summaryrefslogtreecommitdiff
path: root/drivers/gpu/drm/ttm/ttm_page_alloc.c
blob: bd2a3b40cd129b30d4445a8cdca8adec2eb492f9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
/*
 * Copyright (c) Red Hat Inc.

 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sub license,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * Authors: Dave Airlie <airlied@redhat.com>
 *          Jerome Glisse <jglisse@redhat.com>
 *          Pauli Nieminen <suokkos@gmail.com>
 */

/* simple list based uncached page pool
 * - Pool collects resently freed pages for reuse
 * - Use page->lru to keep a free list
 * - doesn't track currently in use pages
 */

#define pr_fmt(fmt) "[TTM] " fmt

#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/highmem.h>
#include <linux/mm_types.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/seq_file.h> /* for seq_printf */
#include <linux/slab.h>
#include <linux/dma-mapping.h>

#include <linux/atomic.h>

#include <drm/ttm/ttm_bo_driver.h>
#include <drm/ttm/ttm_page_alloc.h>

#ifdef TTM_HAS_AGP
#include <asm/agp.h>
#endif

#define NUM_PAGES_TO_ALLOC		(PAGE_SIZE/sizeof(struct page *))
#define SMALL_ALLOCATION		16
#define FREE_ALL_PAGES			(~0U)
/* times are in msecs */
#define PAGE_FREE_INTERVAL		1000

/**
 * struct ttm_page_pool - Pool to reuse recently allocated uc/wc pages.
 *
 * @lock: Protects the shared pool from concurrnet access. Must be used with
 * irqsave/irqrestore variants because pool allocator maybe called from
 * delayed work.
 * @fill_lock: Prevent concurrent calls to fill.
 * @list: Pool of free uc/wc pages for fast reuse.
 * @gfp_flags: Flags to pass for alloc_page.
 * @npages: Number of pages in pool.
 */
struct ttm_page_pool {
	spinlock_t		lock;
	bool			fill_lock;
	struct list_head	list;
	gfp_t			gfp_flags;
	unsigned		npages;
	char			*name;
	unsigned long		nfrees;
	unsigned long		nrefills;
};

/**
 * Limits for the pool. They are handled without locks because only place where
 * they may change is in sysfs store. They won't have immediate effect anyway
 * so forcing serialization to access them is pointless.
 */

struct ttm_pool_opts {
	unsigned	alloc_size;
	unsigned	max_size;
	unsigned	small;
};

#define NUM_POOLS 4

/**
 * struct ttm_pool_manager - Holds memory pools for fst allocation
 *
 * Manager is read only object for pool code so it doesn't need locking.
 *
 * @free_interval: minimum number of jiffies between freeing pages from pool.
 * @page_alloc_inited: reference counting for pool allocation.
 * @work: Work that is used to shrink the pool. Work is only run when there is
 * some pages to free.
 * @small_allocation: Limit in number of pages what is small allocation.
 *
 * @pools: All pool objects in use.
 **/
struct ttm_pool_manager {
	struct kobject		kobj;
	struct shrinker		mm_shrink;
	struct ttm_pool_opts	options;

	union {
		struct ttm_page_pool	pools[NUM_POOLS];
		struct {
			struct ttm_page_pool	wc_pool;
			struct ttm_page_pool	uc_pool;
			struct ttm_page_pool	wc_pool_dma32;
			struct ttm_page_pool	uc_pool_dma32;
		} ;
	};
};

static struct attribute ttm_page_pool_max = {
	.name = "pool_max_size",
	.mode = S_IRUGO | S_IWUSR
};
static struct attribute ttm_page_pool_small = {
	.name = "pool_small_allocation",
	.mode = S_IRUGO | S_IWUSR
};
static struct attribute ttm_page_pool_alloc_size = {
	.name = "pool_allocation_size",
	.mode = S_IRUGO | S_IWUSR
};

static struct attribute *ttm_pool_attrs[] = {
	&ttm_page_pool_max,
	&ttm_page_pool_small,
	&ttm_page_pool_alloc_size,
	NULL
};

