page_alloc.c 150 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 <linux/compaction.h>
53
#include <trace/events/kmem.h>
54
#include <linux/ftrace_event.h>
Linus Torvalds's avatar
Linus Torvalds committed
55 56

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

60 61 62 63 64
#ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
DEFINE_PER_CPU(int, numa_node);
EXPORT_PER_CPU_SYMBOL(numa_node);
#endif

65 66 67 68 69 70 71 72 73 74 75
#ifdef CONFIG_HAVE_MEMORYLESS_NODES
/*
 * N.B., Do NOT reference the '_numa_mem_' per cpu variable directly.
 * It will not be defined when CONFIG_HAVE_MEMORYLESS_NODES is not defined.
 * Use the accessor functions set_numa_mem(), numa_mem_id() and cpu_to_mem()
 * defined in <linux/topology.h>.
 */
DEFINE_PER_CPU(int, _numa_mem_);		/* Kernel "local memory" node */
EXPORT_PER_CPU_SYMBOL(_numa_mem_);
#endif

Linus Torvalds's avatar
Linus Torvalds committed
76
/*
77
 * Array of node states.
Linus Torvalds's avatar
Linus Torvalds committed
78
 */
79 80 81 82 83 84 85 86 87 88 89 90 91
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);

92
unsigned long totalram_pages __read_mostly;
93
unsigned long totalreserve_pages __read_mostly;
94
int percpu_pagelist_fraction;
95
gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
Linus Torvalds's avatar
Linus Torvalds committed
96

97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121
#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 */

122 123 124 125
#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
int pageblock_order __read_mostly;
#endif

126
static void __free_pages_ok(struct page *page, unsigned int order);
127

Linus Torvalds's avatar
Linus Torvalds committed
128 129 130 131 132 133 134
/*
 * 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
135 136 137
 *
 * 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
138
 */
139
int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
140
#ifdef CONFIG_ZONE_DMA
141
	 256,
142
#endif
143
#ifdef CONFIG_ZONE_DMA32
144
	 256,
145
#endif
146
#ifdef CONFIG_HIGHMEM
Mel Gorman's avatar
Mel Gorman committed
147
	 32,
148
#endif
Mel Gorman's avatar
Mel Gorman committed
149
	 32,
150
};
Linus Torvalds's avatar
Linus Torvalds committed
151 152 153

EXPORT_SYMBOL(totalram_pages);

154
static char * const zone_names[MAX_NR_ZONES] = {
155
#ifdef CONFIG_ZONE_DMA
156
	 "DMA",
157
#endif
158
#ifdef CONFIG_ZONE_DMA32
159
	 "DMA32",
160
#endif
161
	 "Normal",
162
#ifdef CONFIG_HIGHMEM
Mel Gorman's avatar
Mel Gorman committed
163
	 "HighMem",
164
#endif
Mel Gorman's avatar
Mel Gorman committed
165
	 "Movable",
166 167
};

Linus Torvalds's avatar
Linus Torvalds committed
168 169
int min_free_kbytes = 1024;

170 171
static unsigned long __meminitdata nr_kernel_pages;
static unsigned long __meminitdata nr_all_pages;
172
static unsigned long __meminitdata dma_reserve;
Linus Torvalds's avatar
Linus Torvalds committed
173

174 175
#ifdef CONFIG_ARCH_POPULATES_NODE_MAP
  /*
Simon Arlott's avatar
Simon Arlott committed
176
   * MAX_ACTIVE_REGIONS determines the maximum number of distinct
177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194
   * 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

195 196 197 198
  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
199
  static unsigned long __initdata required_kernelcore;
200
  static unsigned long __initdata required_movablecore;
Adrian Bunk's avatar
Adrian Bunk committed
201
  static unsigned long __meminitdata zone_movable_pfn[MAX_NUMNODES];
Mel Gorman's avatar
Mel Gorman committed
202 203 204 205

  /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
  int movable_zone;
  EXPORT_SYMBOL(movable_zone);
206 207
#endif /* CONFIG_ARCH_POPULATES_NODE_MAP */

