page_alloc.c 146 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>
26
#include <linux/kmemcheck.h>
Linus Torvalds's avatar
Linus Torvalds committed
27 28 29 30 31
#include <linux/module.h>
#include <linux/suspend.h>
#include <linux/pagevec.h>
#include <linux/blkdev.h>
#include <linux/slab.h>
32
#include <linux/oom.h>
Linus Torvalds's avatar
Linus Torvalds committed
33 34 35 36 37
#include <linux/notifier.h>
#include <linux/topology.h>
#include <linux/sysctl.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
38
#include <linux/memory_hotplug.h>
Linus Torvalds's avatar
Linus Torvalds committed
39 40
#include <linux/nodemask.h>
#include <linux/vmalloc.h>
41
#include <linux/mempolicy.h>
42
#include <linux/stop_machine.h>
43 44
#include <linux/sort.h>
#include <linux/pfn.h>
45
#include <linux/backing-dev.h>
46
#include <linux/fault-inject.h>
47
#include <linux/page-isolation.h>
48
#include <linux/page_cgroup.h>
49
#include <linux/debugobjects.h>
50
#include <linux/kmemleak.h>
51
#include <linux/memory.h>
52
#include <trace/events/kmem.h>
53
#include <linux/ftrace_event.h>
Linus Torvalds's avatar
Linus Torvalds committed
54 55

#include <asm/tlbflush.h>
56
#include <asm/div64.h>
Linus Torvalds's avatar
Linus Torvalds committed
57 58 59
#include "internal.h"

/*
60
 * Array of node states.
Linus Torvalds's avatar
Linus Torvalds committed
61
 */
62 63 64 65 66 67 68 69 70 71 72 73 74
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);

75
unsigned long totalram_pages __read_mostly;
76
unsigned long totalreserve_pages __read_mostly;
77
int percpu_pagelist_fraction;
78
gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
Linus Torvalds's avatar
Linus Torvalds committed
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
#ifdef CONFIG_PM_SLEEP
/*
 * The following functions are used by the suspend/hibernate code to temporarily
 * change gfp_allowed_mask in order to avoid using I/O during memory allocations
 * while devices are suspended.  To avoid races with the suspend/hibernate code,
 * they should always be called with pm_mutex held (gfp_allowed_mask also should
 * only be modified with pm_mutex held, unless the suspend/hibernate code is
 * guaranteed not to run in parallel with that modification).
 */
void set_gfp_allowed_mask(gfp_t mask)
{
	WARN_ON(!mutex_is_locked(&pm_mutex));
	gfp_allowed_mask = mask;
}

gfp_t clear_gfp_allowed_mask(gfp_t mask)
{
	gfp_t ret = gfp_allowed_mask;

	WARN_ON(!mutex_is_locked(&pm_mutex));
	gfp_allowed_mask &= ~mask;
	return ret;
}
#endif /* CONFIG_PM_SLEEP */

105 106 107 108
#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
int pageblock_order __read_mostly;
#endif

109
static void __free_pages_ok(struct page *page, unsigned int order);
110

Linus Torvalds's avatar
Linus Torvalds committed
111 112 113 114 115 116 117
/*
 * 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
118 119 120
 *
 * 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
121
 */
122
int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
123
#ifdef CONFIG_ZONE_DMA
124
	 256,
125
#endif
126
#ifdef CONFIG_ZONE_DMA32
127
	 256,
128
#endif
129
#ifdef CONFIG_HIGHMEM
Mel Gorman's avatar
Mel Gorman committed
130
	 32,
131
#endif
Mel Gorman's avatar
Mel Gorman committed
132
	 32,
133
};
Linus Torvalds's avatar
Linus Torvalds committed
134 135 136

EXPORT_SYMBOL(totalram_pages);

137
static char * const zone_names[MAX_NR_ZONES] = {
138
#ifdef CONFIG_ZONE_DMA
139
	 "DMA",
140
#endif
141
#ifdef CONFIG_ZONE_DMA32
142
	 "DMA32",
143
#endif
144
	 "Normal",
145
#ifdef CONFIG_HIGHMEM
Mel Gorman's avatar
Mel Gorman committed
146
	 "HighMem",
147
#endif
Mel Gorman's avatar
Mel Gorman committed
148
	 "Movable",
149 150
};

Linus Torvalds's avatar
Linus Torvalds committed
151 152
int min_free_kbytes = 1024;