static void ttm_pool_kobj_release(struct kobject *kobj)
{
	struct ttm_pool_manager *m =
		container_of(kobj, struct ttm_pool_manager, kobj);
	kfree(m);
}

static ssize_t ttm_pool_store(struct kobject *kobj,
		struct attribute *attr, const char *buffer, size_t size)
{
	struct ttm_pool_manager *m =
		container_of(kobj, struct ttm_pool_manager, kobj);
	int chars;
	unsigned val;
	chars = sscanf(buffer, "%u", &val);
	if (chars == 0)
		return size;

	/* Convert kb to number of pages */
	val = val / (PAGE_SIZE >> 10);

	if (attr == &ttm_page_pool_max)
		m->options.max_size = val;
	else if (attr == &ttm_page_pool_small)
		m->options.small = val;
	else if (attr == &ttm_page_pool_alloc_size) {
		if (val > NUM_PAGES_TO_ALLOC*8) {
			pr_err("Setting allocation size to %lu is not allowed. Recommended size is %lu\n",
			       NUM_PAGES_TO_ALLOC*(PAGE_SIZE >> 7),
			       NUM_PAGES_TO_ALLOC*(PAGE_SIZE >> 10));
			return size;
		} else if (val > NUM_PAGES_TO_ALLOC) {
			pr_warn("Setting allocation size to larger than %lu is not recommended\n",
				NUM_PAGES_TO_ALLOC*(PAGE_SIZE >> 10));
		}
		m->options.alloc_size = val;
	}

	return size;
}

static ssize_t ttm_pool_show(struct kobject *kobj,
		struct attribute *attr, char *buffer)
{
	struct ttm_pool_manager *m =
		container_of(kobj, struct ttm_pool_manager, kobj);
	unsigned val = 0;

	if (attr == &ttm_page_pool_max)
		val = m->options.max_size;
	else if (attr == &ttm_page_pool_small)
		val = m->options.small;
	else if (attr == &ttm_page_pool_alloc_size)
		val = m->options.alloc_size;

	val = val * (PAGE_SIZE >> 10);

	return snprintf(buffer, PAGE_SIZE, "%u\n", val);
}

static const struct sysfs_ops ttm_pool_sysfs_ops = {
	.show = &ttm_pool_show,
	.store = &ttm_pool_store,
};

static struct kobj_type ttm_pool_kobj_type = {
	.release = &ttm_pool_kobj_release,
	.sysfs_ops = &ttm_pool_sysfs_ops,
	.default_attrs = ttm_pool_attrs,
};

static struct ttm_pool_manager *_manager;

#ifndef CONFIG_X86
static int set_pages_array_wb(struct page **pages, int addrinarray)
{
#ifdef TTM_HAS_AGP
	int i;

	for (i = 0; i < addrinarray; i++)
		unmap_page_from_agp(pages[i]);
#endif
	return 0;
}

static int set_pages_array_wc(struct page **pages, int addrinarray)
{
#ifdef TTM_HAS_AGP
	int i;

	for (i = 0; i < addrinarray; i++)
		map_page_into_agp(pages[i]);
#endif
	return 0;
}

static int set_pages_array_uc(struct page **pages, int addrinarray)
{
#ifdef TTM_HAS_AGP
	int i;

	for (i = 0; i < addrinarray; i++)
		map_page_into_agp(pages[i]);
#endif
	return 0;
}
#endif