Miklos Szeredi's avatar
Miklos Szeredi committed
208 209
#if MAX_NUMNODES > 1
int nr_node_ids __read_mostly = MAX_NUMNODES;
210
int nr_online_nodes __read_mostly = 1;
Miklos Szeredi's avatar
Miklos Szeredi committed
211
EXPORT_SYMBOL(nr_node_ids);
212
EXPORT_SYMBOL(nr_online_nodes);
Miklos Szeredi's avatar
Miklos Szeredi committed
213 214
#endif

215 216
int page_group_by_mobility_disabled __read_mostly;

217 218
static void set_pageblock_migratetype(struct page *page, int migratetype)
{
219 220 221 222

	if (unlikely(page_group_by_mobility_disabled))
		migratetype = MIGRATE_UNMOVABLE;

223 224 225 226
	set_pageblock_flags_group(page, (unsigned long)migratetype,
					PB_migrate, PB_migrate_end);
}

227 228
bool oom_killer_disabled __read_mostly;

Nick Piggin's avatar
Nick Piggin committed
229
#ifdef CONFIG_DEBUG_VM
230
static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
231
{
232 233 234
	int ret = 0;
	unsigned seq;
	unsigned long pfn = page_to_pfn(page);
235

236 237 238 239 240 241 242 243 244
	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;
245 246 247 248
}

static int page_is_consistent(struct zone *zone, struct page *page)
{
249
	if (!pfn_valid_within(page_to_pfn(page)))
250
		return 0;
Linus Torvalds's avatar
Linus Torvalds committed
251
	if (zone != page_zone(page))
252 253 254 255 256 257 258 259 260 261
		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
262
		return 1;
263 264 265
	if (!page_is_consistent(zone, page))
		return 1;

Linus Torvalds's avatar
Linus Torvalds committed
266 267
	return 0;
}
Nick Piggin's avatar
Nick Piggin committed
268 269 270 271 272 273 274
#else
static inline int bad_range(struct zone *zone, struct page *page)
{
	return 0;
}
#endif

275
static void bad_page(struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
276
{
277 278 279 280
	static unsigned long resume;
	static unsigned long nr_shown;
	static unsigned long nr_unshown;

281 282 283 284 285 286
	/* Don't complain about poisoned pages */
	if (PageHWPoison(page)) {
		__ClearPageBuddy(page);
		return;
	}

287 288 289 290 291 292 293 294 295 296
	/*
	 * 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) {
297 298
			printk(KERN_ALERT
			      "BUG: Bad page state: %lu messages suppressed\n",
299 300 301 302 303 304 305 306
				nr_unshown);
			nr_unshown = 0;
		}
		nr_shown = 0;
	}
	if (nr_shown++ == 0)
		resume = jiffies + 60 * HZ;

307
	printk(KERN_ALERT "BUG: Bad page state in process %s  pfn:%05lx\n",
308
		current->comm, page_to_pfn(page));
309
	dump_page(page);
310

Linus Torvalds's avatar
Linus Torvalds committed
311
	dump_stack();
312
out:
313 314
	/* Leave bad fields for debug, except PageBuddy could make trouble */
	__ClearPageBuddy(page);
315
	add_taint(TAINT_BAD_PAGE);
Linus Torvalds's avatar
Linus Torvalds committed
316 317 318 319 320 321 322 323 324 325 326 327
}

/*
 * 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).
 *
328 329 330
 * 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
331
 */
332 333 334

static void free_compound_page(struct page *page)
{
335
	__free_pages_ok(page, compound_order(page));
336 337
}

338
void prep_compound_page(struct page *page, unsigned long order)
339 340 341 342 343 344 345 346 347 348 349 350 351 352 353
{
	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;
	}
}

354
static int destroy_compound_page(struct page *page, unsigned long order)
Linus Torvalds's avatar
Linus Torvalds committed
355 356 357
{
	int i;
	int nr_pages = 1 << order;
358
	int bad = 0;
Linus Torvalds's avatar
Linus Torvalds committed
359

360 361
	if (unlikely(compound_order(page) != order) ||
	    unlikely(!PageHead(page))) {
362
		bad_page(page);
363 364
		bad++;
	}
Linus Torvalds's avatar
Linus Torvalds committed
365

366
	__ClearPageHead(page);
367

368 369
	for (i = 1; i < nr_pages; i++) {
		struct page *p = page + i;
Linus Torvalds's avatar
Linus Torvalds committed
370

