page_alloc.c 130 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
/*
 *  linux/mm/page_alloc.c
 *
 *  Manages the free list, the system allocates free pages here.
 *  Note that kmalloc() lives in slab.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *  Swap reorganised 29.12.95, Stephen Tweedie
 *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
 *  Reshaped it to be a zoned allocator, Ingo Molnar, Red Hat, 1999
 *  Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
 *  Zone balancing, Kanoj Sarcar, SGI, Jan 2000
 *  Per cpu hot/cold page lists, bulk allocation, Martin J. Bligh, Sept 2002
 *          (lots of bits borrowed from Ingo Molnar & Andrew Morton)
 */

#include <linux/stddef.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/interrupt.h>
#include <linux/pagemap.h>
22
#include <linux/jiffies.h>
Linus Torvalds's avatar
Linus Torvalds committed
23
24
#include <linux/bootmem.h>
#include <linux/compiler.h>
25
#include <linux/kernel.h>
Linus Torvalds's avatar
Linus Torvalds committed
26
27
28
29
30
#include <linux/module.h>
#include <linux/suspend.h>
#include <linux/pagevec.h>
#include <linux/blkdev.h>
#include <linux/slab.h>
31
#include <linux/oom.h>
Linus Torvalds's avatar
Linus Torvalds committed
32
33
34
35
36
#include <linux/notifier.h>
#include <linux/topology.h>
#include <linux/sysctl.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
37
#include <linux/memory_hotplug.h>
Linus Torvalds's avatar
Linus Torvalds committed
38
39
#include <linux/nodemask.h>
#include <linux/vmalloc.h>
40
#include <linux/mempolicy.h>
41
#include <linux/stop_machine.h>
42
43
#include <linux/sort.h>
#include <linux/pfn.h>
44
#include <linux/backing-dev.h>
45
#include <linux/fault-inject.h>
46
#include <linux/page-isolation.h>
47
#include <linux/page_cgroup.h>
48
#include <linux/debugobjects.h>
Linus Torvalds's avatar
Linus Torvalds committed
49
50

#include <asm/tlbflush.h>
51
#include <asm/div64.h>
Linus Torvalds's avatar
Linus Torvalds committed
52
53
54
#include "internal.h"

/*
55
 * Array of node states.
Linus Torvalds's avatar
Linus Torvalds committed
56
 */
57
58
59
60
61
62
63
64
65
66
67
68
69
nodemask_t node_states[NR_NODE_STATES] __read_mostly = {
	[N_POSSIBLE] = NODE_MASK_ALL,
	[N_ONLINE] = { { [0] = 1UL } },
#ifndef CONFIG_NUMA
	[N_NORMAL_MEMORY] = { { [0] = 1UL } },
#ifdef CONFIG_HIGHMEM
	[N_HIGH_MEMORY] = { { [0] = 1UL } },
#endif
	[N_CPU] = { { [0] = 1UL } },
#endif	/* NUMA */
};
EXPORT_SYMBOL(node_states);

70
unsigned long totalram_pages __read_mostly;
71
unsigned long totalreserve_pages __read_mostly;
72
int percpu_pagelist_fraction;
Linus Torvalds's avatar
Linus Torvalds committed
73

74
75
76
77
#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
int pageblock_order __read_mostly;
#endif

78
static void __free_pages_ok(struct page *page, unsigned int order);
79

Linus Torvalds's avatar
Linus Torvalds committed
80
81
82
83
84
85
86
/*
 * results with 256, 32 in the lowmem_reserve sysctl:
 *	1G machine -> (16M dma, 800M-16M normal, 1G-800M high)
 *	1G machine -> (16M dma, 784M normal, 224M high)
 *	NORMAL allocation will leave 784M/256 of ram reserved in the ZONE_DMA
 *	HIGHMEM allocation will leave 224M/32 of ram reserved in ZONE_NORMAL
 *	HIGHMEM allocation will (224M+784M)/256 of ram reserved in ZONE_DMA
87
88
89
 *
 * TBD: should special case ZONE_DMA32 machines here - in those we normally
 * don't need any ZONE_NORMAL reservation
Linus Torvalds's avatar
Linus Torvalds committed
90
 */
91
int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
92
#ifdef CONFIG_ZONE_DMA
93
	 256,
94
#endif
95
#ifdef CONFIG_ZONE_DMA32
96
	 256,
97
#endif
98
#ifdef CONFIG_HIGHMEM
Mel Gorman's avatar
Mel Gorman committed
99
	 32,
100
#endif
Mel Gorman's avatar
Mel Gorman committed
101
	 32,
102
};
Linus Torvalds's avatar
Linus Torvalds committed
103
104
105

EXPORT_SYMBOL(totalram_pages);

106
static char * const zone_names[MAX_NR_ZONES] = {
107
#ifdef CONFIG_ZONE_DMA
108
	 "DMA",
109
#endif
110
#ifdef CONFIG_ZONE_DMA32
111
	 "DMA32",
112
#endif
113
	 "Normal",
114
#ifdef CONFIG_HIGHMEM
Mel Gorman's avatar
Mel Gorman committed
115
	 "HighMem",
116
#endif
Mel Gorman's avatar
Mel Gorman committed
117
	 "Movable",
118
119
};

Linus Torvalds's avatar
Linus Torvalds committed
120
121
int min_free_kbytes = 1024;

122
123
unsigned long __meminitdata nr_kernel_pages;
unsigned long __meminitdata nr_all_pages;
124
static unsigned long __meminitdata dma_reserve;
Linus Torvalds's avatar
Linus Torvalds committed
125