/**
 * Select the right pool or requested caching state and ttm flags. */
static struct ttm_page_pool *ttm_get_pool(int flags,
		enum ttm_caching_state cstate)
{
	int pool_index;

	if (cstate == tt_cached)
		return NULL;

	if (cstate == tt_wc)
		pool_index = 0x0;
	else
		pool_index = 0x1;

	if (flags & TTM_PAGE_FLAG_DMA32)
		pool_index |= 0x2;

	return &_manager->pools[pool_index];
}

/* set memory back to wb and free the pages. */
static void ttm_pages_put(struct page *pages[], unsigned npages)
{
	unsigned i;
	if (set_pages_array_wb(pages, npages))
		pr_err("Failed to set %d pages to wb!\n", npages);
	for (i = 0; i < npages; ++i)
		__free_page(pages[i]);
}

static void ttm_pool_update_free_locked(struct ttm_page_pool *pool,
		unsigned freed_pages)
{
	pool->npages -= freed_pages;
	pool->nfrees += freed_pages;
}

/**
 * Free pages from pool.
 *
 * To prevent hogging the ttm_swap process we only free NUM_PAGES_TO_ALLOC
 * number of pages in one go.
 *
 * @pool: to free the pages from
 * @free_all: If set to true will free all pages in pool
 **/
static int ttm_page_pool_free(struct ttm_page_pool *pool, unsigned nr_free)
{
	unsigned long irq_flags;
	struct page *p;
	struct page **pages_to_free;
	unsigned freed_pages = 0,
		 npages_to_free = nr_free;

	if (NUM_PAGES_TO_ALLOC < nr_free)
		npages_to_free = NUM_PAGES_TO_ALLOC;

	pages_to_free = kmalloc(npages_to_free * sizeof(struct page *),
			GFP_KERNEL);
	if (!pages_to_free) {
		pr_err("Failed to allocate memory for pool free operation\n");
		return 0;
	}

restart:
	spin_lock_irqsave(&pool->lock, irq_flags);

	list_for_each_entry_reverse(p, &pool->list, lru) {
		if (freed_pages >= npages_to_free)
			break;

		pages_to_free[freed_pages++] = p;
		/* We can only remove NUM_PAGES_TO_ALLOC at a time. */
		if (freed_pages >= NUM_PAGES_TO_ALLOC) {
			/* remove range of pages from the pool */
			__list_del(p->lru.prev, &pool->list);

			ttm_pool_update_free_locked(pool, freed_pages);
			/**
			 * Because changing page caching is costly
			 * we unlock the pool to prevent stalling.
			 */
			spin_unlock_irqrestore(&pool->lock, irq_flags);

			ttm_pages_put(pages_to_free, freed_pages);
			if (likely(nr_free != FREE_ALL_PAGES))
				nr_free -= freed_pages;

			if (NUM_PAGES_TO_ALLOC >= nr_free)
				npages_to_free = nr_free;
			else
				npages_to_free = NUM_PAGES_TO_ALLOC;

			freed_pages = 0;

			/* free all so restart the processing */
			if (nr_free)
				goto restart;

			/* Not allowed to fall through or break because
			 * following context is inside spinlock while we are
			 * outside here.
			 */
			goto out;

		}
	}

	/* remove range of pages from the pool */
	if (freed_pages) {
		__list_del(&p->lru, &pool->list);

		ttm_pool_update_free_locked(pool, freed_pages);
		nr_free -= freed_pages;
	}

	spin_unlock_irqrestore(&pool->lock, irq_flags);

	if (freed_pages)
		ttm_pages_put(pages_to_free, freed_pages);
out:
	kfree(pages_to_free);
	return nr_free;
}

/* Get good estimation how many pages are free in pools */
static int ttm_pool_get_num_unused_pages(void)
{
	unsigned i;
	int total = 0;
	for (i = 0; i < NUM_POOLS; ++i)
		total += _manager->pools[i].npages;

	return total;
}

/**
 * Callback for mm to request pool to reduce number of page held.
 */
static int ttm_pool_mm_shrink(struct shrinker *shrink,
			      struct shrink_control *sc)
{
	static atomic_t start_pool = ATOMIC_INIT(0);
	unsigned i;
	unsigned pool_offset = atomic_add_return(1, &start_pool);
	struct ttm_page_pool *pool;
	int shrink_pages = sc->nr_to_scan;

