page_alloc.c 106 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
22
23
/*
 *  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>
#include <linux/bootmem.h>
#include <linux/compiler.h>
24
#include <linux/kernel.h>
Linus Torvalds's avatar
Linus Torvalds committed
25
26
27
28
29
30
31
32
33
34
#include <linux/module.h>
#include <linux/suspend.h>
#include <linux/pagevec.h>
#include <linux/blkdev.h>
#include <linux/slab.h>
#include <linux/notifier.h>
#include <linux/topology.h>
#include <linux/sysctl.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
35
#include <linux/memory_hotplug.h>
Linus Torvalds's avatar
Linus Torvalds committed
36
37
#include <linux/nodemask.h>
#include <linux/vmalloc.h>
38
#include <linux/mempolicy.h>
39
#include <linux/stop_machine.h>
40
41
#include <linux/sort.h>
#include <linux/pfn.h>
42
#include <linux/backing-dev.h>
43
#include <linux/fault-inject.h>
Linus Torvalds's avatar
Linus Torvalds committed
44
45

#include <asm/tlbflush.h>
46
#include <asm/div64.h>
Linus Torvalds's avatar
Linus Torvalds committed
47
48
49
50
51
52
#include "internal.h"

/*
 * MCD - HACK: Find somewhere to initialize this EARLY, or make this
 * initializer cleaner
 */
53
nodemask_t node_online_map __read_mostly = { { [0] = 1UL } };
54
EXPORT_SYMBOL(node_online_map);
55
nodemask_t node_possible_map __read_mostly = NODE_MASK_ALL;
56
EXPORT_SYMBOL(node_possible_map);
57
unsigned long totalram_pages __read_mostly;
58
unsigned long totalreserve_pages __read_mostly;
Linus Torvalds's avatar
Linus Torvalds committed
59
long nr_swap_pages;
60
int percpu_pagelist_fraction;
Linus Torvalds's avatar
Linus Torvalds committed
61

62
static void __free_pages_ok(struct page *page, unsigned int order);
63

Linus Torvalds's avatar
Linus Torvalds committed
64
65
66
67
68
69
70
/*
 * 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
71
72
73
 *
 * 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
74
 */
75
int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
76
#ifdef CONFIG_ZONE_DMA
77
	 256,
78
#endif
79
#ifdef CONFIG_ZONE_DMA32
80
	 256,
81
#endif
82
#ifdef CONFIG_HIGHMEM
Mel Gorman's avatar
Mel Gorman committed
83
	 32,
84
#endif
Mel Gorman's avatar
Mel Gorman committed
85
	 32,
86
};
Linus Torvalds's avatar
Linus Torvalds committed
87
88
89

EXPORT_SYMBOL(totalram_pages);

90
static char * const zone_names[MAX_NR_ZONES] = {
91
#ifdef CONFIG_ZONE_DMA
92
	 "DMA",
93
#endif
94
#ifdef CONFIG_ZONE_DMA32
95
	 "DMA32",
96
#endif
97
	 "Normal",
98
#ifdef CONFIG_HIGHMEM
Mel Gorman's avatar
Mel Gorman committed
99
	 "HighMem",
100
#endif
Mel Gorman's avatar
Mel Gorman committed
101
	 "Movable",
102
103
};

Linus Torvalds's avatar
Linus Torvalds committed
104
105
int min_free_kbytes = 1024;

106
107
unsigned long __meminitdata nr_kernel_pages;
unsigned long __meminitdata nr_all_pages;
108
static unsigned long __meminitdata dma_reserve;
Linus Torvalds's avatar
Linus Torvalds committed
109

110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
#ifdef CONFIG_ARCH_POPULATES_NODE_MAP
  /*
   * MAX_ACTIVE_REGIONS determines the maxmimum number of distinct
   * 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

131
132
133
134
  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];
135
#ifdef CONFIG_MEMORY_HOTPLUG_RESERVE
136
137
  static unsigned long __meminitdata node_boundary_start_pfn[MAX_NUMNODES];
  static unsigned long __meminitdata node_boundary_end_pfn[MAX_NUMNODES];
138
#endif /* CONFIG_MEMORY_HOTPLUG_RESERVE */
Mel Gorman's avatar
Mel Gorman committed
139
  unsigned long __initdata required_kernelcore;
140
  unsigned long __initdata required_movablecore;
Mel Gorman's avatar
Mel Gorman committed
141
142
143
144
145
  unsigned long __initdata zone_movable_pfn[MAX_NUMNODES];

  /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
  int movable_zone;
  EXPORT_SYMBOL(movable_zone);
146
147
#endif /* CONFIG_ARCH_POPULATES_NODE_MAP */

Miklos Szeredi's avatar
Miklos Szeredi committed
148
149
150
151
152
#if MAX_NUMNODES > 1
int nr_node_ids __read_mostly = MAX_NUMNODES;
EXPORT_SYMBOL(nr_node_ids);
#endif

Nick Piggin's avatar
Nick Piggin committed
153
#ifdef CONFIG_DEBUG_VM
154
static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
155
{
156
157
158
	int ret = 0;
	unsigned seq;
	unsigned long pfn = page_to_pfn(page);
159

160
161
162
163
164
165
166
167
168
	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;
169
170
171
172
}

static int page_is_consistent(struct zone *zone, struct page *page)
{
173
	if (!pfn_valid_within(page_to_pfn(page)))
174
		return 0;
Linus Torvalds's avatar
Linus Torvalds committed
175
	if (zone != page_zone(page))
176
177
178
179
180
181
182
183
184
185
		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
186
		return 1;
187
188
189
	if (!page_is_consistent(zone, page))
		return 1;