126
127
#ifdef CONFIG_ARCH_POPULATES_NODE_MAP
  /*
Simon Arlott's avatar
Simon Arlott committed
128
   * MAX_ACTIVE_REGIONS determines the maximum number of distinct
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
   * ranges of memory (RAM) that may be registered with add_active_range().
   * Ranges passed to add_active_range() will be merged if possible
   * so the number of times add_active_range() can be called is
   * related to the number of nodes and the number of holes
   */
  #ifdef CONFIG_MAX_ACTIVE_REGIONS
    /* Allow an architecture to set MAX_ACTIVE_REGIONS to save memory */
    #define MAX_ACTIVE_REGIONS CONFIG_MAX_ACTIVE_REGIONS
  #else
    #if MAX_NUMNODES >= 32
      /* If there can be many nodes, allow up to 50 holes per node */
      #define MAX_ACTIVE_REGIONS (MAX_NUMNODES*50)
    #else
      /* By default, allow up to 256 distinct regions */
      #define MAX_ACTIVE_REGIONS 256
    #endif
  #endif

147
148
149
150
  static struct node_active_region __meminitdata early_node_map[MAX_ACTIVE_REGIONS];
  static int __meminitdata nr_nodemap_entries;
  static unsigned long __meminitdata arch_zone_lowest_possible_pfn[MAX_NR_ZONES];
  static unsigned long __meminitdata arch_zone_highest_possible_pfn[MAX_NR_ZONES];
151
#ifdef CONFIG_MEMORY_HOTPLUG_RESERVE
152
153
  static unsigned long __meminitdata node_boundary_start_pfn[MAX_NUMNODES];
  static unsigned long __meminitdata node_boundary_end_pfn[MAX_NUMNODES];
154
#endif /* CONFIG_MEMORY_HOTPLUG_RESERVE */
Adrian Bunk's avatar
Adrian Bunk committed
155
  static unsigned long __initdata required_kernelcore;
156
  static unsigned long __initdata required_movablecore;
Adrian Bunk's avatar
Adrian Bunk committed
157
  static unsigned long __meminitdata zone_movable_pfn[MAX_NUMNODES];
Mel Gorman's avatar
Mel Gorman committed
158
159
160
161

  /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
  int movable_zone;
  EXPORT_SYMBOL(movable_zone);
162
163
#endif /* CONFIG_ARCH_POPULATES_NODE_MAP */

Miklos Szeredi's avatar
Miklos Szeredi committed
164
165
166
167
168
#if MAX_NUMNODES > 1
int nr_node_ids __read_mostly = MAX_NUMNODES;
EXPORT_SYMBOL(nr_node_ids);
#endif

169
170
int page_group_by_mobility_disabled __read_mostly;

171
172
173
174
175
176
static void set_pageblock_migratetype(struct page *page, int migratetype)
{
	set_pageblock_flags_group(page, (unsigned long)migratetype,
					PB_migrate, PB_migrate_end);
}

Nick Piggin's avatar
Nick Piggin committed
177
#ifdef CONFIG_DEBUG_VM
178
static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
179
{
180
181
182
	int ret = 0;
	unsigned seq;
	unsigned long pfn = page_to_pfn(page);
183

184
185
186
187
188
189
190
191
192
	do {
		seq = zone_span_seqbegin(zone);
		if (pfn >= zone->zone_start_pfn + zone->spanned_pages)
			ret = 1;
		else if (pfn < zone->zone_start_pfn)
			ret = 1;
	} while (zone_span_seqretry(zone, seq));

	return ret;
193
194
195
196
}

static int page_is_consistent(struct zone *zone, struct page *page)
{
197
	if (!pfn_valid_within(page_to_pfn(page)))
198
		return 0;
Linus Torvalds's avatar
Linus Torvalds committed
199
	if (zone != page_zone(page))
200
201
202
203
204
205
206
207
208
209
		return 0;

	return 1;
}
/*
 * Temporary debugging check for pages not lying within a given zone.
 */
static int bad_range(struct zone *zone, struct page *page)
{
	if (page_outside_zone_boundaries(zone, page))
Linus Torvalds's avatar
Linus Torvalds committed
210
		return 1;
211
212
213
	if (!page_is_consistent(zone, page))
		return 1;

Linus Torvalds's avatar
Linus Torvalds committed
214
215
	return 0;
}
Nick Piggin's avatar
Nick Piggin committed
216
217
218
219
220
221
222
#else
static inline int bad_range(struct zone *zone, struct page *page)
{
	return 0;
}
#endif

223
static void bad_page(struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
224
{
225
226
227
228
229
230
231
232
	printk(KERN_EMERG "Bad page state in process %s  pfn:%05lx\n",
		current->comm, page_to_pfn(page));
	printk(KERN_EMERG
		"page:%p flags:%p count:%d mapcount:%d mapping:%p index:%lx\n",
		page, (void *)page->flags, page_count(page),
		page_mapcount(page), page->mapping, page->index);
	printk(KERN_EMERG "Trying to fix it up, but a reboot is needed\n");

Linus Torvalds's avatar
Linus Torvalds committed
233
	dump_stack();
234
235
236

	/* Leave bad fields for debug, except PageBuddy could make trouble */
	__ClearPageBuddy(page);
237
	add_taint(TAINT_BAD_PAGE);
Linus Torvalds's avatar
Linus Torvalds committed
238
239
240
241
242
243
244
245
246
247
248
249
}

/*
 * Higher-order pages are called "compound pages".  They are structured thusly:
 *
 * The first PAGE_SIZE page is called the "head page".
 *
 * The remaining PAGE_SIZE pages are called "tail pages".
 *
 * All pages have PG_compound set.  All pages have their ->private pointing at
 * the head page (even the head page has this).
 *
250
251
252
 * The first tail page's ->lru.next holds the address of the compound page's
 * put_page() function.  Its ->lru.prev holds the order of allocation.
 * This usage means that zero-order pages may not be compound.
Linus Torvalds's avatar
Linus Torvalds committed
253
 */
254
255
256

static void free_compound_page(struct page *page)
{
257
	__free_pages_ok(page, compound_order(page));
258
259
}