	pool_offset = pool_offset % NUM_POOLS;
	/* select start pool in round robin fashion */
	for (i = 0; i < NUM_POOLS; ++i) {
		unsigned nr_free = shrink_pages;
		if (shrink_pages == 0)
			break;
		pool = &_manager->pools[(i + pool_offset)%NUM_POOLS];
		shrink_pages = ttm_page_pool_free(pool, nr_free);
	}
	/* return estimated number of unused pages in pool */
	return ttm_pool_get_num_unused_pages();
}

static void ttm_pool_mm_shrink_init(struct ttm_pool_manager *manager)
{
	manager->mm_shrink.shrink = &ttm_pool_mm_shrink;
	manager->mm_shrink.seeks = 1;
	register_shrinker(&manager->mm_shrink);
}

static void ttm_pool_mm_shrink_fini(struct ttm_pool_manager *manager)
{
	unregister_shrinker(&manager->mm_shrink);
}

static int ttm_set_pages_caching(struct page **pages,
		enum ttm_caching_state cstate, unsigned cpages)
{
	int r = 0;
	/* Set page caching */
	switch (cstate) {
	case tt_uncached:
		r = set_pages_array_uc(pages, cpages);
		if (r)
			pr_err("Failed to set %d pages to uc!\n", cpages);
		break;
	case tt_wc:
		r = set_pages_array_wc(pages, cpages);
		if (r)
			pr_err("Failed to set %d pages to wc!\n", cpages);
		break;
	default:
		break;
	}
	return r;
}

/**
 * Free pages the pages that failed to change the caching state. If there is
 * any pages that have changed their caching state already put them to the
 * pool.
 */
static void ttm_handle_caching_state_failure(struct list_head *pages,
		int ttm_flags, enum ttm_caching_state cstate,
		struct page **failed_pages, unsigned cpages)
{
	unsigned i;
	/* Failed pages have to be freed */
	for (i = 0; i < cpages; ++i) {
		list_del(&failed_pages[i]->lru);
		__free_page(failed_pages[i]);
	}
}

/**
 * Allocate new pages with correct caching.
 *
 * This function is reentrant if caller updates count depending on number of
 * pages returned in pages array.
 */
static int ttm_alloc_new_pages(struct list_head *pages, gfp_t gfp_flags,
		int ttm_flags, enum ttm_caching_state cstate, unsigned count)
{
	struct page **caching_array;
	struct page *p;
	int r = 0;
	unsigned i, cpages;
	unsigned max_cpages = min(count,
			(unsigned)(PAGE_SIZE/sizeof(struct page *)));

	/* allocate array for page caching change */
	caching_array = kmalloc(max_cpages*sizeof(struct page *), GFP_KERNEL);

	if (!caching_array) {
		pr_err("Unable to allocate table for new pages\n");
		return -ENOMEM;
	}

	for (i = 0, cpages = 0; i < count; ++i) {
		p = alloc_page(gfp_flags);

		if (!p) {
			pr_err("Unable to get page %u\n", i);

			/* store already allocated pages in the pool after
			 * setting the caching state */
			if (cpages) {
				r = ttm_set_pages_caching(caching_array,
							  cstate, cpages);
				if (r)
					ttm_handle_caching_state_failure(pages,
						ttm_flags, cstate,
						caching_array, cpages);
			}
			r = -ENOMEM;
			goto out;
		}

#ifdef CONFIG_HIGHMEM
		/* gfp flags of highmem page should never be dma32 so we
		 * we should be fine in such case
		 */
		if (!PageHighMem(p))
#endif
		{
			caching_array[cpages++] = p;
			if (cpages == max_cpages) {

				r = ttm_set_pages_caching(caching_array,
						cstate, cpages);
				if (r) {
					ttm_handle_caching_state_failure(pages,
						ttm_flags, cstate,
						caching_array, cpages);
					goto out;
				}
				cpages = 0;
			}
		}

