlock_irq(&zone->lru_lock);
	419	zone = pagezone;
	420	spin_lock_irq(&zone->lru_lock);
	421	}
894bc310 LS	422	VM_BUG_ON(PageActive(page));
894bc310 LS	423	VM_BUG_ON(PageUnevictable(page));
725d704e	424	VM_BUG_ON(PageLRU(page));
8d438f96	425	SetPageLRU(page);
3e2f41f1	426	active = is_active_lru(lru);
9ff473b9	427	file = is_file_lru(lru);
3e2f41f1	428	if (active)
f04e9ebb	429	SetPageActive(page);
3e2f41f1	430	update_page_reclaim_stat(zone, page, file, active);
f04e9ebb	431	add_page_to_lru_list(zone, page, lru);
1da177e4 LT	432	}
	433	if (zone)
	434	spin_unlock_irq(&zone->lru_lock);
	435	release_pages(pvec->pages, pvec->nr, pvec->cold);
	436	pagevec_reinit(pvec);
	437	}
	438
f04e9ebb	439	EXPORT_SYMBOL(____pagevec_lru_add);
1da177e4 LT	440
	441	/*
	442	* Try to drop buffers from the pages in a pagevec
	443	*/
	444	void pagevec_strip(struct pagevec *pvec)
	445	{
	446	int i;
	447
	448	for (i = 0; i < pagevec_count(pvec); i++) {
	449	struct page *page = pvec->pages[i];
	450
266cf658 DH	451	if (page_has_private(page) && trylock_page(page)) {
266cf658 DH	452	if (page_has_private(page))
5b40dc78	453	try_to_release_page(page, 0);
1da177e4 LT	454	unlock_page(page);
	455	}
	456	}
	457	}
	458
	459	/**
	460	* pagevec_lookup - gang pagecache lookup
	461	* @pvec: Where the resulting pages are placed
	462	* @mapping: The address_space to search
	463	* @start: The starting page index
	464	* @nr_pages: The maximum number of pages
	465	*
	466	* pagevec_lookup() will search for and return a group of up to @nr_pages pages
	467	* in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
	468	* reference against the pages in @pvec.
	469	*
	470	* The search returns a group of mapping-contiguous pages with ascending
	471	* indexes. There may be holes in the indices due to not-present pages.
	472	*
	473	* pagevec_lookup() returns the number of pages which were found.
	474	*/
	475	unsigned pagevec_lookup(struct pagevec pvec, struct address_space mapping,
	476	pgoff_t start, unsigned nr_pages)
	477	{
	478	pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
	479	return pagevec_count(pvec);
	480	}
	481
78539fdf CH	482	EXPORT_SYMBOL(pagevec_lookup);
78539fdf CH	483
1da177e4 LT	484	unsigned pagevec_lookup_tag(struct pagevec pvec, struct address_space mapping,
	485	pgoff_t *index, int tag, unsigned nr_pages)
	486	{
	487	pvec->nr = find_get_pages_tag(mapping, index, tag,
	488	nr_pages, pvec->pages);
	489	return pagevec_count(pvec);
	490	}
	491
7f285701	492	EXPORT_SYMBOL(pagevec_lookup_tag);
1da177e4	493
1da177e4 LT	494	/*
	495	* Perform any setup for the swap system
	496	*/
	497	void __init swap_setup(void)
	498	{
4481374c	499	unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
1da177e4	500
e0bf68dd PZ	501	#ifdef CONFIG_SWAP
	502	bdi_init(swapper_space.backing_dev_info);
	503	#endif
	504
1da177e4 LT	505	/* Use a smaller cluster for small-memory machines */
	506	if (megs < 16)
	507	page_cluster = 2;
	508	else
	509	page_cluster = 3;
	510	/*
	511	* Right now other parts of the system means that we
	512	* _really_ don't want to cluster much more
	513	*/
1da177e4	514	}