Linus Torvalds's avatar
Linus Torvalds committed
190
191
	return 0;
}
Nick Piggin's avatar
Nick Piggin committed
192
193
194
195
196
197
198
#else
static inline int bad_range(struct zone *zone, struct page *page)
{
	return 0;
}
#endif

199
static void bad_page(struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
200
{
201
	printk(KERN_EMERG "Bad page state in process '%s'\n"
202
203
204
		KERN_EMERG "page:%p flags:0x%0*lx mapping:%p mapcount:%d count:%d\n"
		KERN_EMERG "Trying to fix it up, but a reboot is needed\n"
		KERN_EMERG "Backtrace:\n",
205
206
207
		current->comm, page, (int)(2*sizeof(unsigned long)),
		(unsigned long)page->flags, page->mapping,
		page_mapcount(page), page_count(page));
Linus Torvalds's avatar
Linus Torvalds committed
208
	dump_stack();
209
210
	page->flags &= ~(1 << PG_lru	|
			1 << PG_private |
Linus Torvalds's avatar
Linus Torvalds committed
211
212
213
			1 << PG_locked	|
			1 << PG_active	|
			1 << PG_dirty	|
214
215
			1 << PG_reclaim |
			1 << PG_slab    |
Linus Torvalds's avatar
Linus Torvalds committed
216
			1 << PG_swapcache |
217
218
			1 << PG_writeback |
			1 << PG_buddy );
Linus Torvalds's avatar
Linus Torvalds committed
219
220
221
	set_page_count(page, 0);
	reset_page_mapcount(page);
	page->mapping = NULL;
222
	add_taint(TAINT_BAD_PAGE);
Linus Torvalds's avatar
Linus Torvalds committed
223
224
225
226
227
228
229
230
231
232
233
234
}

/*
 * 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).
 *
235
236
237
 * 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
238
 */
239
240
241

static void free_compound_page(struct page *page)
{
242
	__free_pages_ok(page, compound_order(page));
243
244
}

Linus Torvalds's avatar
Linus Torvalds committed
245
246
247
248
249
static void prep_compound_page(struct page *page, unsigned long order)
{
	int i;
	int nr_pages = 1 << order;

250
	set_compound_page_dtor(page, free_compound_page);
251
	set_compound_order(page, order);
252
	__SetPageHead(page);
253
	for (i = 1; i < nr_pages; i++) {
Linus Torvalds's avatar
Linus Torvalds committed
254
255
		struct page *p = page + i;

256
257
		__SetPageTail(p);
		p->first_page = page;
Linus Torvalds's avatar
Linus Torvalds committed
258
259
260
261
262
263
264
265
	}
}

static void destroy_compound_page(struct page *page, unsigned long order)
{
	int i;
	int nr_pages = 1 << order;

266
	if (unlikely(compound_order(page) != order))
267
		bad_page(page);
Linus Torvalds's avatar
Linus Torvalds committed
268

269
	if (unlikely(!PageHead(page)))
270
			bad_page(page);
271
	__ClearPageHead(page);
272
	for (i = 1; i < nr_pages; i++) {
Linus Torvalds's avatar
Linus Torvalds committed
273
274
		struct page *p = page + i;

275
		if (unlikely(!PageTail(p) |
276
				(p->first_page != page)))
277
			bad_page(page);
278
		__ClearPageTail(p);
Linus Torvalds's avatar
Linus Torvalds committed
279
280
281
	}
}

Nick Piggin's avatar
Nick Piggin committed
282
283
284
285
static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags)
{
	int i;

Nick Piggin's avatar
Nick Piggin committed
286
	VM_BUG_ON((gfp_flags & (__GFP_WAIT | __GFP_HIGHMEM)) == __GFP_HIGHMEM);
287
288
289
290
	/*
	 * 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
291
	VM_BUG_ON((gfp_flags & __GFP_HIGHMEM) && in_interrupt());
Nick Piggin's avatar
Nick Piggin committed
292
293
294
295
	for (i = 0; i < (1 << order); i++)
		clear_highpage(page + i);
}

Linus Torvalds's avatar
Linus Torvalds committed
296
297
298
299
300
/*
 * function for dealing with page's order in buddy system.
 * zone->lock is already acquired when we use these.
 * So, we don't need atomic page->flags operations here.
 */
301
302
static inline unsigned long page_order(struct page *page)
{
303
	return page_private(page);
Linus Torvalds's avatar
Linus Torvalds committed
304
305
}

306
307
static inline void set_page_order(struct page *page, int order)
{
308
	set_page_private(page, order);
309
	__SetPageBuddy(page);
Linus Torvalds's avatar
Linus Torvalds committed
310
311
312
313
}

static inline void rmv_page_order(struct page *page)
{
314
	__ClearPageBuddy(page);
315
	set_page_private(page, 0);
Linus Torvalds's avatar
Linus Torvalds committed
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
}

/*
 * 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
333
 * Assumption: *_mem_map is contiguous at least up to MAX_ORDER
Linus Torvalds's avatar
Linus Torvalds committed
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
 */
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
352
 * (a) the buddy is not in a hole &&
353
 * (b) the buddy is in the buddy system &&
354
355
 * (c) a page and its buddy have the same order &&
 * (d) a page and its buddy are in the same zone.
356
357
358
 *
 * 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
359
 *
360
 * For recording page's order, we use page_private(page).
Linus Torvalds's avatar
Linus Torvalds committed
361
 */
362
363
static inline int page_is_buddy(struct page *page, struct page *buddy,
								int order)
Linus Torvalds's avatar
Linus Torvalds committed
364
{
365
	if (!pfn_valid_within(page_to_pfn(buddy)))
Nick Piggin's avatar
Nick Piggin committed
366
367
		return 0;