		list_add(&p->lru, pages);
	}

	if (cpages) {
		r = ttm_set_pages_caching(caching_array, cstate, cpages);
		if (r)
			ttm_handle_caching_state_failure(pages,
					ttm_flags, cstate,
					caching_array, cpages);
	}
out:
	kfree(caching_array);

	return r;
}

/**
 * Fill the given pool if there aren't enough pages and the requested number of
 * pages is small.
 */
static void ttm_page_pool_fill_locked(struct ttm_page_pool *pool,
		int ttm_flags, enum ttm_caching_state cstate, unsigned count,
		unsigned long *irq_flags)
{
	struct page *p;
	int r;
	unsigned cpages = 0;
	/**
	 * Only allow one pool fill operation at a time.
	 * If pool doesn't have enough pages for the allocation new pages are
	 * allocated from outside of pool.
	 */
	if (pool->fill_lock)
		return;

	pool->fill_lock = true;

	/* If allocation request is small and there are not enough
	 * pages in a pool we fill the pool up first. */
	if (count < _manager->options.small
		&& count > pool->npages) {
		struct list_head new_pages;
		unsigned alloc_size = _manager->options.alloc_size;

		/**
		 * Can't change page caching if in irqsave context. We have to
		 * drop the pool->lock.
		 */
		spin_unlock_irqrestore(&pool->lock, *irq_flags);

		INIT_LIST_HEAD(&new_pages);
		r = ttm_alloc_new_pages(&new_pages, pool->gfp_flags, ttm_flags,
				cstate,	alloc_size);
		spin_lock_irqsave(&pool->lock, *irq_flags);

		if (!r) {
			list_splice(&new_pages, &pool->list);
			++pool->nrefills;
			pool->npages += alloc_size;
		} else {
			pr_err("Failed to fill pool (%p)\n", pool);
			/* If we have any pages left put them to the pool. */
			list_for_each_entry(p, &pool->list, lru) {
				++cpages;
			}
			list_splice(&new_pages, &pool->list);
			pool->npages += cpages;
		}

	}
	pool->fill_lock = false;
}

/**
 * Cut 'count' number of pages from the pool and put them on the return list.
 *
 * @return count of pages still required to fulfill the request.
 */
static unsigned ttm_page_pool_get_pages(struct ttm_page_pool *pool,
					struct list_head *pages,
					int ttm_flags,
					enum ttm_caching_state cstate,
					unsigned count)
{
	unsigned long irq_flags;
	struct list_head *p;
	unsigned i;

	spin_lock_irqsave(&pool->lock, irq_flags);
	ttm_page_pool_fill_locked(pool, ttm_flags, cstate, count, &irq_flags);

	if (count >= pool->npages) {
		/* take all pages from the pool */
		list_splice_init(&pool->list, pages);
		count -= pool->npages;
		pool->npages = 0;
		goto out;
	}
	/* find the last pages to include for requested number of pages. Split
	 * pool to begin and halve it to reduce search space. */
	if (count <= pool->npages/2) {
		i = 0;
		list_for_each(p, &pool->list) {
			if (++i == count)
				break;
		}
	} else {
		i = pool->npages + 1;
		list_for_each_prev(p, &pool->list) {
			if (--i == count)
				break;
		}
	}
	/* Cut 'count' number of pages from the pool */
	list_cut_position(pages, &pool->list, p);
	pool->npages -= count;
	count = 0;
out:
	spin_unlock_irqrestore(&pool->lock, irq_flags);
	return count;
}