260
void prep_compound_page(struct page *page, unsigned long order)
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
{
	int i;
	int nr_pages = 1 << order;

	set_compound_page_dtor(page, free_compound_page);
	set_compound_order(page, order);
	__SetPageHead(page);
	for (i = 1; i < nr_pages; i++) {
		struct page *p = page + i;

		__SetPageTail(p);
		p->first_page = page;
	}
}

#ifdef CONFIG_HUGETLBFS
void prep_compound_gigantic_page(struct page *page, unsigned long order)
Linus Torvalds's avatar
Linus Torvalds committed
278
279
280
{
	int i;
	int nr_pages = 1 << order;
281
	struct page *p = page + 1;
Linus Torvalds's avatar
Linus Torvalds committed
282

283
	set_compound_page_dtor(page, free_compound_page);
284
	set_compound_order(page, order);
285
	__SetPageHead(page);
286
	for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) {
287
288
		__SetPageTail(p);
		p->first_page = page;
Linus Torvalds's avatar
Linus Torvalds committed
289
290
	}
}
291
#endif
Linus Torvalds's avatar
Linus Torvalds committed
292

293
static int destroy_compound_page(struct page *page, unsigned long order)
Linus Torvalds's avatar
Linus Torvalds committed
294
295
296
{
	int i;
	int nr_pages = 1 << order;
297
	int bad = 0;
Linus Torvalds's avatar
Linus Torvalds committed
298

299
300
	if (unlikely(compound_order(page) != order) ||
	    unlikely(!PageHead(page))) {
301
		bad_page(page);
302
303
		bad++;
	}
Linus Torvalds's avatar
Linus Torvalds committed
304

305
	__ClearPageHead(page);
306

307
308
	for (i = 1; i < nr_pages; i++) {
		struct page *p = page + i;
Linus Torvalds's avatar
Linus Torvalds committed
309

310
		if (unlikely(!PageTail(p) | (p->first_page != page))) {
311
			bad_page(page);
312
313
			bad++;
		}
314
		__ClearPageTail(p);
Linus Torvalds's avatar
Linus Torvalds committed
315
	}
316
317

	return bad;
Linus Torvalds's avatar
Linus Torvalds committed
318
319
}

Nick Piggin's avatar
Nick Piggin committed
320
321
322
323
static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags)
{
	int i;

324
325
326
327
	/*
	 * clear_highpage() will use KM_USER0, so it's a bug to use __GFP_ZERO
	 * and __GFP_HIGHMEM from hard or soft interrupt context.
	 */
Nick Piggin's avatar
Nick Piggin committed
328
	VM_BUG_ON((gfp_flags & __GFP_HIGHMEM) && in_interrupt());
Nick Piggin's avatar
Nick Piggin committed
329
330
331
332
	for (i = 0; i < (1 << order); i++)
		clear_highpage(page + i);
}

333
334
static inline void set_page_order(struct page *page, int order)
{
335
	set_page_private(page, order);
336
	__SetPageBuddy(page);
Linus Torvalds's avatar
Linus Torvalds committed
337
338
339
340
}

static inline void rmv_page_order(struct page *page)
{
341
	__ClearPageBuddy(page);
342
	set_page_private(page, 0);
Linus Torvalds's avatar
Linus Torvalds committed
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
}

/*
 * Locate the struct page for both the matching buddy in our
 * pair (buddy1) and the combined O(n+1) page they form (page).
 *
 * 1) Any buddy B1 will have an order O twin B2 which satisfies
 * the following equation:
 *     B2 = B1 ^ (1 << O)
 * For example, if the starting buddy (buddy2) is #8 its order
 * 1 buddy is #10:
 *     B2 = 8 ^ (1 << 1) = 8 ^ 2 = 10
 *
 * 2) Any buddy B will have an order O+1 parent P which
 * satisfies the following equation:
 *     P = B & ~(1 << O)
 *
Andreas Mohr's avatar
Andreas Mohr committed
360
 * Assumption: *_mem_map is contiguous at least up to MAX_ORDER
Linus Torvalds's avatar
Linus Torvalds committed
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
 */
static inline struct page *
__page_find_buddy(struct page *page, unsigned long page_idx, unsigned int order)
{
	unsigned long buddy_idx = page_idx ^ (1 << order);

	return page + (buddy_idx - page_idx);
}

static inline unsigned long
__find_combined_index(unsigned long page_idx, unsigned int order)
{
	return (page_idx & ~(1 << order));
}

/*
 * This function checks whether a page is free && is the buddy
 * we can do coalesce a page and its buddy if
Nick Piggin's avatar
Nick Piggin committed
379
 * (a) the buddy is not in a hole &&
380
 * (b) the buddy is in the buddy system &&
381
382
 * (c) a page and its buddy have the same order &&
 * (d) a page and its buddy are in the same zone.
383
384
385
 *
 * For recording whether a page is in the buddy system, we use PG_buddy.
 * Setting, clearing, and testing PG_buddy is serialized by zone->lock.
Linus Torvalds's avatar
Linus Torvalds committed
386
 *
387
 * For recording page's order, we use page_private(page).
Linus Torvalds's avatar
Linus Torvalds committed
388
 */
389
390
static inline int page_is_buddy(struct page *page, struct page *buddy,
								int order)
Linus Torvalds's avatar
Linus Torvalds committed
391
{
392
	if (!pfn_valid_within(page_to_pfn(buddy)))
Nick Piggin's avatar
Nick Piggin committed
393
394
		return 0;

395
396
397
398
399
	if (page_zone_id(page) != page_zone_id(buddy))
		return 0;

	if (PageBuddy(buddy) && page_order(buddy) == order) {
		BUG_ON(page_count(buddy) != 0);
400
		return 1;
401
	}
402
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
}