368
369
370
371
372
	if (page_zone_id(page) != page_zone_id(buddy))
		return 0;

	if (PageBuddy(buddy) && page_order(buddy) == order) {
		BUG_ON(page_count(buddy) != 0);
373
		return 1;
374
	}
375
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
}

/*
 * 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
391
 * free pages of length of (1 << order) and marked with PG_buddy. Page's
392
 * order is recorded in page_private(page) field.
Linus Torvalds's avatar
Linus Torvalds committed
393
394
395
396
397
398
399
400
401
 * 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
402
static inline void __free_one_page(struct page *page,
Linus Torvalds's avatar
Linus Torvalds committed
403
404
405
406
407
		struct zone *zone, unsigned int order)
{
	unsigned long page_idx;
	int order_size = 1 << order;

408
	if (unlikely(PageCompound(page)))
Linus Torvalds's avatar
Linus Torvalds committed
409
410
411
412
		destroy_compound_page(page, order);

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

Nick Piggin's avatar
Nick Piggin committed
413
414
	VM_BUG_ON(page_idx & (order_size - 1));
	VM_BUG_ON(bad_range(zone, page));
Linus Torvalds's avatar
Linus Torvalds committed
415

416
	__mod_zone_page_state(zone, NR_FREE_PAGES, order_size);
Linus Torvalds's avatar
Linus Torvalds committed
417
418
419
420
421
422
	while (order < MAX_ORDER-1) {
		unsigned long combined_idx;
		struct free_area *area;
		struct page *buddy;

		buddy = __page_find_buddy(page, page_idx, order);
423
		if (!page_is_buddy(page, buddy, order))
Linus Torvalds's avatar
Linus Torvalds committed
424
			break;		/* Move the buddy up one level. */
Nick Piggin's avatar
Nick Piggin committed
425

Linus Torvalds's avatar
Linus Torvalds committed
426
427
428
429
		list_del(&buddy->lru);
		area = zone->free_area + order;
		area->nr_free--;
		rmv_page_order(buddy);
Nick Piggin's avatar
Nick Piggin committed
430
		combined_idx = __find_combined_index(page_idx, order);
Linus Torvalds's avatar
Linus Torvalds committed
431
432
433
434
435
436
437
438
439
		page = page + (combined_idx - page_idx);
		page_idx = combined_idx;
		order++;
	}
	set_page_order(page, order);
	list_add(&page->lru, &zone->free_area[order].free_list);
	zone->free_area[order].nr_free++;
}

440
static inline int free_pages_check(struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
441
{
Nick Piggin's avatar
Nick Piggin committed
442
443
444
	if (unlikely(page_mapcount(page) |
		(page->mapping != NULL)  |
		(page_count(page) != 0)  |
Linus Torvalds's avatar
Linus Torvalds committed
445
446
447
448
449
450
451
		(page->flags & (
			1 << PG_lru	|
			1 << PG_private |
			1 << PG_locked	|
			1 << PG_active	|
			1 << PG_slab	|
			1 << PG_swapcache |
Nick Piggin's avatar
Nick Piggin committed
452
			1 << PG_writeback |
453
454
			1 << PG_reserved |
			1 << PG_buddy ))))
455
		bad_page(page);
456
457
458
459
460
461
	/*
	 * PageReclaim == PageTail. It is only an error
	 * for PageReclaim to be set if PageCompound is clear.
	 */
	if (unlikely(!PageCompound(page) && PageReclaim(page)))
		bad_page(page);
Linus Torvalds's avatar
Linus Torvalds committed
462
	if (PageDirty(page))
Nick Piggin's avatar
Nick Piggin committed
463
		__ClearPageDirty(page);
464
465
466
467
468
469
	/*
	 * For now, we report if PG_reserved was found set, but do not
	 * clear it, and do not free the page.  But we shall soon need
	 * to do more, for when the ZERO_PAGE count wraps negative.
	 */
	return PageReserved(page);
Linus Torvalds's avatar
Linus Torvalds committed
470
471
472
473
474
}

/*
 * Frees a list of pages. 
 * Assumes all pages on list are in same zone, and of same order.
475
 * count is the number of pages to free.
Linus Torvalds's avatar
Linus Torvalds committed
476
477
478
479
480
481
482
 *
 * 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
483
484
static void free_pages_bulk(struct zone *zone, int count,
					struct list_head *list, int order)
Linus Torvalds's avatar
Linus Torvalds committed
485
{
Nick Piggin's avatar
Nick Piggin committed
486
	spin_lock(&zone->lock);
Linus Torvalds's avatar
Linus Torvalds committed
487
488
	zone->all_unreclaimable = 0;
	zone->pages_scanned = 0;
Nick Piggin's avatar
Nick Piggin committed
489
490
491
	while (count--) {
		struct page *page;

Nick Piggin's avatar
Nick Piggin committed
492
		VM_BUG_ON(list_empty(list));
Linus Torvalds's avatar
Linus Torvalds committed
493
		page = list_entry(list->prev, struct page, lru);
Nick Piggin's avatar
Nick Piggin committed
494
		/* have to delete it as __free_one_page list manipulates */
Linus Torvalds's avatar
Linus Torvalds committed
495
		list_del(&page->lru);
Nick Piggin's avatar
Nick Piggin committed
496
		__free_one_page(page, zone, order);
Linus Torvalds's avatar
Linus Torvalds committed
497
	}
Nick Piggin's avatar
Nick Piggin committed
498
	spin_unlock(&zone->lock);
Linus Torvalds's avatar
Linus Torvalds committed
499
500
}