/* Put all pages in pages list to correct pool to wait for reuse */
static void ttm_put_pages(struct page **pages, unsigned npages, int flags,
			  enum ttm_caching_state cstate)
{
	unsigned long irq_flags;
	struct ttm_page_pool *pool = ttm_get_pool(flags, cstate);
	unsigned i;

	if (pool == NULL) {
		/* No pool for this memory type so free the pages */
		for (i = 0; i < npages; i++) {
			if (pages[i]) {
				if (page_count(pages[i]) != 1)
					pr_err("Erroneous page count. Leaking pages.\n");
				__free_page(pages[i]);
				pages[i] = NULL;
			}
		}
		return;
	}

	spin_lock_irqsave(&pool->lock, irq_flags);
	for (i = 0; i < npages; i++) {
		if (pages[i]) {
			if (page_count(pages[i]) != 1)
				pr_err("Erroneous page count. Leaking pages.\n");
			list_add_tail(&pages[i]->lru, &pool->list);
			pages[i] = NULL;
			pool->npages++;
		}
	}
	/* Check that we don't go over the pool limit */
	npages = 0;
	if (pool->npages > _manager->options.max_size) {
		npages = pool->npages - _manager->options.max_size;
		/* free at least NUM_PAGES_TO_ALLOC number of pages
		 * to reduce calls to set_memory_wb */
		if (npages < NUM_PAGES_TO_ALLOC)
			npages = NUM_PAGES_TO_ALLOC;
	}
	spin_unlock_irqrestore(&pool->lock, irq_flags);
	if (npages)
		ttm_page_pool_free(pool, npages);
}

/*
 * On success pages list will hold count number of correctly
 * cached pages.
 */
static int ttm_get_pages(struct page **pages, unsigned npages, int flags,
			 enum ttm_caching_state cstate)
{
	struct ttm_page_pool *pool = ttm_get_pool(flags, cstate);
	struct list_head plist;
	struct page *p = NULL;
	gfp_t gfp_flags = GFP_USER;
	unsigned count;
	int r;

	/* set zero flag for page allocation if required */
	if (flags & TTM_PAGE_FLAG_ZERO_ALLOC)
		gfp_flags |= __GFP_ZERO;

	/* No pool for cached pages */
	if (pool == NULL) {
		if (flags & TTM_PAGE_FLAG_DMA32)
			gfp_flags |= GFP_DMA32;
		else
			gfp_flags |= GFP_HIGHUSER;

		for (r = 0; r < npages; ++r) {
			p = alloc_page(gfp_flags);
			if (!p) {

				pr_err("Unable to allocate page\n");
				return -ENOMEM;
			}

			pages[r] = p;
		}
		return 0;
	}

	/* combine zero flag to pool flags */
	gfp_flags |= pool->gfp_flags;

	/* First we take pages from the pool */
	INIT_LIST_HEAD(&plist);
	npages = ttm_page_pool_get_pages(pool, &plist, flags, cstate, npages);
	count = 0;
	list_for_each_entry(p, &plist, lru) {
		pages[count++] = p;
	}

	/* clear the pages coming from the pool if requested */
	if (flags & TTM_PAGE_FLAG_ZERO_ALLOC) {
		list_for_each_entry(p, &plist, lru) {
			if (PageHighMem(p))
				clear_highpage(p);
			else
				clear_page(page_address(p));
		}
	}

	/* If pool didn't have enough pages allocate new one. */
	if (npages > 0) {
		/* ttm_alloc_new_pages doesn't reference pool so we can run
		 * multiple requests in parallel.
		 **/
		INIT_LIST_HEAD(&plist);
		r = ttm_alloc_new_pages(&plist, gfp_flags, flags, cstate, npages);
		list_for_each_entry(p, &plist, lru) {
			pages[count++] = p;
		}
		if (r) {
			/* If there is any pages in the list put them back to
			 * the pool. */
			pr_err("Failed to allocate extra pages for large request\n");
			ttm_put_pages(pages, count, flags, cstate);
			return r;
		}
	}

	return 0;
}

static void ttm_page_pool_init_locked(struct ttm_page_pool *pool, int flags,
		char *name)
{
	spin_lock_init(&pool->lock);
	pool->fill_lock = false;
	INIT_LIST_HEAD(&pool->list);
	pool->npages = pool->nfrees = 0;
	pool->gfp_flags = flags;
	pool->name = name;
}

int ttm_page_alloc_init(struct ttm_mem_global *glob, unsigned max_pages)
{
	int ret;