153 154
static unsigned long __meminitdata nr_kernel_pages;
static unsigned long __meminitdata nr_all_pages;
155
static unsigned long __meminitdata dma_reserve;
Linus Torvalds's avatar
Linus Torvalds committed
156

157 158
#ifdef CONFIG_ARCH_POPULATES_NODE_MAP
  /*
Simon Arlott's avatar
Simon Arlott committed
159
   * MAX_ACTIVE_REGIONS determines the maximum number of distinct
160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177
   * 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

178 179 180 181
  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];
Adrian Bunk's avatar
Adrian Bunk committed
182
  static unsigned long __initdata required_kernelcore;
183
  static unsigned long __initdata required_movablecore;
Adrian Bunk's avatar
Adrian Bunk committed
184
  static unsigned long __meminitdata zone_movable_pfn[MAX_NUMNODES];
Mel Gorman's avatar
Mel Gorman committed
185 186 187 188

  /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
  int movable_zone;
  EXPORT_SYMBOL(movable_zone);
189 190
#endif /* CONFIG_ARCH_POPULATES_NODE_MAP */

Miklos Szeredi's avatar
Miklos Szeredi committed
191 192
#if MAX_NUMNODES > 1
int nr_node_ids __read_mostly = MAX_NUMNODES;
193
int nr_online_nodes __read_mostly = 1;
Miklos Szeredi's avatar
Miklos Szeredi committed
194
EXPORT_SYMBOL(nr_node_ids);
195
EXPORT_SYMBOL(nr_online_nodes);
Miklos Szeredi's avatar
Miklos Szeredi committed
196 197
#endif

198 199
int page_group_by_mobility_disabled __read_mostly;

200 201
static void set_pageblock_migratetype(struct page *page, int migratetype)
{
202 203 204 205

	if (unlikely(page_group_by_mobility_disabled))
		migratetype = MIGRATE_UNMOVABLE;

206 207 208 209
	set_pageblock_flags_group(page, (unsigned long)migratetype,
					PB_migrate, PB_migrate_end);
}

210 211
bool oom_killer_disabled __read_mostly;

Nick Piggin's avatar
Nick Piggin committed
212
#ifdef CONFIG_DEBUG_VM
213
static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
214
{
215 216 217
	int ret = 0;
	unsigned seq;
	unsigned long pfn = page_to_pfn(page);
218

219 220 221 222 223 224 225 226 227
	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;
228 229 230 231
}

static int page_is_consistent(struct zone *zone, struct page *page)
{
232
	if (!pfn_valid_within(page_to_pfn(page)))
233
		return 0;
Linus Torvalds's avatar
Linus Torvalds committed
234
	if (zone != page_zone(page))
235 236 237 238 239 240 241 242 243 244
		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
245
		return 1;
246 247 248
	if (!page_is_consistent(zone, page))
		return 1;

Linus Torvalds's avatar
Linus Torvalds committed
249 250
	return 0;
}
Nick Piggin's avatar
Nick Piggin committed
251 252 253 254 255 256 257
#else
static inline int bad_range(struct zone *zone, struct page *page)
{
	return 0;
}
#endif

258
static void bad_page(struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
259
{
260 261 262 263
	static unsigned long resume;
	static unsigned long nr_shown;
	static unsigned long nr_unshown;

264 265 266 267 268 269
	/* Don't complain about poisoned pages */
	if (PageHWPoison(page)) {
		__ClearPageBuddy(page);
		return;
	}

270 271 272 273 274 275 276 277 278 279
	/*
	 * Allow a burst of 60 reports, then keep quiet for that minute;
	 * or allow a steady drip of one report per second.
	 */
	if (nr_shown == 60) {
		if (time_before(jiffies, resume)) {
			nr_unshown++;
			goto out;
		}
		if (nr_unshown) {
280 281
			printk(KERN_ALERT
			      "BUG: Bad page state: %lu messages suppressed\n",
282 283 284 285 286 287 288 289
				nr_unshown);
			nr_unshown = 0;
		}
		nr_shown = 0;
	}
	if (nr_shown++ == 0)
		resume = jiffies + 60 * HZ;

290
	printk(KERN_ALERT "BUG: Bad page state in process %s  pfn:%05lx\n",
291
		current->comm, page_to_pfn(page));
292
	dump_page(page);
293

