1/* Modified by Broadcom Corp. Portions Copyright (c) Broadcom Corp, 2012. */
2/*
3 *  linux/mm/swap.c
4 *
5 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
6 */
7
8/*
9 * This file contains the default values for the operation of the
10 * Linux VM subsystem. Fine-tuning documentation can be found in
11 * Documentation/sysctl/vm.txt.
12 * Started 18.12.91
13 * Swap aging added 23.2.95, Stephen Tweedie.
14 * Buffermem limits added 12.3.98, Rik van Riel.
15 */
16
17#include <linux/mm.h>
18#include <linux/sched.h>
19#include <linux/kernel_stat.h>
20#include <linux/swap.h>
21#include <linux/mman.h>
22#include <linux/pagemap.h>
23#include <linux/pagevec.h>
24#include <linux/init.h>
25#include <linux/module.h>
26#include <linux/mm_inline.h>
27#include <linux/buffer_head.h>	/* for try_to_release_page() */
28#include <linux/percpu_counter.h>
29#include <linux/percpu.h>
30#include <linux/cpu.h>
31#include <linux/notifier.h>
32#include <linux/backing-dev.h>
33#include <linux/memcontrol.h>
34#include <linux/gfp.h>
35
36#include "internal.h"
37
38#include <typedefs.h>
39#include <bcmdefs.h>
40
41/* How many pages do we try to swap or page in/out together? */
42int page_cluster;
43
44static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs);
45static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
46
47/*
48 * This path almost never happens for VM activity - pages are normally
49 * freed via pagevecs.  But it gets used by networking.
50 */
51static void __page_cache_release(struct page *page)
52{
53	if (PageLRU(page)) {
54		unsigned long flags;
55		struct zone *zone = page_zone(page);
56
57		spin_lock_irqsave(&zone->lru_lock, flags);
58		VM_BUG_ON(!PageLRU(page));
59		__ClearPageLRU(page);
60		del_page_from_lru(zone, page);
61		spin_unlock_irqrestore(&zone->lru_lock, flags);
62	}
63	free_hot_cold_page(page, 0);
64}
65
66static void put_compound_page(struct page *page)
67{
68	page = compound_head(page);
69	if (put_page_testzero(page)) {
70		compound_page_dtor *dtor;
71
72		dtor = get_compound_page_dtor(page);
73		(*dtor)(page);
74	}
75}
76
77void BCMFASTPATH_HOST put_page(struct page *page)
78{
79	if (unlikely(PageCompound(page)))
80		put_compound_page(page);
81	else if (put_page_testzero(page))
82		__page_cache_release(page);
83}
84EXPORT_SYMBOL(put_page);
85
86/**
87 * put_pages_list() - release a list of pages
88 * @pages: list of pages threaded on page->lru
89 *
90 * Release a list of pages which are strung together on page.lru.  Currently
91 * used by read_cache_pages() and related error recovery code.
92 */
93void put_pages_list(struct list_head *pages)
94{
95	while (!list_empty(pages)) {
96		struct page *victim;
97
98		victim = list_entry(pages->prev, struct page, lru);
99		list_del(&victim->lru);
100		page_cache_release(victim);
101	}
102}
103EXPORT_SYMBOL(put_pages_list);
104
105/*
106 * pagevec_move_tail() must be called with IRQ disabled.
107 * Otherwise this may cause nasty races.
108 */
109static void pagevec_move_tail(struct pagevec *pvec)
110{
111	int i;
112	int pgmoved = 0;
113	struct zone *zone = NULL;
114
115	for (i = 0; i < pagevec_count(pvec); i++) {
116		struct page *page = pvec->pages[i];
117		struct zone *pagezone = page_zone(page);
118
119		if (pagezone != zone) {
120			if (zone)
121				spin_unlock(&zone->lru_lock);
122			zone = pagezone;
123			spin_lock(&zone->lru_lock);
124		}
125		if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
126			int lru = page_lru_base_type(page);
127			list_move_tail(&page->lru, &zone->lru[lru].list);
128			pgmoved++;
129		}
130	}
131	if (zone)
132		spin_unlock(&zone->lru_lock);
133	__count_vm_events(PGROTATED, pgmoved);
134	release_pages(pvec->pages, pvec->nr, pvec->cold);
135	pagevec_reinit(pvec);
136}
137
138/*
139 * Writeback is about to end against a page which has been marked for immediate
140 * reclaim.  If it still appears to be reclaimable, move it to the tail of the
141 * inactive list.