	WARN_ON(_manager);

	pr_info("Initializing pool allocator\n");

	_manager = kzalloc(sizeof(*_manager), GFP_KERNEL);

	ttm_page_pool_init_locked(&_manager->wc_pool, GFP_HIGHUSER, "wc");

	ttm_page_pool_init_locked(&_manager->uc_pool, GFP_HIGHUSER, "uc");

	ttm_page_pool_init_locked(&_manager->wc_pool_dma32,
				  GFP_USER | GFP_DMA32, "wc dma");

	ttm_page_pool_init_locked(&_manager->uc_pool_dma32,
				  GFP_USER | GFP_DMA32, "uc dma");

	_manager->options.max_size = max_pages;
	_manager->options.small = SMALL_ALLOCATION;
	_manager->options.alloc_size = NUM_PAGES_TO_ALLOC;

	ret = kobject_init_and_add(&_manager->kobj, &ttm_pool_kobj_type,
				   &glob->kobj, "pool");
	if (unlikely(ret != 0)) {
		kobject_put(&_manager->kobj);
		_manager = NULL;
		return ret;
	}

	ttm_pool_mm_shrink_init(_manager);

	return 0;
}

void ttm_page_alloc_fini(void)
{
	int i;

	pr_info("Finalizing pool allocator\n");
	ttm_pool_mm_shrink_fini(_manager);

	for (i = 0; i < NUM_POOLS; ++i)
		ttm_page_pool_free(&_manager->pools[i], FREE_ALL_PAGES);

	kobject_put(&_manager->kobj);
	_manager = NULL;
}

int ttm_pool_populate(struct ttm_tt *ttm)
{
	struct ttm_mem_global *mem_glob = ttm->glob->mem_glob;
	unsigned i;
	int ret;

	if (ttm->state != tt_unpopulated)
		return 0;

	for (i = 0; i < ttm->num_pages; ++i) {
		ret = ttm_get_pages(&ttm->pages[i], 1,
				    ttm->page_flags,
				    ttm->caching_state);
		if (ret != 0) {
			ttm_pool_unpopulate(ttm);
			return -ENOMEM;
		}

		ret = ttm_mem_global_alloc_page(mem_glob, ttm->pages[i],
						false, false);
		if (unlikely(ret != 0)) {
			ttm_pool_unpopulate(ttm);
			return -ENOMEM;
		}
	}

	if (unlikely(ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)) {
		ret = ttm_tt_swapin(ttm);
		if (unlikely(ret != 0)) {
			ttm_pool_unpopulate(ttm);
			return ret;
		}
	}

	ttm->state = tt_unbound;
	return 0;
}
EXPORT_SYMBOL(ttm_pool_populate);

void ttm_pool_unpopulate(struct ttm_tt *ttm)
{
	unsigned i;

	for (i = 0; i < ttm->num_pages; ++i) {
		if (ttm->pages[i]) {
			ttm_mem_global_free_page(ttm->glob->mem_glob,
						 ttm->pages[i]);
			ttm_put_pages(&ttm->pages[i], 1,
				      ttm->page_flags,
				      ttm->caching_state);
		}
	}
	ttm->state = tt_unpopulated;
}
EXPORT_SYMBOL(ttm_pool_unpopulate);

int ttm_page_alloc_debugfs(struct seq_file *m, void *data)
{
	struct ttm_page_pool *p;
	unsigned i;
	char *h[] = {"pool", "refills", "pages freed", "size"};
	if (!_manager) {
		seq_printf(m, "No pool allocator running.\n");
		return 0;
	}
	seq_printf(m, "%6s %12s %13s %8s\n",
			h[0], h[1], h[2], h[3]);
	for (i = 0; i < NUM_POOLS; ++i) {
		p = &_manager->pools[i];

		seq_printf(m, "%6s %12ld %13ld %8d\n",
				p->name, p->nrefills,
				p->nfrees, p->npages);
	}
	return 0;
}
EXPORT_SYMBOL(ttm_page_alloc_debugfs);