/*
 * Freeing function for a buddy system allocator.
 *
 * The concept of a buddy system is to maintain direct-mapped table
 * (containing bit values) for memory blocks of various "orders".
 * The bottom level table contains the map for the smallest allocatable
 * units of memory (here, pages), and each level above it describes
 * pairs of units from the levels below, hence, "buddies".
 * At a high level, all that happens here is marking the table entry
 * at the bottom level available, and propagating the changes upward
 * as necessary, plus some accounting needed to play nicely with other
 * parts of the VM system.
 * At each level, we keep a list of pages, which are heads of continuous
418
 * free pages of length of (1 << order) and marked with PG_buddy. Page's
419
 * order is recorded in page_private(page) field.
Linus Torvalds's avatar
Linus Torvalds committed
420
421
422
423
424
425
426
427
428
 * So when we are allocating or freeing one, we can derive the state of the
 * other.  That is, if we allocate a small block, and both were   
 * free, the remainder of the region must be split into blocks.   
 * If a block is freed, and its buddy is also free, then this
 * triggers coalescing into a block of larger size.            
 *
 * -- wli
 */

Nick Piggin's avatar
Nick Piggin committed
429
static inline void __free_one_page(struct page *page,
Linus Torvalds's avatar
Linus Torvalds committed
430
431
432
433
		struct zone *zone, unsigned int order)
{
	unsigned long page_idx;
	int order_size = 1 << order;
434
	int migratetype = get_pageblock_migratetype(page);
Linus Torvalds's avatar
Linus Torvalds committed
435

436
	if (unlikely(PageCompound(page)))
437
438
		if (unlikely(destroy_compound_page(page, order)))
			return;
Linus Torvalds's avatar
Linus Torvalds committed
439
440
441

	page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);

Nick Piggin's avatar
Nick Piggin committed
442
443
	VM_BUG_ON(page_idx & (order_size - 1));
	VM_BUG_ON(bad_range(zone, page));
Linus Torvalds's avatar
Linus Torvalds committed
444

445
	__mod_zone_page_state(zone, NR_FREE_PAGES, order_size);
Linus Torvalds's avatar
Linus Torvalds committed
446
447
448
449
450
	while (order < MAX_ORDER-1) {
		unsigned long combined_idx;
		struct page *buddy;

		buddy = __page_find_buddy(page, page_idx, order);
451
		if (!page_is_buddy(page, buddy, order))
452
			break;
Nick Piggin's avatar
Nick Piggin committed
453

454
		/* Our buddy is free, merge with it and move up one order. */
Linus Torvalds's avatar
Linus Torvalds committed
455
		list_del(&buddy->lru);
456
		zone->free_area[order].nr_free--;
Linus Torvalds's avatar
Linus Torvalds committed
457
		rmv_page_order(buddy);
Nick Piggin's avatar
Nick Piggin committed
458
		combined_idx = __find_combined_index(page_idx, order);
Linus Torvalds's avatar
Linus Torvalds committed
459
460
461
462
463
		page = page + (combined_idx - page_idx);
		page_idx = combined_idx;
		order++;
	}
	set_page_order(page, order);
464
465
	list_add(&page->lru,
		&zone->free_area[order].free_list[migratetype]);
Linus Torvalds's avatar
Linus Torvalds committed
466
467
468
	zone->free_area[order].nr_free++;
}

469
static inline int free_pages_check(struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
470
{
471
	free_page_mlock(page);
Nick Piggin's avatar
Nick Piggin committed
472
473
474
	if (unlikely(page_mapcount(page) |
		(page->mapping != NULL)  |
		(page_count(page) != 0)  |
475
		(page->flags & PAGE_FLAGS_CHECK_AT_FREE))) {
476
		bad_page(page);
477
		return 1;
478
	}
479
480
481
	if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
		page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
482
483
484
485
486
}

/*
 * Frees a list of pages. 
 * Assumes all pages on list are in same zone, and of same order.
487
 * count is the number of pages to free.
Linus Torvalds's avatar
Linus Torvalds committed
488
489
490
491
492
493
494
 *
 * If the zone was previously in an "all pages pinned" state then look to
 * see if this freeing clears that state.
 *
 * And clear the zone's pages_scanned counter, to hold off the "all pages are
 * pinned" detection logic.
 */
Nick Piggin's avatar
Nick Piggin committed
495
496
static void free_pages_bulk(struct zone *zone, int count,
					struct list_head *list, int order)
Linus Torvalds's avatar
Linus Torvalds committed
497
{
Nick Piggin's avatar
Nick Piggin committed
498
	spin_lock(&zone->lock);
499
	zone_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE);
Linus Torvalds's avatar
Linus Torvalds committed
500
	zone->pages_scanned = 0;
Nick Piggin's avatar
Nick Piggin committed
501
502
503
	while (count--) {
		struct page *page;

Nick Piggin's avatar
Nick Piggin committed
504
		VM_BUG_ON(list_empty(list));
Linus Torvalds's avatar
Linus Torvalds committed
505
		page = list_entry(list->prev, struct page, lru);
Nick Piggin's avatar
Nick Piggin committed
506
		/* have to delete it as __free_one_page list manipulates */
Linus Torvalds's avatar
Linus Torvalds committed
507
		list_del(&page->lru);
Nick Piggin's avatar
Nick Piggin committed
508
		__free_one_page(page, zone, order);
Linus Torvalds's avatar
Linus Torvalds committed
509
	}
Nick Piggin's avatar
Nick Piggin committed
510
	spin_unlock(&zone->lock);
Linus Torvalds's avatar
Linus Torvalds committed
511
512
}