Linus Torvalds's avatar
Linus Torvalds committed
294
	dump_stack();
295
out:
296 297
	/* Leave bad fields for debug, except PageBuddy could make trouble */
	__ClearPageBuddy(page);
298
	add_taint(TAINT_BAD_PAGE);
Linus Torvalds's avatar
Linus Torvalds committed
299 300 301 302 303 304 305 306 307 308 309 310
}

/*
 * 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).
 *
311 312 313
 * 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
314
 */
315 316 317

static void free_compound_page(struct page *page)
{
318
	__free_pages_ok(page, compound_order(page));
319 320
}

321
void prep_compound_page(struct page *page, unsigned long order)
322 323 324 325 326 327 328 329 330 331 332 333 334 335 336
{
	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;
	}
}

337
static int destroy_compound_page(struct page *page, unsigned long order)
Linus Torvalds's avatar
Linus Torvalds committed
338 339 340
{
	int i;
	int nr_pages = 1 << order;
341
	int bad = 0;
Linus Torvalds's avatar
Linus Torvalds committed
342

343 344
	if (unlikely(compound_order(page) != order) ||
	    unlikely(!PageHead(page))) {
345
		bad_page(page);
346 347
		bad++;
	}
Linus Torvalds's avatar
Linus Torvalds committed
348

349
	__ClearPageHead(page);
350

351 352
	for (i = 1; i < nr_pages; i++) {
		struct page *p = page + i;
Linus Torvalds's avatar
Linus Torvalds committed
353

354
		if (unlikely(!PageTail(p) || (p->first_page != page))) {
355
			bad_page(page);
356 357
			bad++;
		}
358
		__ClearPageTail(p);
Linus Torvalds's avatar
Linus Torvalds committed
359
	}
360 361

	return bad;
Linus Torvalds's avatar
Linus Torvalds committed
362 363
}

Nick Piggin's avatar
Nick Piggin committed
364 365 366 367
static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags)
{
	int i;

368 369 370 371
	/*
	 * 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
372
	VM_BUG_ON((gfp_flags & __GFP_HIGHMEM) && in_interrupt());
Nick Piggin's avatar
Nick Piggin committed
373 374 375 376
	for (i = 0; i < (1 << order); i++)
		clear_highpage(page + i);
}

377 378
static inline void set_page_order(struct page *page, int order)
{
379
	set_page_private(page, order);
380
	__SetPageBuddy(page);
Linus Torvalds's avatar
Linus Torvalds committed
381 382 383 384
}

static inline void rmv_page_order(struct page *page)
{
385
	__ClearPageBuddy(page);
386
	set_page_private(page, 0);
Linus Torvalds's avatar
Linus Torvalds committed
387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403
}

/*
 * 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
404
 * Assumption: *_mem_map is contiguous at least up to MAX_ORDER
Linus Torvalds's avatar
Linus Torvalds committed
405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422
 */
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
423
 * (a) the buddy is not in a hole &&
424
 * (b) the buddy is in the buddy system &&
425 426
 * (c) a page and its buddy have the same order &&
 * (d) a page and its buddy are in the same zone.
427 428 429
 *
 * 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
430
 *
431
 * For recording page's order, we use page_private(page).
Linus Torvalds's avatar
Linus Torvalds committed
432
 */
433 434
static inline int page_is_buddy(struct page *page, struct page *buddy,
								int order)
Linus Torvalds's avatar
Linus Torvalds committed
435
{
436
	if (!pfn_valid_within(page_to_pfn(buddy)))
Nick Piggin's avatar
Nick Piggin committed
437 438
		return 0;

439 440 441 442
	if (page_zone_id(page) != page_zone_id(buddy))
		return 0;

	if (PageBuddy(buddy) && page_order(buddy) == order) {
443
		VM_BUG_ON(page_count(buddy) != 0);
444
		return 1;
445
	}
446
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
447 448 449 450 451 452 453 454 455 456 457 458 459 460 461
}

/*
 * 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
462
 * free pages of length of (1 << order) and marked with PG_buddy. Page's
463
 * order is recorded in page_private(page) field.
Linus Torvalds's avatar
Linus Torvalds committed
464 465 466 467 468 469 470 471 472
 * 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
473
static inline void __free_one_page(struct page *page,
474 475
		struct zone *zone, unsigned int order,
		int migratetype)
Linus Torvalds's avatar
Linus Torvalds committed
476 477
{
	unsigned long page_idx;
478 479
	unsigned long combined_idx;
	struct page *buddy;
Linus Torvalds's avatar
Linus Torvalds committed
480