142 */
143void  rotate_reclaimable_page(struct page *page)
144{
145	if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
146	    !PageUnevictable(page) && PageLRU(page)) {
147		struct pagevec *pvec;
148		unsigned long flags;
149
150		page_cache_get(page);
151		local_irq_save(flags);
152		pvec = &__get_cpu_var(lru_rotate_pvecs);
153		if (!pagevec_add(pvec, page))
154			pagevec_move_tail(pvec);
155		local_irq_restore(flags);
156	}
157}
158
159static void update_page_reclaim_stat(struct zone *zone, struct page *page,
160				     int file, int rotated)
161{
162	struct zone_reclaim_stat *reclaim_stat = &zone->reclaim_stat;
163	struct zone_reclaim_stat *memcg_reclaim_stat;
164
165	memcg_reclaim_stat = mem_cgroup_get_reclaim_stat_from_page(page);
166
167	reclaim_stat->recent_scanned[file]++;
168	if (rotated)
169		reclaim_stat->recent_rotated[file]++;
170
171	if (!memcg_reclaim_stat)
172		return;
173
174	memcg_reclaim_stat->recent_scanned[file]++;
175	if (rotated)
176		memcg_reclaim_stat->recent_rotated[file]++;
177}
178
179void activate_page(struct page *page)
180{
181	struct zone *zone = page_zone(page);
182
183	spin_lock_irq(&zone->lru_lock);
184	if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
185		int file = page_is_file_cache(page);
186		int lru = page_lru_base_type(page);
187		del_page_from_lru_list(zone, page, lru);
188
189		SetPageActive(page);
190		lru += LRU_ACTIVE;
191		add_page_to_lru_list(zone, page, lru);
192		__count_vm_event(PGACTIVATE);
193
194		update_page_reclaim_stat(zone, page, file, 1);
195	}
196	spin_unlock_irq(&zone->lru_lock);
197}
198
199/*
200 * Mark a page as having seen activity.
201 *
202 * inactive,unreferenced	->	inactive,referenced
203 * inactive,referenced		->	active,unreferenced
204 * active,unreferenced		->	active,referenced
205 */
206void mark_page_accessed(struct page *page)
207{
208	if (!PageActive(page) && !PageUnevictable(page) &&
209			PageReferenced(page) && PageLRU(page)) {
210		activate_page(page);
211		ClearPageReferenced(page);
212	} else if (!PageReferenced(page)) {
213		SetPageReferenced(page);
214	}
215}
216
217EXPORT_SYMBOL(mark_page_accessed);
218
219void __lru_cache_add(struct page *page, enum lru_list lru)
220{
221	struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru];
222
223	page_cache_get(page);
224	if (!pagevec_add(pvec, page))
225		____pagevec_lru_add(pvec, lru);
226	put_cpu_var(lru_add_pvecs);
227}
228EXPORT_SYMBOL(__lru_cache_add);
229
230/**
231 * lru_cache_add_lru - add a page to a page list
232 * @page: the page to be added to the LRU.
233 * @lru: the LRU list to which the page is added.