Nick Piggin's avatar
Nick Piggin committed
513
static void free_one_page(struct zone *zone, struct page *page, int order)
Linus Torvalds's avatar
Linus Torvalds committed
514
{
515
	spin_lock(&zone->lock);
516
	zone_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE);
517
	zone->pages_scanned = 0;
518
	__free_one_page(page, zone, order);
519
	spin_unlock(&zone->lock);
Nick Piggin's avatar
Nick Piggin committed
520
521
522
523
524
}

static void __free_pages_ok(struct page *page, unsigned int order)
{
	unsigned long flags;
Linus Torvalds's avatar
Linus Torvalds committed
525
	int i;
526
	int bad = 0;
Linus Torvalds's avatar
Linus Torvalds committed
527
528

	for (i = 0 ; i < (1 << order) ; ++i)
529
530
		bad += free_pages_check(page + i);
	if (bad)
531
532
		return;

533
	if (!PageHighMem(page)) {
Nick Piggin's avatar
Nick Piggin committed
534
		debug_check_no_locks_freed(page_address(page),PAGE_SIZE<<order);
535
536
537
		debug_check_no_obj_freed(page_address(page),
					   PAGE_SIZE << order);
	}
Nick Piggin's avatar
Nick Piggin committed
538
	arch_free_page(page, order);
Nick Piggin's avatar
Nick Piggin committed
539
	kernel_map_pages(page, 1 << order, 0);
Nick Piggin's avatar
Nick Piggin committed
540

Nick Piggin's avatar
Nick Piggin committed
541
	local_irq_save(flags);
542
	__count_vm_events(PGFREE, 1 << order);
Nick Piggin's avatar
Nick Piggin committed
543
	free_one_page(page_zone(page), page, order);
Nick Piggin's avatar
Nick Piggin committed
544
	local_irq_restore(flags);
Linus Torvalds's avatar
Linus Torvalds committed
545
546
}

547
548
549
/*
 * permit the bootmem allocator to evade page validation on high-order frees
 */
550
void __meminit __free_pages_bootmem(struct page *page, unsigned int order)
551
552
553
554
{
	if (order == 0) {
		__ClearPageReserved(page);
		set_page_count(page, 0);
555
		set_page_refcounted(page);
Nick Piggin's avatar
Nick Piggin committed
556
		__free_page(page);
557
558
559
	} else {
		int loop;

Nick Piggin's avatar
Nick Piggin committed
560
		prefetchw(page);
561
562
563
		for (loop = 0; loop < BITS_PER_LONG; loop++) {
			struct page *p = &page[loop];

Nick Piggin's avatar
Nick Piggin committed
564
565
			if (loop + 1 < BITS_PER_LONG)
				prefetchw(p + 1);
566
567
568
569
			__ClearPageReserved(p);
			set_page_count(p, 0);
		}

570
		set_page_refcounted(page);
Nick Piggin's avatar
Nick Piggin committed
571
		__free_pages(page, order);
572
573
574
	}
}

Linus Torvalds's avatar
Linus Torvalds committed
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589

/*
 * The order of subdivision here is critical for the IO subsystem.
 * Please do not alter this order without good reasons and regression
 * testing. Specifically, as large blocks of memory are subdivided,
 * the order in which smaller blocks are delivered depends on the order
 * they're subdivided in this function. This is the primary factor
 * influencing the order in which pages are delivered to the IO
 * subsystem according to empirical testing, and this is also justified
 * by considering the behavior of a buddy system containing a single
 * large block of memory acted on by a series of small allocations.
 * This behavior is a critical factor in sglist merging's success.
 *
 * -- wli
 */
Nick Piggin's avatar
Nick Piggin committed
590
static inline void expand(struct zone *zone, struct page *page,
591
592
	int low, int high, struct free_area *area,
	int migratetype)
Linus Torvalds's avatar
Linus Torvalds committed
593
594
595
596
597
598
599
{
	unsigned long size = 1 << high;

	while (high > low) {
		area--;
		high--;
		size >>= 1;
Nick Piggin's avatar
Nick Piggin committed
600
		VM_BUG_ON(bad_range(zone, &page[size]));
601
		list_add(&page[size].lru, &area->free_list[migratetype]);
Linus Torvalds's avatar
Linus Torvalds committed
602
603
604
605
606
607
608
609
		area->nr_free++;
		set_page_order(&page[size], high);
	}
}

/*
 * This page is about to be returned from the page allocator
 */
Nick Piggin's avatar
Nick Piggin committed
610
static int prep_new_page(struct page *page, int order, gfp_t gfp_flags)
Linus Torvalds's avatar
Linus Torvalds committed
611
{
Nick Piggin's avatar
Nick Piggin committed
612
613
614
	if (unlikely(page_mapcount(page) |
		(page->mapping != NULL)  |
		(page_count(page) != 0)  |
615
		(page->flags & PAGE_FLAGS_CHECK_AT_PREP))) {
616
		bad_page(page);
617
		return 1;
618
	}
619

620
	set_page_private(page, 0);
621
	set_page_refcounted(page);
Nick Piggin's avatar
Nick Piggin committed
622
623

	arch_alloc_page(page, order);
Linus Torvalds's avatar
Linus Torvalds committed
624
	kernel_map_pages(page, 1 << order, 1);
Nick Piggin's avatar
Nick Piggin committed
625
626
627
628
629
630
631

	if (gfp_flags & __GFP_ZERO)
		prep_zero_page(page, order, gfp_flags);

	if (order && (gfp_flags & __GFP_COMP))
		prep_compound_page(page, order);

632
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
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
/*
 * Go through the free lists for the given migratetype and remove
 * the smallest available page from the freelists
 */
static struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
						int migratetype)
{
	unsigned int current_order;
	struct free_area * area;
	struct page *page;