371
		if (unlikely(!PageTail(p) || (p->first_page != page))) {
372
			bad_page(page);
373 374
			bad++;
		}
375
		__ClearPageTail(p);
Linus Torvalds's avatar
Linus Torvalds committed
376
	}
377 378

	return bad;
Linus Torvalds's avatar
Linus Torvalds committed
379 380
}

Nick Piggin's avatar
Nick Piggin committed
381 382 383 384
static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags)
{
	int i;

385 386 387 388
	/*
	 * 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
389
	VM_BUG_ON((gfp_flags & __GFP_HIGHMEM) && in_interrupt());
Nick Piggin's avatar
Nick Piggin committed
390 391 392 393
	for (i = 0; i < (1 << order); i++)
		clear_highpage(page + i);
}

394 395
static inline void set_page_order(struct page *page, int order)
{
396
	set_page_private(page, order);
397
	__SetPageBuddy(page);
Linus Torvalds's avatar
Linus Torvalds committed
398 399 400 401
}

static inline void rmv_page_order(struct page *page)
{
402
	__ClearPageBuddy(page);
403
	set_page_private(page, 0);
Linus Torvalds's avatar
Linus Torvalds committed
404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420
}

/*
 * 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
421
 * Assumption: *_mem_map is contiguous at least up to MAX_ORDER
Linus Torvalds's avatar
Linus Torvalds committed
422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439
 */
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
440
 * (a) the buddy is not in a hole &&
441
 * (b) the buddy is in the buddy system &&
442 443
 * (c) a page and its buddy have the same order &&
 * (d) a page and its buddy are in the same zone.
444 445 446
 *
 * 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
447
 *
448
 * For recording page's order, we use page_private(page).
Linus Torvalds's avatar
Linus Torvalds committed
449
 */
450 451
static inline int page_is_buddy(struct page *page, struct page *buddy,
								int order)
Linus Torvalds's avatar
Linus Torvalds committed
452
{
453
	if (!pfn_valid_within(page_to_pfn(buddy)))
Nick Piggin's avatar
Nick Piggin committed
454 455
		return 0;

456 457 458 459
	if (page_zone_id(page) != page_zone_id(buddy))
		return 0;

	if (PageBuddy(buddy) && page_order(buddy) == order) {
460
		VM_BUG_ON(page_count(buddy) != 0);
461
		return 1;
462
	}
463
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
464 465 466 467 468 469 470 471 472 473 474 475 476 477 478
}

/*
 * 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
479
 * free pages of length of (1 << order) and marked with PG_buddy. Page's
480
 * order is recorded in page_private(page) field.
Linus Torvalds's avatar
Linus Torvalds committed
481 482 483 484 485 486 487 488 489
 * 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
490
static inline void __free_one_page(struct page *page,
491 492
		struct zone *zone, unsigned int order,
		int migratetype)
Linus Torvalds's avatar
Linus Torvalds committed
493 494
{
	unsigned long page_idx;
495 496
	unsigned long combined_idx;
	struct page *buddy;
Linus Torvalds's avatar
Linus Torvalds committed
497

498
	if (unlikely(PageCompound(page)))
499 500
		if (unlikely(destroy_compound_page(page, order)))
			return;
Linus Torvalds's avatar
Linus Torvalds committed
501

502 503
	VM_BUG_ON(migratetype == -1);

Linus Torvalds's avatar
Linus Torvalds committed
504 505
	page_idx = page_to_pfn(page) & ((1 << MAX_ORDER) - 1);

506
	VM_BUG_ON(page_idx & ((1 << order) - 1));
Nick Piggin's avatar
Nick Piggin committed
507
	VM_BUG_ON(bad_range(zone, page));
Linus Torvalds's avatar
Linus Torvalds committed
508 509 510

	while (order < MAX_ORDER-1) {
		buddy = __page_find_buddy(page, page_idx, order);
511
		if (!page_is_buddy(page, buddy, order))
512
			break;
Nick Piggin's avatar
Nick Piggin committed
513

514
		/* Our buddy is free, merge with it and move up one order. */
Linus Torvalds's avatar
Linus Torvalds committed
515
		list_del(&buddy->lru);
516
		zone->free_area[order].nr_free--;
Linus Torvalds's avatar
Linus Torvalds committed
517
		rmv_page_order(buddy);
Nick Piggin's avatar
Nick Piggin committed
518
		combined_idx = __find_combined_index(page_idx, order);
Linus Torvalds's avatar
Linus Torvalds committed
519 520 521 522 523
		page = page + (combined_idx - page_idx);
		page_idx = combined_idx;
		order++;
	}
	set_page_order(page, order);
524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546