481
	if (unlikely(PageCompound(page)))
482 483
		if (unlikely(destroy_compound_page(page, order)))
			return;
Linus Torvalds's avatar
Linus Torvalds committed
484

485 486
	VM_BUG_ON(migratetype == -1);

Linus Torvalds's avatar
Linus Torvalds committed
487 488
	page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);

489
	VM_BUG_ON(page_idx & ((1 << order) - 1));
Nick Piggin's avatar
Nick Piggin committed
490
	VM_BUG_ON(bad_range(zone, page));
Linus Torvalds's avatar
Linus Torvalds committed
491 492 493

	while (order < MAX_ORDER-1) {
		buddy = __page_find_buddy(page, page_idx, order);
494
		if (!page_is_buddy(page, buddy, order))
495
			break;
Nick Piggin's avatar
Nick Piggin committed
496

497
		/* Our buddy is free, merge with it and move up one order. */
Linus Torvalds's avatar
Linus Torvalds committed
498
		list_del(&buddy->lru);
499
		zone->free_area[order].nr_free--;
Linus Torvalds's avatar
Linus Torvalds committed
500
		rmv_page_order(buddy);
Nick Piggin's avatar
Nick Piggin committed
501
		combined_idx = __find_combined_index(page_idx, order);
Linus Torvalds's avatar
Linus Torvalds committed
502 503 504 505 506
		page = page + (combined_idx - page_idx);
		page_idx = combined_idx;
		order++;
	}
	set_page_order(page, order);
507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529

	/*
	 * If this is not the largest possible page, check if the buddy
	 * of the next-highest order is free. If it is, it's possible
	 * that pages are being freed that will coalesce soon. In case,
	 * that is happening, add the free page to the tail of the list
	 * so it's less likely to be used soon and more likely to be merged
	 * as a higher order page
	 */
	if ((order < MAX_ORDER-1) && pfn_valid_within(page_to_pfn(buddy))) {
		struct page *higher_page, *higher_buddy;
		combined_idx = __find_combined_index(page_idx, order);
		higher_page = page + combined_idx - page_idx;
		higher_buddy = __page_find_buddy(higher_page, combined_idx, order + 1);
		if (page_is_buddy(higher_page, higher_buddy, order + 1)) {
			list_add_tail(&page->lru,
				&zone->free_area[order].free_list[migratetype]);
			goto out;
		}
	}

	list_add(&page->lru, &zone->free_area[order].free_list[migratetype]);
out:
Linus Torvalds's avatar
Linus Torvalds committed
530 531 532
	zone->free_area[order].nr_free++;
}

533 534 535 536 537 538 539 540 541 542 543
/*
 * free_page_mlock() -- clean up attempts to free and mlocked() page.
 * Page should not be on lru, so no need to fix that up.
 * free_pages_check() will verify...
 */
static inline void free_page_mlock(struct page *page)
{
	__dec_zone_page_state(page, NR_MLOCK);
	__count_vm_event(UNEVICTABLE_MLOCKFREED);
}

544
static inline int free_pages_check(struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
545
{
Nick Piggin's avatar
Nick Piggin committed
546 547
	if (unlikely(page_mapcount(page) |
		(page->mapping != NULL)  |
548
		(atomic_read(&page->_count) != 0) |
549
		(page->flags & PAGE_FLAGS_CHECK_AT_FREE))) {
550
		bad_page(page);
551
		return 1;
552
	}
553 554 555
	if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
		page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
556 557 558
}

/*
559
 * Frees a number of pages from the PCP lists
Linus Torvalds's avatar
Linus Torvalds committed
560
 * Assumes all pages on list are in same zone, and of same order.
561
 * count is the number of pages to free.
Linus Torvalds's avatar
Linus Torvalds committed
562 563 564 565 566 567 568
 *
 * 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.
 */
569 570
static void free_pcppages_bulk(struct zone *zone, int count,
					struct per_cpu_pages *pcp)
Linus Torvalds's avatar
Linus Torvalds committed
571
{
572
	int migratetype = 0;
573
	int batch_free = 0;
574

Nick Piggin's avatar
Nick Piggin committed
575
	spin_lock(&zone->lock);
576
	zone->all_unreclaimable = 0;
Linus Torvalds's avatar
Linus Torvalds committed
577
	zone->pages_scanned = 0;
578