	/* Find a page of the appropriate size in the preferred list */
	for (current_order = order; current_order < MAX_ORDER; ++current_order) {
		area = &(zone->free_area[current_order]);
		if (list_empty(&area->free_list[migratetype]))
			continue;

		page = list_entry(area->free_list[migratetype].next,
							struct page, lru);
		list_del(&page->lru);
		rmv_page_order(page);
		area->nr_free--;
		__mod_zone_page_state(zone, NR_FREE_PAGES, - (1UL << order));
		expand(zone, page, order, current_order, area, migratetype);
		return page;
	}

	return NULL;
}


666
667
668
669
670
/*
 * This array describes the order lists are fallen back to when
 * the free lists for the desirable migrate type are depleted
 */
static int fallbacks[MIGRATE_TYPES][MIGRATE_TYPES-1] = {
671
672
673
674
	[MIGRATE_UNMOVABLE]   = { MIGRATE_RECLAIMABLE, MIGRATE_MOVABLE,   MIGRATE_RESERVE },
	[MIGRATE_RECLAIMABLE] = { MIGRATE_UNMOVABLE,   MIGRATE_MOVABLE,   MIGRATE_RESERVE },
	[MIGRATE_MOVABLE]     = { MIGRATE_RECLAIMABLE, MIGRATE_UNMOVABLE, MIGRATE_RESERVE },
	[MIGRATE_RESERVE]     = { MIGRATE_RESERVE,     MIGRATE_RESERVE,   MIGRATE_RESERVE }, /* Never used */
675
676
};

677
678
/*
 * Move the free pages in a range to the free lists of the requested type.
679
 * Note that start_page and end_pages are not aligned on a pageblock
680
681
 * boundary. If alignment is required, use move_freepages_block()
 */
Adrian Bunk's avatar
Adrian Bunk committed
682
683
684
static int move_freepages(struct zone *zone,
			  struct page *start_page, struct page *end_page,
			  int migratetype)
685
686
687
{
	struct page *page;
	unsigned long order;
688
	int pages_moved = 0;
689
690
691
692
693
694
695

#ifndef CONFIG_HOLES_IN_ZONE
	/*
	 * page_zone is not safe to call in this context when
	 * CONFIG_HOLES_IN_ZONE is set. This bug check is probably redundant
	 * anyway as we check zone boundaries in move_freepages_block().
	 * Remove at a later date when no bug reports exist related to
Mel Gorman's avatar
Mel Gorman committed
696
	 * grouping pages by mobility
697
698
699
700
701
	 */
	BUG_ON(page_zone(start_page) != page_zone(end_page));
#endif

	for (page = start_page; page <= end_page;) {
702
703
704
		/* Make sure we are not inadvertently changing nodes */
		VM_BUG_ON(page_to_nid(page) != zone_to_nid(zone));

705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
		if (!pfn_valid_within(page_to_pfn(page))) {
			page++;
			continue;
		}

		if (!PageBuddy(page)) {
			page++;
			continue;
		}

		order = page_order(page);
		list_del(&page->lru);
		list_add(&page->lru,
			&zone->free_area[order].free_list[migratetype]);
		page += 1 << order;
720
		pages_moved += 1 << order;
721
722
	}

723
	return pages_moved;
724
725
}

Adrian Bunk's avatar
Adrian Bunk committed
726
727
static int move_freepages_block(struct zone *zone, struct page *page,
				int migratetype)
728
729
730
731
732
{
	unsigned long start_pfn, end_pfn;
	struct page *start_page, *end_page;

	start_pfn = page_to_pfn(page);
733
	start_pfn = start_pfn & ~(pageblock_nr_pages-1);
734
	start_page = pfn_to_page(start_pfn);
735
736
	end_page = start_page + pageblock_nr_pages - 1;
	end_pfn = start_pfn + pageblock_nr_pages - 1;
737
738
739
740
741
742
743
744
745
746

	/* Do not cross zone boundaries */
	if (start_pfn < zone->zone_start_pfn)
		start_page = page;
	if (end_pfn >= zone->zone_start_pfn + zone->spanned_pages)
		return 0;

	return move_freepages(zone, start_page, end_page, migratetype);
}

747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
/* Remove an element from the buddy allocator from the fallback list */
static struct page *__rmqueue_fallback(struct zone *zone, int order,
						int start_migratetype)
{
	struct free_area * area;
	int current_order;
	struct page *page;
	int migratetype, i;

	/* Find the largest possible block of pages in the other list */
	for (current_order = MAX_ORDER-1; current_order >= order;
						--current_order) {
		for (i = 0; i < MIGRATE_TYPES - 1; i++) {
			migratetype = fallbacks[start_migratetype][i];

762
763
764
			/* MIGRATE_RESERVE handled later if necessary */
			if (migratetype == MIGRATE_RESERVE)
				continue;
765

766
767
768
769
770
771
772
773
774
			area = &(zone->free_area[current_order]);
			if (list_empty(&area->free_list[migratetype]))
				continue;

			page = list_entry(area->free_list[migratetype].next,
					struct page, lru);
			area->nr_free--;

			/*
775
			 * If breaking a large block of pages, move all free
776
777
778
			 * pages to the preferred allocation list. If falling
			 * back for a reclaimable kernel allocation, be more
			 * agressive about taking ownership of free pages
779
			 */
780
			if (unlikely(current_order >= (pageblock_order >> 1)) ||
781
782
783
784
785
786
					start_migratetype == MIGRATE_RECLAIMABLE) {
				unsigned long pages;
				pages = move_freepages_block(zone, page,
								start_migratetype);

				/* Claim the whole block if over half of it is free */
787
				if (pages >= (1 << (pageblock_order-1)))
788
789
790
					set_pageblock_migratetype(page,
								start_migratetype);