	/*
	 * 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
547 548 549
	zone->free_area[order].nr_free++;
}

550 551 552 553 554 555 556 557 558 559 560
/*
 * 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);
}

561
static inline int free_pages_check(struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
562
{
Nick Piggin's avatar
Nick Piggin committed
563 564
	if (unlikely(page_mapcount(page) |
		(page->mapping != NULL)  |
565
		(atomic_read(&page->_count) != 0) |
566
		(page->flags & PAGE_FLAGS_CHECK_AT_FREE))) {
567
		bad_page(page);
568
		return 1;
569
	}
570 571 572
	if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
		page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
573 574 575
}

/*
576
 * Frees a number of pages from the PCP lists
Linus Torvalds's avatar
Linus Torvalds committed
577
 * Assumes all pages on list are in same zone, and of same order.
578
 * count is the number of pages to free.
Linus Torvalds's avatar
Linus Torvalds committed
579 580 581 582 583 584 585
 *
 * 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.
 */
586 587
static void free_pcppages_bulk(struct zone *zone, int count,
					struct per_cpu_pages *pcp)
Linus Torvalds's avatar
Linus Torvalds committed
588
{
589
	int migratetype = 0;
590
	int batch_free = 0;
591

Nick Piggin's avatar
Nick Piggin committed
592
	spin_lock(&zone->lock);
593
	zone->all_unreclaimable = 0;
Linus Torvalds's avatar
Linus Torvalds committed
594
	zone->pages_scanned = 0;
595

596
	__mod_zone_page_state(zone, NR_FREE_PAGES, count);
597
	while (count) {
Nick Piggin's avatar
Nick Piggin committed
598
		struct page *page;
599 600 601
		struct list_head *list;

		/*
602 603 604 605 606
		 * 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
607 608
		 */
		do {
609
			batch_free++;
610 611 612 613
			if (++migratetype == MIGRATE_PCPTYPES)
				migratetype = 0;
			list = &pcp->lists[migratetype];
		} while (list_empty(list));
Nick Piggin's avatar
Nick Piggin committed
614

615 616 617 618
		do {
			page = list_entry(list->prev, struct page, lru);
			/* must delete as __free_one_page list manipulates */
			list_del(&page->lru);
619 620 621
			/* 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));
622
		} while (--count && --batch_free && !list_empty(list));
Linus Torvalds's avatar
Linus Torvalds committed
623
	}
Nick Piggin's avatar
Nick Piggin committed
624
	spin_unlock(&zone->lock);
Linus Torvalds's avatar
Linus Torvalds committed
625 626
}

627 628
static void free_one_page(struct zone *zone, struct page *page, int order,
				int migratetype)
Linus Torvalds's avatar
Linus Torvalds committed
629
{
630
	spin_lock(&zone->lock);
631
	zone->all_unreclaimable = 0;
632
	zone->pages_scanned = 0;
633 634

	__mod_zone_page_state(zone, NR_FREE_PAGES, 1 << order);
635
	__free_one_page(page, zone, order, migratetype);
636
	spin_unlock(&zone->lock);
Nick Piggin's avatar
Nick Piggin committed
637 638
}

639
static bool free_pages_prepare(struct page *page, unsigned int order)
Nick Piggin's avatar
Nick Piggin committed
640
{
Linus Torvalds's avatar
Linus Torvalds committed
641
	int i;
642
	int bad = 0;
Linus Torvalds's avatar
Linus Torvalds committed
643

644
	trace_mm_page_free_direct(page, order);
645 646
	kmemcheck_free_shadow(page, order);

647 648 649 650 651 652 653
	for (i = 0; i < (1 << order); i++) {
		struct page *pg = page + i;

		if (PageAnon(pg))
			pg->mapping = NULL;
		bad += free_pages_check(pg);
	}
654
	if (bad)
655
		return false;
656