234 */
235void lru_cache_add_lru(struct page *page, enum lru_list lru)
236{
237	if (PageActive(page)) {
238		VM_BUG_ON(PageUnevictable(page));
239		ClearPageActive(page);
240	} else if (PageUnevictable(page)) {
241		VM_BUG_ON(PageActive(page));
242		ClearPageUnevictable(page);
243	}
244
245	VM_BUG_ON(PageLRU(page) || PageActive(page) || PageUnevictable(page));
246	__lru_cache_add(page, lru);
247}
248
249/**
250 * add_page_to_unevictable_list - add a page to the unevictable list
251 * @page:  the page to be added to the unevictable list
252 *
253 * Add page directly to its zone's unevictable list.  To avoid races with
254 * tasks that might be making the page evictable, through eg. munlock,
255 * munmap or exit, while it's not on the lru, we want to add the page
256 * while it's locked or otherwise "invisible" to other tasks.  This is
257 * difficult to do when using the pagevec cache, so bypass that.
258 */
259void add_page_to_unevictable_list(struct page *page)
260{
261	struct zone *zone = page_zone(page);
262
263	spin_lock_irq(&zone->lru_lock);
264	SetPageUnevictable(page);
265	SetPageLRU(page);
266	add_page_to_lru_list(zone, page, LRU_UNEVICTABLE);
267	spin_unlock_irq(&zone->lru_lock);
268}
269
270/*
271 * Drain pages out of the cpu's pagevecs.
272 * Either "cpu" is the current CPU, and preemption has already been
273 * disabled; or "cpu" is being hot-unplugged, and is already dead.
274 */
275static void drain_cpu_pagevecs(int cpu)
276{
277	struct pagevec *pvecs = per_cpu(lru_add_pvecs, cpu);
278	struct pagevec *pvec;
279	int lru;
280
281	for_each_lru(lru) {
282		pvec = &pvecs[lru - LRU_BASE];
283		if (pagevec_count(pvec))
284			____pagevec_lru_add(pvec, lru);
285	}
286
287	pvec = &per_cpu(lru_rotate_pvecs, cpu);
288	if (pagevec_count(pvec)) {
289		unsigned long flags;
290
291		/* No harm done if a racing interrupt already did this */
292		local_irq_save(flags);
293		pagevec_move_tail(pvec);
294		local_irq_restore(flags);
295	}
296}
297
298void lru_add_drain(void)
299{
300	drain_cpu_pagevecs(get_cpu());
301	put_cpu();
302}
303
304static void lru_add_drain_per_cpu(struct work_struct *dummy)
305{
306	lru_add_drain();
307}
308
309/*
310 * Returns 0 for success
311 */
312int lru_add_drain_all(void)
313{
314	return schedule_on_each_cpu(lru_add_drain_per_cpu);
315}
316
317/*
318 * Batched page_cache_release().  Decrement the reference count on all the
319 * passed pages.  If it fell to zero then remove the page from the LRU and
320 * free it.
321 *
322 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
323 * for the remainder of the operation.
324 *
325 * The locking in this function is against shrink_inactive_list(): we recheck
326 * the page count inside the lock to see whether shrink_inactive_list()
327 * grabbed the page via the LRU.  If it did, give up: shrink_inactive_list()
328 * will free it.
329 */
330void release_pages(struct page **pages, int nr, int cold)
331{
332	int i;
333	struct pagevec pages_to_free;
334	struct zone *zone = NULL;
335	unsigned long uninitialized_var(flags);
336
337	pagevec_init(&pages_to_free, cold);
338	for (i = 0; i < nr; i++) {
339		struct page *page = pages[i];
340
341		if (unlikely(PageCompound(page))) {
342			if (zone) {
343				spin_unlock_irqrestore(&zone->lru_lock, flags);
344				zone = NULL;
345			}
346			put_compound_page(page);
347			continue;
348		}
349
350		if (!put_page_testzero(page))
351			continue;
352
353		if (PageLRU(page)) {
354			struct zone *pagezone = page_zone(page);
355
356			if (pagezone != zone) {
357				if (zone)
358					spin_unlock_irqrestore(&zone->lru_lock,
359									flags);
360				zone = pagezone;
361				spin_lock_irqsave(&zone->lru_lock, flags);
362			}
363			VM_BUG_ON(!PageLRU(page));
364			__ClearPageLRU(page);
365			del_page_from_lru(zone, page);
366		}
367
368		if (!pagevec_add(&pages_to_free, page)) {
369			if (zone) {
370				spin_unlock_irqrestore(&zone->lru_lock, flags);
371				zone = NULL;
372			}
373			__pagevec_free(&pages_to_free);
374			pagevec_reinit(&pages_to_free);
375  		}
376	}
377	if (zone)
378		spin_unlock_irqrestore(&zone->lru_lock, flags);
379
380	pagevec_free(&pages_to_free);
381}
382
383/*
384 * The pages which we're about to release may be in the deferred lru-addition
385 * queues.  That would prevent them from really being freed right now.  That's
386 * OK from a correctness point of view but is inefficient - those pages may be
387 * cache-warm and we want to give them back to the page allocator ASAP.