791
				migratetype = start_migratetype;
792
			}
793
794
795
796
797
798
799

			/* Remove the page from the freelists */
			list_del(&page->lru);
			rmv_page_order(page);
			__mod_zone_page_state(zone, NR_FREE_PAGES,
							-(1UL << order));

800
			if (current_order == pageblock_order)
801
802
803
804
805
806
807
808
				set_pageblock_migratetype(page,
							start_migratetype);

			expand(zone, page, order, current_order, area, migratetype);
			return page;
		}
	}

809
810
	/* Use MIGRATE_RESERVE rather than fail an allocation */
	return __rmqueue_smallest(zone, order, MIGRATE_RESERVE);
811
812
}

813
/*
Linus Torvalds's avatar
Linus Torvalds committed
814
815
816
 * Do the hard work of removing an element from the buddy allocator.
 * Call me with the zone->lock already held.
 */
817
818
static struct page *__rmqueue(struct zone *zone, unsigned int order,
						int migratetype)
Linus Torvalds's avatar
Linus Torvalds committed
819
820
821
{
	struct page *page;

822
	page = __rmqueue_smallest(zone, order, migratetype);
823

824
825
	if (unlikely(!page))
		page = __rmqueue_fallback(zone, order, migratetype);
826
827

	return page;
Linus Torvalds's avatar
Linus Torvalds committed
828
829
830
831
832
833
834
835
}

/* 
 * Obtain a specified number of elements from the buddy allocator, all under
 * a single hold of the lock, for efficiency.  Add them to the supplied list.
 * Returns the number of new pages which were placed at *list.
 */
static int rmqueue_bulk(struct zone *zone, unsigned int order, 
836
837
			unsigned long count, struct list_head *list,
			int migratetype)
Linus Torvalds's avatar
Linus Torvalds committed
838
839
840
{
	int i;
	
Nick Piggin's avatar
Nick Piggin committed
841
	spin_lock(&zone->lock);
Linus Torvalds's avatar
Linus Torvalds committed
842
	for (i = 0; i < count; ++i) {
843
		struct page *page = __rmqueue(zone, order, migratetype);
Nick Piggin's avatar
Nick Piggin committed
844
		if (unlikely(page == NULL))
Linus Torvalds's avatar
Linus Torvalds committed
845
			break;
846
847
848
849
850
851
852
853
854
855

		/*
		 * Split buddy pages returned by expand() are received here
		 * in physical page order. The page is added to the callers and
		 * list and the list head then moves forward. From the callers
		 * perspective, the linked list is ordered by page number in
		 * some conditions. This is useful for IO devices that can
		 * merge IO requests if the physical pages are ordered
		 * properly.
		 */
856
857
		list_add(&page->lru, list);
		set_page_private(page, migratetype);
858
		list = &page->lru;
Linus Torvalds's avatar
Linus Torvalds committed
859
	}
Nick Piggin's avatar
Nick Piggin committed
860
	spin_unlock(&zone->lock);
Nick Piggin's avatar
Nick Piggin committed
861
	return i;
Linus Torvalds's avatar
Linus Torvalds committed
862
863
}

864
#ifdef CONFIG_NUMA
865
/*
866
867
868
869
 * Called from the vmstat counter updater to drain pagesets of this
 * currently executing processor on remote nodes after they have
 * expired.
 *
870
871
 * Note that this function must be called with the thread pinned to
 * a single processor.
872
 */
873
void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
874
875
{
	unsigned long flags;
876
	int to_drain;
877

878
879
880
881
882
883
884
885
	local_irq_save(flags);
	if (pcp->count >= pcp->batch)
		to_drain = pcp->batch;
	else
		to_drain = pcp->count;
	free_pages_bulk(zone, to_drain, &pcp->list, 0);
	pcp->count -= to_drain;
	local_irq_restore(flags);
886
887
888
}
#endif

889
890
891
892
893
894
895
896
/*
 * Drain pages of the indicated processor.
 *
 * The processor must either be the current processor and the
 * thread pinned to the current processor or a processor that
 * is not online.
 */
static void drain_pages(unsigned int cpu)
Linus Torvalds's avatar
Linus Torvalds committed
897
{
Nick Piggin's avatar
Nick Piggin committed
898
	unsigned long flags;
Linus Torvalds's avatar
Linus Torvalds committed
899
900
901
902
	struct zone *zone;

	for_each_zone(zone) {
		struct per_cpu_pageset *pset;
903
		struct per_cpu_pages *pcp;
Linus Torvalds's avatar
Linus Torvalds committed
904

905
906
907
		if (!populated_zone(zone))
			continue;

908
		pset = zone_pcp(zone, cpu);
909
910
911
912
913
914

		pcp = &pset->pcp;
		local_irq_save(flags);
		free_pages_bulk(zone, pcp->count, &pcp->list, 0);
		pcp->count = 0;
		local_irq_restore(flags);
Linus Torvalds's avatar
Linus Torvalds committed
915
916
917
	}
}

918
919
920
921
922
923
924
925
926
927
928
929
930
/*
 * Spill all of this CPU's per-cpu pages back into the buddy allocator.
 */
void drain_local_pages(void *arg)
{
	drain_pages(smp_processor_id());
}

/*
 * Spill all the per-cpu pages from all CPUs back into the buddy allocator
 */
void drain_all_pages(void)
{
931
	on_each_cpu(drain_local_pages, NULL, 1);
932
933
}

934
#ifdef CONFIG_HIBERNATION
Linus Torvalds's avatar
Linus Torvalds committed
935
936
937

void mark_free_pages(struct zone *zone)
{
938
939
	unsigned long pfn, max_zone_pfn;
	unsigned long flags;
940
	int order, t;
Linus Torvalds's avatar
Linus Torvalds committed
941
942
943
944
945
946
	struct list_head *curr;

	if (!zone->spanned_pages)
		return;

	spin_lock_irqsave(&zone->lock, flags);
947
948
949
950
951
952

	max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
	for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
		if (pfn_valid(pfn)) {
			struct page *page = pfn_to_page(pfn);