Nick Piggin's avatar
Nick Piggin committed
501
static void free_one_page(struct zone *zone, struct page *page, int order)
Linus Torvalds's avatar
Linus Torvalds committed
502
{
503
504
505
	spin_lock(&zone->lock);
	zone->all_unreclaimable = 0;
	zone->pages_scanned = 0;
506
	__free_one_page(page, zone, order);
507
	spin_unlock(&zone->lock);
Nick Piggin's avatar
Nick Piggin committed
508
509
510
511
512
}

static void __free_pages_ok(struct page *page, unsigned int order)
{
	unsigned long flags;
Linus Torvalds's avatar
Linus Torvalds committed
513
	int i;
514
	int reserved = 0;
Linus Torvalds's avatar
Linus Torvalds committed
515
516

	for (i = 0 ; i < (1 << order) ; ++i)
517
		reserved += free_pages_check(page + i);
518
519
520
	if (reserved)
		return;

Nick Piggin's avatar
Nick Piggin committed
521
522
	if (!PageHighMem(page))
		debug_check_no_locks_freed(page_address(page),PAGE_SIZE<<order);
Nick Piggin's avatar
Nick Piggin committed
523
	arch_free_page(page, order);
Nick Piggin's avatar
Nick Piggin committed
524
	kernel_map_pages(page, 1 << order, 0);
Nick Piggin's avatar
Nick Piggin committed
525

Nick Piggin's avatar
Nick Piggin committed
526
	local_irq_save(flags);
527
	__count_vm_events(PGFREE, 1 << order);
Nick Piggin's avatar
Nick Piggin committed
528
	free_one_page(page_zone(page), page, order);
Nick Piggin's avatar
Nick Piggin committed
529
	local_irq_restore(flags);
Linus Torvalds's avatar
Linus Torvalds committed
530
531
}

532
533
534
535
536
537
538
539
/*
 * permit the bootmem allocator to evade page validation on high-order frees
 */
void fastcall __init __free_pages_bootmem(struct page *page, unsigned int order)
{
	if (order == 0) {
		__ClearPageReserved(page);
		set_page_count(page, 0);
540
		set_page_refcounted(page);
Nick Piggin's avatar
Nick Piggin committed
541
		__free_page(page);
542
543
544
	} else {
		int loop;

Nick Piggin's avatar
Nick Piggin committed
545
		prefetchw(page);
546
547
548
		for (loop = 0; loop < BITS_PER_LONG; loop++) {
			struct page *p = &page[loop];

Nick Piggin's avatar
Nick Piggin committed
549
550
			if (loop + 1 < BITS_PER_LONG)
				prefetchw(p + 1);
551
552
553
554
			__ClearPageReserved(p);
			set_page_count(p, 0);
		}

555
		set_page_refcounted(page);
Nick Piggin's avatar
Nick Piggin committed
556
		__free_pages(page, order);
557
558
559
	}
}

Linus Torvalds's avatar
Linus Torvalds committed
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574

/*
 * 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
575
static inline void expand(struct zone *zone, struct page *page,
Linus Torvalds's avatar
Linus Torvalds committed
576
577
578
579
580
581
582
583
 	int low, int high, struct free_area *area)
{
	unsigned long size = 1 << high;

	while (high > low) {
		area--;
		high--;
		size >>= 1;
Nick Piggin's avatar
Nick Piggin committed
584
		VM_BUG_ON(bad_range(zone, &page[size]));
Linus Torvalds's avatar
Linus Torvalds committed
585
586
587
588
589
590
591
592
593
		list_add(&page[size].lru, &area->free_list);
		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
594
static int prep_new_page(struct page *page, int order, gfp_t gfp_flags)
Linus Torvalds's avatar
Linus Torvalds committed
595
{
Nick Piggin's avatar
Nick Piggin committed
596
597
598
	if (unlikely(page_mapcount(page) |
		(page->mapping != NULL)  |
		(page_count(page) != 0)  |
599
600
		(page->flags & (
			1 << PG_lru	|
Linus Torvalds's avatar
Linus Torvalds committed
601
602
603
604
605
			1 << PG_private	|
			1 << PG_locked	|
			1 << PG_active	|
			1 << PG_dirty	|
			1 << PG_reclaim	|
606
			1 << PG_slab    |
Linus Torvalds's avatar
Linus Torvalds committed
607
			1 << PG_swapcache |
Nick Piggin's avatar
Nick Piggin committed
608
			1 << PG_writeback |
609
610
			1 << PG_reserved |
			1 << PG_buddy ))))
611
		bad_page(page);
Linus Torvalds's avatar
Linus Torvalds committed
612

613
614
615
616
617
618
619
	/*
	 * For now, we report if PG_reserved was found set, but do not
	 * clear it, and do not allocate the page: as a safety net.
	 */
	if (PageReserved(page))
		return 1;

Linus Torvalds's avatar
Linus Torvalds committed
620
621
	page->flags &= ~(1 << PG_uptodate | 1 << PG_error |
			1 << PG_referenced | 1 << PG_arch_1 |
622
			1 << PG_owner_priv_1 | 1 << PG_mappedtodisk);
623
	set_page_private(page, 0);
624
	set_page_refcounted(page);
Nick Piggin's avatar
Nick Piggin committed
625
626

	arch_alloc_page(page, order);
Linus Torvalds's avatar
Linus Torvalds committed
627
	kernel_map_pages(page, 1 << order, 1);
Nick Piggin's avatar
Nick Piggin committed
628
629
630
631
632
633
634