579
	__mod_zone_page_state(zone, NR_FREE_PAGES, count);
580
	while (count) {
Nick Piggin's avatar
Nick Piggin committed
581
		struct page *page;
582 583 584
		struct list_head *list;

		/*
585 586 587 588 589
		 * Remove pages from lists in a round-robin fashion. A
		 * batch_free count is maintained that is incremented when an
		 * empty list is encountered.  This is so more pages are freed
		 * off fuller lists instead of spinning excessively around empty
		 * lists
590 591
		 */
		do {
592
			batch_free++;
593 594 595 596
			if (++migratetype == MIGRATE_PCPTYPES)
				migratetype = 0;
			list = &pcp->lists[migratetype];
		} while (list_empty(list));
Nick Piggin's avatar
Nick Piggin committed
597

598 599 600 601
		do {
			page = list_entry(list->prev, struct page, lru);
			/* must delete as __free_one_page list manipulates */
			list_del(&page->lru);
602 603 604
			/* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */
			__free_one_page(page, zone, 0, page_private(page));
			trace_mm_page_pcpu_drain(page, 0, page_private(page));
605
		} while (--count && --batch_free && !list_empty(list));
Linus Torvalds's avatar
Linus Torvalds committed
606
	}
Nick Piggin's avatar
Nick Piggin committed
607
	spin_unlock(&zone->lock);
Linus Torvalds's avatar
Linus Torvalds committed
608 609
}

610 611
static void free_one_page(struct zone *zone, struct page *page, int order,
				int migratetype)
Linus Torvalds's avatar
Linus Torvalds committed
612
{
613
	spin_lock(&zone->lock);
614
	zone->all_unreclaimable = 0;
615
	zone->pages_scanned = 0;
616 617

	__mod_zone_page_state(zone, NR_FREE_PAGES, 1 << order);
618
	__free_one_page(page, zone, order, migratetype);
619
	spin_unlock(&zone->lock);
Nick Piggin's avatar
Nick Piggin committed
620 621 622 623 624
}

static void __free_pages_ok(struct page *page, unsigned int order)
{
	unsigned long flags;
Linus Torvalds's avatar
Linus Torvalds committed
625
	int i;
626
	int bad = 0;
627
	int wasMlocked = __TestClearPageMlocked(page);
Linus Torvalds's avatar
Linus Torvalds committed
628

629
	trace_mm_page_free_direct(page, order);
630 631
	kmemcheck_free_shadow(page, order);

Linus Torvalds's avatar
Linus Torvalds committed
632
	for (i = 0 ; i < (1 << order) ; ++i)
633 634
		bad += free_pages_check(page + i);
	if (bad)
635 636
		return;

637
	if (!PageHighMem(page)) {
Nick Piggin's avatar
Nick Piggin committed
638
		debug_check_no_locks_freed(page_address(page),PAGE_SIZE<<order);
639 640 641
		debug_check_no_obj_freed(page_address(page),
					   PAGE_SIZE << order);
	}
Nick Piggin's avatar
Nick Piggin committed
642
	arch_free_page(page, order);
Nick Piggin's avatar
Nick Piggin committed
643
	kernel_map_pages(page, 1 << order, 0);
Nick Piggin's avatar
Nick Piggin committed
644

Nick Piggin's avatar
Nick Piggin committed
645
	local_irq_save(flags);
646
	if (unlikely(wasMlocked))
647
		free_page_mlock(page);
648
	__count_vm_events(PGFREE, 1 << order);
649 650
	free_one_page(page_zone(page), page, order,
					get_pageblock_migratetype(page));
Nick Piggin's avatar
Nick Piggin committed
651
	local_irq_restore(flags);
Linus Torvalds's avatar
Linus Torvalds committed
652 653
}

654 655 656
/*
 * permit the bootmem allocator to evade page validation on high-order frees
 */
657
void __meminit __free_pages_bootmem(struct page *page, unsigned int order)
658 659 660 661
{
	if (order == 0) {
		__ClearPageReserved(page);
		set_page_count(page, 0);
662
		set_page_refcounted(page);
Nick Piggin's avatar
Nick Piggin committed
663
		__free_page(page);
664 665 666
	} else {
		int loop;