953
954
			if (!swsusp_page_is_forbidden(page))
				swsusp_unset_page_free(page);
955
		}
Linus Torvalds's avatar
Linus Torvalds committed
956

957
958
	for_each_migratetype_order(order, t) {
		list_for_each(curr, &zone->free_area[order].free_list[t]) {
959
			unsigned long i;
Linus Torvalds's avatar
Linus Torvalds committed
960

961
962
			pfn = page_to_pfn(list_entry(curr, struct page, lru));
			for (i = 0; i < (1UL << order); i++)
963
				swsusp_set_page_free(pfn_to_page(pfn + i));
964
		}
965
	}
Linus Torvalds's avatar
Linus Torvalds committed
966
967
	spin_unlock_irqrestore(&zone->lock, flags);
}
968
#endif /* CONFIG_PM */
Linus Torvalds's avatar
Linus Torvalds committed
969
970
971
972

/*
 * Free a 0-order page
 */
Harvey Harrison's avatar
Harvey Harrison committed
973
static void free_hot_cold_page(struct page *page, int cold)
Linus Torvalds's avatar
Linus Torvalds committed
974
975
976
977
978
979
980
{
	struct zone *zone = page_zone(page);
	struct per_cpu_pages *pcp;
	unsigned long flags;

	if (PageAnon(page))
		page->mapping = NULL;
981
	if (free_pages_check(page))
982
983
		return;

984
	if (!PageHighMem(page)) {
Nick Piggin's avatar
Nick Piggin committed
985
		debug_check_no_locks_freed(page_address(page), PAGE_SIZE);
986
987
		debug_check_no_obj_freed(page_address(page), PAGE_SIZE);
	}
Nick Piggin's avatar
Nick Piggin committed
988
	arch_free_page(page, 0);
989
990
	kernel_map_pages(page, 1, 0);

991
	pcp = &zone_pcp(zone, get_cpu())->pcp;
Linus Torvalds's avatar
Linus Torvalds committed
992
	local_irq_save(flags);
993
	__count_vm_event(PGFREE);
994
995
996
997
	if (cold)
		list_add_tail(&page->lru, &pcp->list);
	else
		list_add(&page->lru, &pcp->list);
998
	set_page_private(page, get_pageblock_migratetype(page));
Linus Torvalds's avatar
Linus Torvalds committed
999
	pcp->count++;
Nick Piggin's avatar
Nick Piggin committed
1000
1001
1002
1003
	if (pcp->count >= pcp->high) {
		free_pages_bulk(zone, pcp->batch, &pcp->list, 0);
		pcp->count -= pcp->batch;
	}
Linus Torvalds's avatar
Linus Torvalds committed
1004
1005
1006
1007
	local_irq_restore(flags);
	put_cpu();
}

Harvey Harrison's avatar
Harvey Harrison committed
1008
void free_hot_page(struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
1009
1010
1011
1012
{
	free_hot_cold_page(page, 0);
}
	
Harvey Harrison's avatar
Harvey Harrison committed
1013
void free_cold_page(struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
1014
1015
1016
1017
{
	free_hot_cold_page(page, 1);
}

1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
/*
 * split_page takes a non-compound higher-order page, and splits it into
 * n (1<<order) sub-pages: page[0..n]
 * Each sub-page must be freed individually.
 *
 * Note: this is probably too low level an operation for use in drivers.
 * Please consult with lkml before using this in your driver.
 */
void split_page(struct page *page, unsigned int order)
{
	int i;

Nick Piggin's avatar
Nick Piggin committed
1030
1031
	VM_BUG_ON(PageCompound(page));
	VM_BUG_ON(!page_count(page));
1032
1033
	for (i = 1; i < (1 << order); i++)
		set_page_refcounted(page + i);
1034
1035
}

Linus Torvalds's avatar
Linus Torvalds committed
1036
1037
1038
1039
1040
/*
 * Really, prep_compound_page() should be called from __rmqueue_bulk().  But
 * we cheat by calling it from here, in the order > 0 path.  Saves a branch
 * or two.
 */
1041
static struct page *buffered_rmqueue(struct zone *preferred_zone,
Nick Piggin's avatar
Nick Piggin committed
1042
			struct zone *zone, int order, gfp_t gfp_flags)
Linus Torvalds's avatar
Linus Torvalds committed
1043
1044
{
	unsigned long flags;
1045
	struct page *page;
Linus Torvalds's avatar
Linus Torvalds committed
1046
	int cold = !!(gfp_flags & __GFP_COLD);
Nick Piggin's avatar
Nick Piggin committed
1047
	int cpu;
1048
	int migratetype = allocflags_to_migratetype(gfp_flags);
Linus Torvalds's avatar
Linus Torvalds committed
1049

1050
again:
Nick Piggin's avatar
Nick Piggin committed
1051
	cpu  = get_cpu();
Nick Piggin's avatar
Nick Piggin committed
1052
	if (likely(order == 0)) {
Linus Torvalds's avatar
Linus Torvalds committed
1053
1054
		struct per_cpu_pages *pcp;

1055
		pcp = &zone_pcp(zone, cpu)->pcp;
Linus Torvalds's avatar
Linus Torvalds committed
1056
		local_irq_save(flags);
Nick Piggin's avatar
Nick Piggin committed
1057
		if (!pcp->count) {
1058
			pcp->count = rmqueue_bulk(zone, 0,
1059
					pcp->batch, &pcp->list, migratetype);
Nick Piggin's avatar
Nick Piggin committed
1060
1061
			if (unlikely(!pcp->count))
				goto failed;