388 *
389 * So __pagevec_release() will drain those queues here.  __pagevec_lru_add()
390 * and __pagevec_lru_add_active() call release_pages() directly to avoid
391 * mutual recursion.
392 */
393void __pagevec_release(struct pagevec *pvec)
394{
395	lru_add_drain();
396	release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
397	pagevec_reinit(pvec);
398}
399
400EXPORT_SYMBOL(__pagevec_release);
401
402/*
403 * Add the passed pages to the LRU, then drop the caller's refcount
404 * on them.  Reinitialises the caller's pagevec.
405 */
406void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru)
407{
408	int i;
409	struct zone *zone = NULL;
410
411	VM_BUG_ON(is_unevictable_lru(lru));
412
413	for (i = 0; i < pagevec_count(pvec); i++) {
414		struct page *page = pvec->pages[i];
415		struct zone *pagezone = page_zone(page);
416		int file;
417		int active;
418
419		if (pagezone != zone) {
420			if (zone)
421				spin_unlock_irq(&zone->lru_lock);
422			zone = pagezone;
423			spin_lock_irq(&zone->lru_lock);
424		}
425		VM_BUG_ON(PageActive(page));
426		VM_BUG_ON(PageUnevictable(page));
427		VM_BUG_ON(PageLRU(page));
428		SetPageLRU(page);
429		active = is_active_lru(lru);
430		file = is_file_lru(lru);
431		if (active)
432			SetPageActive(page);
433		update_page_reclaim_stat(zone, page, file, active);
434		add_page_to_lru_list(zone, page, lru);
435	}
436	if (zone)
437		spin_unlock_irq(&zone->lru_lock);
438	release_pages(pvec->pages, pvec->nr, pvec->cold);
439	pagevec_reinit(pvec);
440}
441
442EXPORT_SYMBOL(____pagevec_lru_add);
443
444/*
445 * Try to drop buffers from the pages in a pagevec
446 */
447void pagevec_strip(struct pagevec *pvec)
448{
449	int i;
450
451	for (i = 0; i < pagevec_count(pvec); i++) {
452		struct page *page = pvec->pages[i];
453
454		if (page_has_private(page) && trylock_page(page)) {
455			if (page_has_private(page))
456				try_to_release_page(page, 0);
457			unlock_page(page);
458		}
459	}
460}
461
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 */
478unsigned 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
485EXPORT_SYMBOL(pagevec_lookup);
486
487unsigned 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
495EXPORT_SYMBOL(pagevec_lookup_tag);
496
497/*
498 * Perform any setup for the swap system
499 */
500void __init swap_setup(void)
501{
502	unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
503
504#ifdef CONFIG_SWAP
505	bdi_init(swapper_space.backing_dev_info);
506#endif
507
508	/* Use a smaller cluster for small-memory machines */
509	if (megs < 16)
510		page_cluster = 2;
511	else
512		page_cluster = 3;
513	/*
514	 * Right now other parts of the system means that we
515	 * _really_ don't want to cluster much more
516	 */
517}
518