657
	if (!PageHighMem(page)) {
Nick Piggin's avatar
Nick Piggin committed
658
		debug_check_no_locks_freed(page_address(page),PAGE_SIZE<<order);
659 660 661
		debug_check_no_obj_freed(page_address(page),
					   PAGE_SIZE << order);
	}
Nick Piggin's avatar
Nick Piggin committed
662
	arch_free_page(page, order);
Nick Piggin's avatar
Nick Piggin committed
663
	kernel_map_pages(page, 1 << order, 0);
Nick Piggin's avatar
Nick Piggin committed
664

665 666 667 668 669 670 671 672 673 674 675
	return true;
}

static void __free_pages_ok(struct page *page, unsigned int order)
{
	unsigned long flags;
	int wasMlocked = __TestClearPageMlocked(page);

	if (!free_pages_prepare(page, order))
		return;

Nick Piggin's avatar
Nick Piggin committed
676
	local_irq_save(flags);
677
	if (unlikely(wasMlocked))
678
		free_page_mlock(page);
679
	__count_vm_events(PGFREE, 1 << order);
680 681
	free_one_page(page_zone(page), page, order,
					get_pageblock_migratetype(page));
Nick Piggin's avatar
Nick Piggin committed
682
	local_irq_restore(flags);
Linus Torvalds's avatar
Linus Torvalds committed
683 684
}

685 686 687
/*
 * permit the bootmem allocator to evade page validation on high-order frees
 */
688
void __meminit __free_pages_bootmem(struct page *page, unsigned int order)
689 690 691 692
{
	if (order == 0) {
		__ClearPageReserved(page);
		set_page_count(page, 0);
693
		set_page_refcounted(page);
Nick Piggin's avatar
Nick Piggin committed
694
		__free_page(page);
695 696 697
	} else {
		int loop;

Nick Piggin's avatar
Nick Piggin committed
698
		prefetchw(page);
699 700 701
		for (loop = 0; loop < BITS_PER_LONG; loop++) {
			struct page *p = &page[loop];

Nick Piggin's avatar
Nick Piggin committed
702 703
			if (loop + 1 < BITS_PER_LONG)
				prefetchw(p + 1);
704 705 706 707
			__ClearPageReserved(p);
			set_page_count(p, 0);
		}

708
		set_page_refcounted(page);
Nick Piggin's avatar
Nick Piggin committed
709
		__free_pages(page, order);
710 711 712
	}
}

Linus Torvalds's avatar
Linus Torvalds committed
713 714 715 716 717 718 719 720 721 722 723 724 725 726 727

/*
 * 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
728
static inline void expand(struct zone *zone, struct page *page,
729 730
	int low, int high, struct free_area *area,
	int migratetype)
Linus Torvalds's avatar
Linus Torvalds committed
731 732 733 734 735 736 737
{
	unsigned long size = 1 << high;

	while (high > low) {
		area--;
		high--;
		size >>= 1;
Nick Piggin's avatar
Nick Piggin committed
738
		VM_BUG_ON(bad_range(zone, &page[size]));
739
		list_add(&page[size].lru, &area->free_list[migratetype]);
Linus Torvalds's avatar
Linus Torvalds committed
740 741 742 743 744 745 746 747
		area->nr_free++;
		set_page_order(&page[size], high);
	}
}

/*
 * This page is about to be returned from the page allocator
 */
748
static inline int check_new_page(struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
749
{
Nick Piggin's avatar
Nick Piggin committed
750 751
	if (unlikely(page_mapcount(page) |
		(page->mapping != NULL)  |
752
		(atomic_read(&page->_count) != 0)  |
753
		(page->flags & PAGE_FLAGS_CHECK_AT_PREP))) {
754
		bad_page(page);
755
		return 1;
756
	}
757 758 759 760 761 762 763 764 765 766 767 768
	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;
	}
769

770
	set_page_private(page, 0);
771
	set_page_refcounted(page);
Nick Piggin's avatar
Nick Piggin committed
772 773

	arch_alloc_page(page, order);
Linus Torvalds's avatar
Linus Torvalds committed
774
	kernel_map_pages(page, 1 << order, 1);
Nick Piggin's avatar
Nick Piggin committed
775 776 777 778 779 780 781

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

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

782
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
783 784
}

785 786 787 788
/*
 * Go through the free lists for the given migratetype and remove
 * the smallest available page from the freelists
 */
789 790
static inline
struct page *__rmqueue_smallest(struct zone *zone, unsigned int order,
791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815
						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;
}