Nick Piggin's avatar
Nick Piggin committed
667
		prefetchw(page);
668 669 670
		for (loop = 0; loop < BITS_PER_LONG; loop++) {
			struct page *p = &page[loop];

Nick Piggin's avatar
Nick Piggin committed
671 672
			if (loop + 1 < BITS_PER_LONG)
				prefetchw(p + 1);
673 674 675 676
			__ClearPageReserved(p);
			set_page_count(p, 0);
		}

677
		set_page_refcounted(page);
Nick Piggin's avatar
Nick Piggin committed
678
		__free_pages(page, order);
679 680 681
	}
}

Linus Torvalds's avatar
Linus Torvalds committed
682 683 684 685 686 687 688 689 690 691 692 693 694 695 696

/*
 * 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
697
static inline void expand(struct zone *zone, struct page *page,
698 699
	int low, int high, struct free_area *area,
	int migratetype)
Linus Torvalds's avatar
Linus Torvalds committed
700 701 702 703 704 705 706
{
	unsigned long size = 1 << high;

	while (high > low) {
		area--;
		high--;
		size >>= 1;
Nick Piggin's avatar
Nick Piggin committed
707
		VM_BUG_ON(bad_range(zone, &page[size]));
708
		list_add(&page[size].lru, &area->free_list[migratetype]);
Linus Torvalds's avatar
Linus Torvalds committed
709 710 711 712 713 714 715 716
		area->nr_free++;
		set_page_order(&page[size], high);
	}
}

/*
 * This page is about to be returned from the page allocator
 */
717
static inline int check_new_page(struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
718
{
Nick Piggin's avatar
Nick Piggin committed
719 720
	if (unlikely(page_mapcount(page) |
		(page->mapping != NULL)  |
721
		(atomic_read(&page->_count) != 0)  |
722
		(page->flags & PAGE_FLAGS_CHECK_AT_PREP))) {
723
		bad_page(page);
724
		return 1;
725
	}
726 727 728 729 730 731 732 733 734 735 736 737
	return 0;
}

static int prep_new_page(struct page *page, int order, gfp_t gfp_flags)
{
	int i;

	for (i = 0; i < (1 << order); i++) {
		struct page *p = page + i;
		if (unlikely(check_new_page(p)))
			return 1;
	}
738

739
	set_page_private(page, 0);
740
	set_page_refcounted(page);
Nick Piggin's avatar
Nick Piggin committed
741 742

	arch_alloc_page(page, order);
Linus Torvalds's avatar
Linus Torvalds committed
743
	kernel_map_pages(page, 1 << order, 1);
Nick Piggin's avatar
Nick Piggin committed
744 745 746 747 748 749 750

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

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

751
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
752 753
}

754 755 756 757
/*
 * Go through the free lists for the given migratetype and remove
 * the smallest available page from the freelists
 */
758 759
static inline
struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
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
						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--;
		expand(zone, page, order, current_order, area, migratetype);
		return page;
	}

	return NULL;
}


785 786 787 788 789
/*
 * 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] = {
790 791 792 793
	[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 */
794 795
};

796 797
/*
 * Move the free pages in a range to the free lists of the requested type.
798
 * Note that start_page and end_pages are not aligned on a pageblock
799 800
 * boundary. If alignment is required, use move_freepages_block()
 */
Adrian Bunk's avatar
Adrian Bunk committed
801 802 803
static int move_freepages(struct zone *zone,
			  struct page *start_page, struct page *end_page,
			  int migratetype)
804 805 806
{
	struct page *page;
	unsigned long order;
807
	int pages_moved = 0;
808 809 810 811 812 813 814

#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
815
	 * grouping pages by mobility
816 817 818 819 820
	 */
	BUG_ON(page_zone(start_page) != page_zone(end_page));
#endif

	for (page = start_page; page <= end_page;) {
821 822 823
		/* Make sure we are not inadvertently changing nodes */
		VM_BUG_ON(page_to_nid(page) != zone_to_nid(zone));

824 825 826 827 828 829 830 831 832 833 834 835 836 837 838
		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;
839
		pages_moved += 1 << order;
840 841
	}