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

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

635
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
}

/* 
 * Do the hard work of removing an element from the buddy allocator.
 * Call me with the zone->lock already held.
 */
static struct page *__rmqueue(struct zone *zone, unsigned int order)
{
	struct free_area * area;
	unsigned int current_order;
	struct page *page;

	for (current_order = order; current_order < MAX_ORDER; ++current_order) {
		area = zone->free_area + current_order;
		if (list_empty(&area->free_list))
			continue;

		page = list_entry(area->free_list.next, struct page, lru);
		list_del(&page->lru);
		rmv_page_order(page);
		area->nr_free--;
657
		__mod_zone_page_state(zone, NR_FREE_PAGES, - (1UL << order));
Nick Piggin's avatar
Nick Piggin committed
658
659
		expand(zone, page, order, current_order, area);
		return page;
Linus Torvalds's avatar
Linus Torvalds committed
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
	}

	return NULL;
}

/* 
 * 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, 
			unsigned long count, struct list_head *list)
{
	int i;
	
Nick Piggin's avatar
Nick Piggin committed
675
	spin_lock(&zone->lock);
Linus Torvalds's avatar
Linus Torvalds committed
676
	for (i = 0; i < count; ++i) {
Nick Piggin's avatar
Nick Piggin committed
677
678
		struct page *page = __rmqueue(zone, order);
		if (unlikely(page == NULL))
Linus Torvalds's avatar
Linus Torvalds committed
679
680
681
			break;
		list_add_tail(&page->lru, list);
	}
Nick Piggin's avatar
Nick Piggin committed
682
	spin_unlock(&zone->lock);
Nick Piggin's avatar
Nick Piggin committed
683
	return i;
Linus Torvalds's avatar
Linus Torvalds committed
684
685
}

686
#ifdef CONFIG_NUMA
687
/*
688
689
690
691
 * Called from the vmstat counter updater to drain pagesets of this
 * currently executing processor on remote nodes after they have
 * expired.
 *
692
693
 * Note that this function must be called with the thread pinned to
 * a single processor.
694
 */
695
void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
696
697
{
	unsigned long flags;
698
	int to_drain;
699

700
701
702
703
704
705
706
707
	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);
708
709
710
}
#endif

Linus Torvalds's avatar
Linus Torvalds committed
711
712
static void __drain_pages(unsigned int cpu)
{
Nick Piggin's avatar
Nick Piggin committed
713
	unsigned long flags;
Linus Torvalds's avatar
Linus Torvalds committed
714
715
716
717
718
719
	struct zone *zone;
	int i;

	for_each_zone(zone) {
		struct per_cpu_pageset *pset;

720
721
722
		if (!populated_zone(zone))
			continue;

723
		pset = zone_pcp(zone, cpu);
Linus Torvalds's avatar
Linus Torvalds committed
724
725
726
727
		for (i = 0; i < ARRAY_SIZE(pset->pcp); i++) {
			struct per_cpu_pages *pcp;

			pcp = &pset->pcp[i];
Nick Piggin's avatar
Nick Piggin committed
728
			local_irq_save(flags);
Nick Piggin's avatar
Nick Piggin committed
729
730
			free_pages_bulk(zone, pcp->count, &pcp->list, 0);
			pcp->count = 0;
Nick Piggin's avatar
Nick Piggin committed
731
			local_irq_restore(flags);
Linus Torvalds's avatar
Linus Torvalds committed
732
733
734
735
736
737
738
739
		}
	}
}

#ifdef CONFIG_PM

void mark_free_pages(struct zone *zone)
{
740
741
	unsigned long pfn, max_zone_pfn;
	unsigned long flags;
Linus Torvalds's avatar
Linus Torvalds committed
742
743
744
745
746
747
748
	int order;
	struct list_head *curr;

	if (!zone->spanned_pages)
		return;

	spin_lock_irqsave(&zone->lock, flags);
749
750
751
752
753
754

	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);

755
756
			if (!swsusp_page_is_forbidden(page))
				swsusp_unset_page_free(page);
757
		}
Linus Torvalds's avatar
Linus Torvalds committed
758
759
760

	for (order = MAX_ORDER - 1; order >= 0; --order)
		list_for_each(curr, &zone->free_area[order].free_list) {
761
			unsigned long i;
Linus Torvalds's avatar
Linus Torvalds committed
762

763
764
			pfn = page_to_pfn(list_entry(curr, struct page, lru));
			for (i = 0; i < (1UL << order); i++)
765
				swsusp_set_page_free(pfn_to_page(pfn + i));
766
		}
Linus Torvalds's avatar
Linus Torvalds committed
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

	spin_unlock_irqrestore(&zone->lock, flags);
}

/*
 * Spill all of this CPU's per-cpu pages back into the buddy allocator.
 */
void drain_local_pages(void)
{
	unsigned long flags;

	local_irq_save(flags);	
	__drain_pages(smp_processor_id());
	local_irq_restore(flags);	
}
#endif /* CONFIG_PM */

/*
 * Free a 0-order page
 */
static void fastcall free_hot_cold_page(struct page *page, int cold)
{
	struct zone *zone = page_zone(page);
	struct per_cpu_pages *pcp;
	unsigned long flags;

	if (PageAnon(page))
		page->mapping = NULL;
795
	if (free_pages_check(page))
796
797
		return;