816 817 818 819 820
/*
 * 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] = {
821 822 823 824
	[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 */
825 826
};

827 828
/*
 * Move the free pages in a range to the free lists of the requested type.
829
 * Note that start_page and end_pages are not aligned on a pageblock
830 831
 * boundary. If alignment is required, use move_freepages_block()
 */
Adrian Bunk's avatar
Adrian Bunk committed
832 833 834
static int move_freepages(struct zone *zone,
			  struct page *start_page, struct page *end_page,
			  int migratetype)
835 836 837
{
	struct page *page;
	unsigned long order;
838
	int pages_moved = 0;
839 840 841 842 843 844 845

#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
846
	 * grouping pages by mobility
847 848 849 850 851
	 */
	BUG_ON(page_zone(start_page) != page_zone(end_page));
#endif

	for (page = start_page; page <= end_page;) {
852 853 854
		/* Make sure we are not inadvertently changing nodes */
		VM_BUG_ON(page_to_nid(page) != zone_to_nid(zone));

855 856 857 858 859 860 861 862 863 864 865 866 867 868 869
		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;
870
		pages_moved += 1 << order;
871 872
	}

873
	return pages_moved;
874 875
}

Adrian Bunk's avatar
Adrian Bunk committed
876 877
static int move_freepages_block(struct zone *zone, struct page *page,
				int migratetype)
878 879 880 881 882
{
	unsigned long start_pfn, end_pfn;
	struct page *start_page, *end_page;

	start_pfn = page_to_pfn(page);
883
	start_pfn = start_pfn & ~(pageblock_nr_pages-1);
884
	start_page = pfn_to_page(start_pfn);
885 886
	end_page = start_page + pageblock_nr_pages - 1;
	end_pfn = start_pfn + pageblock_nr_pages - 1;
887 888 889 890 891 892 893 894 895 896

	/* 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);
}

897 898 899 900 901 902 903 904 905 906 907
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;
	}
}

908
/* Remove an element from the buddy allocator from the fallback list */
909 910
static inline struct page *
__rmqueue_fallback(struct zone *zone, int order, int start_migratetype)
911 912 913 914 915 916 917 918 919 920 921 922
{
	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];

923 924 925
			/* MIGRATE_RESERVE handled later if necessary */
			if (migratetype == MIGRATE_RESERVE)
				continue;
926

927 928 929 930 931 932 933 934 935
			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--;

			/*
936
			 * If breaking a large block of pages, move all free
937 938 939
			 * pages to the preferred allocation list. If falling
			 * back for a reclaimable kernel allocation, be more
			 * agressive about taking ownership of free pages
940
			 */
941
			if (unlikely(current_order >= (pageblock_order >> 1)) ||
942 943
					start_migratetype == MIGRATE_RECLAIMABLE ||
					page_group_by_mobility_disabled) {
944 945 946 947 948
				unsigned long pages;
				pages = move_freepages_block(zone, page,
								start_migratetype);

				/* Claim the whole block if over half of it is free */
949 950
				if (pages >= (1 << (pageblock_order-1)) ||
						page_group_by_mobility_disabled)
951 952 953
					set_pageblock_migratetype(page,
								start_migratetype);

954
				migratetype = start_migratetype;
955
			}
956 957 958 959 960

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

961 962 963
			/* Take ownership for orders >= pageblock_order */
			if (current_order >= pageblock_order)
				change_pageblock_range(page, current_order,
964 965 966
							start_migratetype);

			expand(zone, page, order, current_order, area, migratetype);
967 968 969 970

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

971 972 973 974
			return page;
		}
	}

975
	return NULL;
976 977
}

978
/*
Linus Torvalds's avatar
Linus Torvalds committed
979 980 981
 * Do the hard work of removing an element from the buddy allocator.
 * Call me with the zone->lock already held.
 */
982 983
static struct page *__rmqueue(struct zone *zone, unsigned int order,
						int migratetype)
Linus Torvalds's avatar
Linus Torvalds committed
984 985 986
{
	struct page *page;

987
retry_reserve:
988
	page = __rmqueue_smallest(zone, order, migratetype);
989

990
	if (unlikely(!page) && migratetype != MIGRATE_RESERVE) {
991
		page = __rmqueue_fallback(zone, order, migratetype);
992

993 994 995 996 997 998 999 1000 1001