842
	return pages_moved;
843 844
}

Adrian Bunk's avatar
Adrian Bunk committed
845 846
static int move_freepages_block(struct zone *zone, struct page *page,
				int migratetype)
847 848 849 850 851
{
	unsigned long start_pfn, end_pfn;
	struct page *start_page, *end_page;

	start_pfn = page_to_pfn(page);
852
	start_pfn = start_pfn & ~(pageblock_nr_pages-1);
853
	start_page = pfn_to_page(start_pfn);
854 855
	end_page = start_page + pageblock_nr_pages - 1;
	end_pfn = start_pfn + pageblock_nr_pages - 1;
856 857 858 859 860 861 862 863 864 865

	/* 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);
}

866 867 868 869 870 871 872 873 874 875 876
static void change_pageblock_range(struct page *pageblock_page,
					int start_order, int migratetype)
{
	int nr_pageblocks = 1 << (start_order - pageblock_order);

	while (nr_pageblocks--) {
		set_pageblock_migratetype(pageblock_page, migratetype);
		pageblock_page += pageblock_nr_pages;
	}
}

877
/* Remove an element from the buddy allocator from the fallback list */
878 879
static inline struct page *
__rmqueue_fallback(struct zone *zone, int order, int start_migratetype)
880 881 882 883 884 885 886 887 888 889 890 891
{
	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];

892 893 894
			/* MIGRATE_RESERVE handled later if necessary */
			if (migratetype == MIGRATE_RESERVE)
				continue;
895

896 897 898 899 900 901 902 903 904
			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--;

			/*
905
			 * If breaking a large block of pages, move all free
906 907 908
			 * pages to the preferred allocation list. If falling
			 * back for a reclaimable kernel allocation, be more
			 * agressive about taking ownership of free pages
909
			 */
910
			if (unlikely(current_order >= (pageblock_order >> 1)) ||
911 912
					start_migratetype == MIGRATE_RECLAIMABLE ||
					page_group_by_mobility_disabled) {
913 914 915 916 917
				unsigned long pages;
				pages = move_freepages_block(zone, page,
								start_migratetype);

				/* Claim the whole block if over half of it is free */
918 919
				if (pages >= (1 << (pageblock_order-1)) ||
						page_group_by_mobility_disabled)
920 921 922
					set_pageblock_migratetype(page,
								start_migratetype);

923
				migratetype = start_migratetype;
924
			}
925 926 927 928 929

			/* Remove the page from the freelists */
			list_del(&page->lru);
			rmv_page_order(page);

930 931 932
			/* Take ownership for orders >= pageblock_order */
			if (current_order >= pageblock_order)
				change_pageblock_range(page, current_order,
933 934 935
							start_migratetype);

			expand(zone, page, order, current_order, area, migratetype);
936 937 938 939

			trace_mm_page_alloc_extfrag(page, order, current_order,
				start_migratetype, migratetype);

940 941 942 943
			return page;
		}
	}

944
	return NULL;
945 946
}

947
/*
Linus Torvalds's avatar
Linus Torvalds committed
948 949 950
 * Do the hard work of removing an element from the buddy allocator.
 * Call me with the zone->lock already held.
 */
951 952
static struct page *__rmqueue(struct zone *zone, unsigned int order,
						int migratetype)
Linus Torvalds's avatar
Linus Torvalds committed
953 954 955
{
	struct page *page;

956
retry_reserve:
957
	page = __rmqueue_smallest(zone, order, migratetype);
958

959
	if (unlikely(!page) && migratetype != MIGRATE_RESERVE) {
960
		page = __rmqueue_fallback(zone, order, migratetype);
961

962 963 964 965 966 967 968 969 970 971 972
		/*
		 * Use MIGRATE_RESERVE rather than fail an allocation. goto
		 * is used because __rmqueue_smallest is an inline function
		 * and we want just one call site
		 */
		if (!page) {
			migratetype = MIGRATE_RESERVE;
			goto retry_reserve;
		}
	}

973
	trace_mm_page_alloc_zone_locked(page, order, migratetype);
974
	return page;
Linus Torvalds's avatar
Linus Torvalds committed
975 976 977 978 979 980 981 982
}

/* 
 * 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, 
983
			unsigned long count, struct list_head *list,
984
			int migratetype, int cold)
Linus Torvalds's avatar
Linus Torvalds committed
985 986 987
{
	int i;
	
Nick Piggin's avatar
Nick Piggin committed
988
	spin_lock(&zone->lock);
Linus Torvalds's avatar
Linus Torvalds committed
989
	for (i = 0; i < count; ++i) {
990
		struct page *page = __rmqueue(zone, order, migratetype);