Nick Piggin's avatar
Nick Piggin committed
798
799
	if (!PageHighMem(page))
		debug_check_no_locks_freed(page_address(page), PAGE_SIZE);
Nick Piggin's avatar
Nick Piggin committed
800
	arch_free_page(page, 0);
801
802
	kernel_map_pages(page, 1, 0);

803
	pcp = &zone_pcp(zone, get_cpu())->pcp[cold];
Linus Torvalds's avatar
Linus Torvalds committed
804
	local_irq_save(flags);
805
	__count_vm_event(PGFREE);
Linus Torvalds's avatar
Linus Torvalds committed
806
807
	list_add(&page->lru, &pcp->list);
	pcp->count++;
Nick Piggin's avatar
Nick Piggin committed
808
809
810
811
	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
812
813
814
815
816
817
818
819
820
821
822
823
824
825
	local_irq_restore(flags);
	put_cpu();
}

void fastcall free_hot_page(struct page *page)
{
	free_hot_cold_page(page, 0);
}
	
void fastcall free_cold_page(struct page *page)
{
	free_hot_cold_page(page, 1);
}

826
827
828
829
830
831
832
833
834
835
836
837
/*
 * 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
838
839
	VM_BUG_ON(PageCompound(page));
	VM_BUG_ON(!page_count(page));
840
841
	for (i = 1; i < (1 << order); i++)
		set_page_refcounted(page + i);
842
843
}

Linus Torvalds's avatar
Linus Torvalds committed
844
845
846
847
848
/*
 * 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.
 */
Nick Piggin's avatar
Nick Piggin committed
849
850
static struct page *buffered_rmqueue(struct zonelist *zonelist,
			struct zone *zone, int order, gfp_t gfp_flags)
Linus Torvalds's avatar
Linus Torvalds committed
851
852
{
	unsigned long flags;
853
	struct page *page;
Linus Torvalds's avatar
Linus Torvalds committed
854
	int cold = !!(gfp_flags & __GFP_COLD);
Nick Piggin's avatar
Nick Piggin committed
855
	int cpu;
Linus Torvalds's avatar
Linus Torvalds committed
856

857
again:
Nick Piggin's avatar
Nick Piggin committed
858
	cpu  = get_cpu();
Nick Piggin's avatar
Nick Piggin committed
859
	if (likely(order == 0)) {
Linus Torvalds's avatar
Linus Torvalds committed
860
861
		struct per_cpu_pages *pcp;

Nick Piggin's avatar
Nick Piggin committed
862
		pcp = &zone_pcp(zone, cpu)->pcp[cold];
Linus Torvalds's avatar
Linus Torvalds committed
863
		local_irq_save(flags);
Nick Piggin's avatar
Nick Piggin committed
864
		if (!pcp->count) {
865
			pcp->count = rmqueue_bulk(zone, 0,
Linus Torvalds's avatar
Linus Torvalds committed
866
						pcp->batch, &pcp->list);
Nick Piggin's avatar
Nick Piggin committed
867
868
			if (unlikely(!pcp->count))
				goto failed;
Linus Torvalds's avatar
Linus Torvalds committed
869
		}
Nick Piggin's avatar
Nick Piggin committed
870
871
872
		page = list_entry(pcp->list.next, struct page, lru);
		list_del(&page->lru);
		pcp->count--;
Rohit Seth's avatar
Rohit Seth committed
873
	} else {
Linus Torvalds's avatar
Linus Torvalds committed
874
875
		spin_lock_irqsave(&zone->lock, flags);
		page = __rmqueue(zone, order);
Nick Piggin's avatar
Nick Piggin committed
876
877
878
		spin_unlock(&zone->lock);
		if (!page)
			goto failed;
Linus Torvalds's avatar
Linus Torvalds committed
879
880
	}

881
	__count_zone_vm_events(PGALLOC, zone, 1 << order);
882
	zone_statistics(zonelist, zone);
Nick Piggin's avatar
Nick Piggin committed
883
884
	local_irq_restore(flags);
	put_cpu();
Linus Torvalds's avatar
Linus Torvalds committed
885

Nick Piggin's avatar
Nick Piggin committed
886
	VM_BUG_ON(bad_range(zone, page));
Nick Piggin's avatar
Nick Piggin committed
887
	if (prep_new_page(page, order, gfp_flags))
Nick Piggin's avatar
Nick Piggin committed
888
		goto again;
Linus Torvalds's avatar
Linus Torvalds committed
889
	return page;
Nick Piggin's avatar
Nick Piggin committed
890
891
892
893
894

failed:
	local_irq_restore(flags);
	put_cpu();
	return NULL;
Linus Torvalds's avatar
Linus Torvalds committed
895
896
}

Rohit Seth's avatar
Rohit Seth committed
897
#define ALLOC_NO_WATERMARKS	0x01 /* don't check watermarks at all */
898
899
900
901
902
903
#define ALLOC_WMARK_MIN		0x02 /* use pages_min watermark */
#define ALLOC_WMARK_LOW		0x04 /* use pages_low watermark */
#define ALLOC_WMARK_HIGH	0x08 /* use pages_high watermark */
#define ALLOC_HARDER		0x10 /* try to alloc harder */
#define ALLOC_HIGH		0x20 /* __GFP_HIGH set */
#define ALLOC_CPUSET		0x40 /* check for correct cpuset */
Rohit Seth's avatar
Rohit Seth committed
904

905
906
907
908
909
910
911
#ifdef CONFIG_FAIL_PAGE_ALLOC

static struct fail_page_alloc_attr {
	struct fault_attr attr;

	u32 ignore_gfp_highmem;
	u32 ignore_gfp_wait;
912
	u32 min_order;
913
914
915
916
917

#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS

	struct dentry *ignore_gfp_highmem_file;
	struct dentry *ignore_gfp_wait_file;
918
	struct dentry *min_order_file;
919
920
921
922
923

#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */

} fail_page_alloc = {
	.attr = FAULT_ATTR_INITIALIZER,
924
925
	.ignore_gfp_wait = 1,
	.ignore_gfp_highmem = 1,
926
	.min_order = 1,
927
928
929
930
931
932
933
934
935
936
};

static int __init setup_fail_page_alloc(char *str)
{
	return setup_fault_attr(&fail_page_alloc.attr, str);
}
__setup("fail_page_alloc=", setup_fail_page_alloc);

static int should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
{
937
938
	if (order < fail_page_alloc.min_order)
		return 0;
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
	if (gfp_mask & __GFP_NOFAIL)
		return 0;
	if (fail_page_alloc.ignore_gfp_highmem && (gfp_mask & __GFP_HIGHMEM))
		return 0;
	if (fail_page_alloc.ignore_gfp_wait && (gfp_mask & __GFP_WAIT))
		return 0;

	return should_fail(&fail_page_alloc.attr, 1 << order);
}

#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS

static int __init fail_page_alloc_debugfs(void)
{
	mode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
	struct dentry *dir;
	int err;

	err = init_fault_attr_dentries(&fail_page_alloc.attr,
				       "fail_page_alloc");
	if (err)
		return err;
	dir = fail_page_alloc.attr.dentries.dir;

	fail_page_alloc.ignore_gfp_wait_file =
		debugfs_create_bool("ignore-gfp-wait", mode, dir,
				      &fail_page_alloc.ignore_gfp_wait);

	fail_page_alloc.ignore_gfp_highmem_file =
		debugfs_create_bool("ignore-gfp-highmem", mode, dir,
				      &fail_page_alloc.ignore_gfp_highmem);
970
971
972
	fail_page_alloc.min_order_file =
		debugfs_create_u32("min-order", mode, dir,
				   &fail_page_alloc.min_order);
973
974

	if (!fail_page_alloc.ignore_gfp_wait_file ||
975
976
            !fail_page_alloc.ignore_gfp_highmem_file ||
            !fail_page_alloc.min_order_file) {
977
978
979
		err = -ENOMEM;
		debugfs_remove(fail_page_alloc.ignore_gfp_wait_file);
		debugfs_remove(fail_page_alloc.ignore_gfp_highmem_file);
980
		debugfs_remove(fail_page_alloc.min_order_file);
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
		cleanup_fault_attr_dentries(&fail_page_alloc.attr);
	}

	return err;
}

late_initcall(fail_page_alloc_debugfs);

#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */

#else /* CONFIG_FAIL_PAGE_ALLOC */

static inline int should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
{
	return 0;
}

#endif /* CONFIG_FAIL_PAGE_ALLOC */

Linus Torvalds's avatar
Linus Torvalds committed
1000
1001
1002
1003
1004
/*
 * Return 1 if free pages are above 'mark'. This takes into account the order
 * of the allocation.
 */
int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
Rohit Seth's avatar
Rohit Seth committed
1005
		      int classzone_idx, int alloc_flags)
Linus Torvalds's avatar
Linus Torvalds committed
1006
1007
{
	/* free_pages my go negative - that's OK */
1008
1009
	long min = mark;
	long free_pages = zone_page_state(z, NR_FREE_PAGES) - (1 << order) + 1;
Linus Torvalds's avatar
Linus Torvalds committed
1010
1011
	int o;

Rohit Seth's avatar
Rohit Seth committed
1012
	if (alloc_flags & ALLOC_HIGH)
Linus Torvalds's avatar
Linus Torvalds committed
1013
		min -= min / 2;
Rohit Seth's avatar
Rohit Seth committed
1014
	if (alloc_flags & ALLOC_HARDER)
Linus Torvalds's avatar
Linus Torvalds committed
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
		min -= min / 4;

	if (free_pages <= min + z->lowmem_reserve[classzone_idx])
		return 0;
	for (o = 0; o < order; o++) {
		/* At the next order, this order's pages become unavailable */
		free_pages -= z->free_area[o].nr_free << o;

		/* Require fewer higher order pages to be free */
		min >>= 1;

		if (free_pages <= min)
			return 0;
	}
	return 1;
}

1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
#ifdef CONFIG_NUMA
/*
 * zlc_setup - Setup for "zonelist cache".  Uses cached zone data to
 * skip over zones that are not allowed by the cpuset, or that have
 * been recently (in last second) found to be nearly full.  See further
 * comments in mmzone.h.  Reduces cache footprint of zonelist scans
 * that have to skip over alot of full or unallowed zones.
 *
 * If the zonelist cache is present in the passed in zonelist, then
 * returns a pointer to the allowed node mask (either the current
 * tasks mems_allowed, or node_online_map.)
 *
 * If the zonelist cache is not available for this zonelist, does
 * nothing and returns NULL.
 *
 * If the fullzones BITMAP in the zonelist cache is stale (more than
 * a second since last zap'd) then we zap it out (clear its bits.)
 *
 * We hold off even calling zlc_setup, until after we've checked the
 * first zone in the zonelist, on the theory that most allocations will
 * be satisfied from that first zone, so best to examine that zone as
 * quickly as we can.
 */
static nodemask_t *zlc_setup(struct zonelist *zonelist, int alloc_flags)
{
	struct zonelist_cache *zlc;	/* cached zonelist speedup info */
	nodemask_t *allowednodes;	/* zonelist_cache approximation */

	zlc = zonelist->zlcache_ptr;
	if (!zlc)
		return NULL;

	if (jiffies - zlc->last_full_zap > 1 * HZ) {
		bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST);
		zlc->last_full_zap = jiffies;
	}

	allowednodes = !in_interrupt() && (alloc_flags & ALLOC_CPUSET) ?
					&cpuset_current_mems_allowed :
					&node_online_map;
	return allowednodes;
}

/*
 * Given 'z' scanning a zonelist, run a couple of quick checks to see
 * if it is worth looking at further for free memory:
 *  1) Check that the zone isn't thought to be full (doesn't have its
 *     bit set in the zonelist_cache fullzones BITMAP).
 *  2) Check that the zones node (obtained from the zonelist_cache
 *     z_to_n[] mapping) is allowed in the passed in allowednodes mask.
 * Return true (non-zero) if zone is worth looking at further, or
 * else return false (zero) if it is not.
 *
 * This check -ignores- the distinction between various watermarks,
 * such as GFP_HIGH, GFP_ATOMIC, PF_MEMALLOC, ...  If a zone is
 * found to be full for any variation of these watermarks, it will
 * be considered full for up to one second by all requests, unless
 * we are so low on memory on all allowed nodes that we are forced
 * into the second scan of the zonelist.
 *
 * In the second scan we ignore this zonelist cache and exactly
 * apply the watermarks to all zones, even it is slower to do so.
 * We are low on memory in the second scan, and should leave no stone
 * unturned looking for a free page.
 */
static int zlc_zone_worth_trying(struct zonelist *zonelist, struct zone **z,
						nodemask_t *allowednodes)
{
	struct zonelist_cache *zlc;	/* cached zonelist speedup info */
	int i;				/* index of *z in zonelist zones */
	int n;				/* node that zone *z is on */

	zlc = zonelist->zlcache_ptr;
	if (!zlc)
		return 1;

	i = z - zonelist->zones;
	n = zlc->z_to_n[i];

	/* This zone is worth trying if it is allowed but not full */
	return node_isset(n, *allowednodes) && !test_bit(i, zlc->fullzones);
}

/*
 * Given 'z' scanning a zonelist, set the corresponding bit in
 * zlc->fullzones, so that subsequent attempts to allocate a page
 * from that zone don't waste time re-examining it.
 */
static void zlc_mark_zone_full(struct zonelist *zonelist, struct zone **z)
{
	struct zonelist_cache *zlc;	/* cached zonelist speedup info */
	int i;				/* index of *z in zonelist zones */

	zlc = zonelist->zlcache_ptr;
	if (!zlc)
		return;

	i = z - zonelist->zones;

	set_bit(i, zlc->fullzones);
}

#else	/* CONFIG_NUMA */

static nodemask_t *zlc_setup(struct zonelist *zonelist, int alloc_flags)
{
	return NULL;
}

static int zlc_zone_worth_trying(struct zonelist *zonelist, struct zone **z,
				nodemask_t *allowednodes)
{
	return 1;
}

static void zlc_mark_zone_full(struct zonelist *zonelist, struct zone **z)
{
}
#endif	/* CONFIG_NUMA */

Rohit Seth's avatar
Rohit Seth committed
1152
/*
1153
 * get_page_from_freelist goes through the zonelist trying to allocate
Rohit Seth's avatar
Rohit Seth committed
1154
1155
1156
1157
1158
 * a page.
 */
static struct page *
get_page_from_freelist(gfp_t gfp_mask, unsigned int order,
		struct zonelist *zonelist, int alloc_flags)
Martin Hicks's avatar
Martin Hicks committed
1159
{
1160
	struct zone **z;
Rohit Seth's avatar
Rohit Seth committed
1161
	struct page *page = NULL;
1162
	int classzone_idx = zone_idx(zonelist->zones[0]);
1163
	struct zone *zone;
1164
1165
1166
	nodemask_t *allowednodes = NULL;/* zonelist_cache approximation */
	int zlc_active = 0;		/* set if using zonelist_cache */
	int did_zlc_setup = 0;		/* just call zlc_setup() one time */
Rohit Seth's avatar
Rohit Seth committed
1167

1168
zonelist_scan:
Rohit Seth's avatar
Rohit Seth committed
1169
	/*
1170
	 * Scan zonelist, looking for a zone with enough free.
Rohit Seth's avatar
Rohit Seth committed
1171
1172
	 * See also cpuset_zone_allowed() comment in kernel/cpuset.c.
	 */
1173
1174
	z = zonelist->zones;

Rohit Seth's avatar
Rohit Seth committed
1175
	do {
1176
1177
1178
		if (NUMA_BUILD && zlc_active &&
			!zlc_zone_worth_trying(zonelist, z, allowednodes))
				continue;
1179
		zone = *z;
1180
		if (unlikely(NUMA_BUILD && (gfp_mask & __GFP_THISNODE) &&
1181
			zone->zone_pgdat != zonelist->zones[0]->zone_pgdat))
1182
				break;
Rohit Seth's avatar
Rohit Seth committed
1183
		if ((alloc_flags & ALLOC_CPUSET) &&
1184
			!cpuset_zone_allowed_softwall(zone, gfp_mask))
1185
				goto try_next_zone;
Rohit Seth's avatar
Rohit Seth committed
1186
1187

		if (!(alloc_flags & ALLOC_NO_WATERMARKS)) {
1188
1189
			unsigned long mark;
			if (alloc_flags & ALLOC_WMARK_MIN)
1190
				mark = zone->pages_min;
1191
			else if (alloc_flags & ALLOC_WMARK_LOW)
1192
				mark = zone->pages_low