page_alloc.c 192 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
/*
 *  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>
21
#include <linux/rwsem.h>
Linus Torvalds's avatar
Linus Torvalds committed
22
#include <linux/pagemap.h>
23
#include <linux/jiffies.h>
Linus Torvalds's avatar
Linus Torvalds committed
24
#include <linux/bootmem.h>
25
#include <linux/memblock.h>
Linus Torvalds's avatar
Linus Torvalds committed
26
#include <linux/compiler.h>
27
#include <linux/kernel.h>
28
#include <linux/kmemcheck.h>
29
#include <linux/kasan.h>
Linus Torvalds's avatar
Linus Torvalds committed
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>
35
#include <linux/ratelimit.h>
36
#include <linux/oom.h>
Linus Torvalds's avatar
Linus Torvalds committed
37 38 39 40 41
#include <linux/notifier.h>
#include <linux/topology.h>
#include <linux/sysctl.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
42
#include <linux/memory_hotplug.h>
Linus Torvalds's avatar
Linus Torvalds committed
43 44
#include <linux/nodemask.h>
#include <linux/vmalloc.h>
45
#include <linux/vmstat.h>
46
#include <linux/mempolicy.h>
47
#include <linux/stop_machine.h>
48 49
#include <linux/sort.h>
#include <linux/pfn.h>
50
#include <linux/backing-dev.h>
51
#include <linux/fault-inject.h>
52
#include <linux/page-isolation.h>
53
#include <linux/page_ext.h>
54
#include <linux/debugobjects.h>
55
#include <linux/kmemleak.h>
56
#include <linux/compaction.h>
57
#include <trace/events/kmem.h>
58
#include <linux/prefetch.h>
59
#include <linux/mm_inline.h>
60
#include <linux/migrate.h>
61
#include <linux/page_ext.h>
62
#include <linux/hugetlb.h>
63
#include <linux/sched/rt.h>
64
#include <linux/page_owner.h>
65
#include <linux/kthread.h>
Linus Torvalds's avatar
Linus Torvalds committed
66

67
#include <asm/sections.h>
Linus Torvalds's avatar
Linus Torvalds committed
68
#include <asm/tlbflush.h>
69
#include <asm/div64.h>
Linus Torvalds's avatar
Linus Torvalds committed
70 71
#include "internal.h"

72 73
/* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */
static DEFINE_MUTEX(pcp_batch_high_lock);
74
#define MIN_PERCPU_PAGELIST_FRACTION	(8)
75

76 77 78 79 80
#ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
DEFINE_PER_CPU(int, numa_node);
EXPORT_PER_CPU_SYMBOL(numa_node);
#endif

81 82 83 84 85 86 87 88 89
#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_);
90
int _node_numa_mem_[MAX_NUMNODES];
91 92
#endif

Linus Torvalds's avatar
Linus Torvalds committed
93
/*
94
 * Array of node states.
Linus Torvalds's avatar
Linus Torvalds committed
95
 */
96 97 98 99 100 101 102
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 } },
103 104 105
#endif
#ifdef CONFIG_MOVABLE_NODE
	[N_MEMORY] = { { [0] = 1UL } },
106 107 108 109 110 111
#endif
	[N_CPU] = { { [0] = 1UL } },
#endif	/* NUMA */
};
EXPORT_SYMBOL(node_states);

112 113 114
/* Protect totalram_pages and zone->managed_pages */
static DEFINE_SPINLOCK(managed_page_count_lock);

115
unsigned long totalram_pages __read_mostly;
116
unsigned long totalreserve_pages __read_mostly;
117
unsigned long totalcma_pages __read_mostly;
118 119 120 121 122 123 124 125
/*
 * When calculating the number of globally allowed dirty pages, there
 * is a certain number of per-zone reserves that should not be
 * considered dirtyable memory.  This is the sum of those reserves
 * over all existing zones that contribute dirtyable memory.
 */
unsigned long dirty_balance_reserve __read_mostly;

126
int percpu_pagelist_fraction;
127
gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
Linus Torvalds's avatar
Linus Torvalds committed
128

129 130 131 132 133 134 135 136 137
#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).
 */
138 139 140 141

static gfp_t saved_gfp_mask;

void pm_restore_gfp_mask(void)
142 143
{
	WARN_ON(!mutex_is_locked(&pm_mutex));
144 145 146 147
	if (saved_gfp_mask) {
		gfp_allowed_mask = saved_gfp_mask;
		saved_gfp_mask = 0;
	}
148 149
}

150
void pm_restrict_gfp_mask(void)
151 152
{
	WARN_ON(!mutex_is_locked(&pm_mutex));
153 154 155
	WARN_ON(saved_gfp_mask);
	saved_gfp_mask = gfp_allowed_mask;
	gfp_allowed_mask &= ~GFP_IOFS;
156
}
157 158 159 160 161 162 163

bool pm_suspended_storage(void)
{
	if ((gfp_allowed_mask & GFP_IOFS) == GFP_IOFS)
		return false;
	return true;
}
164 165
#endif /* CONFIG_PM_SLEEP */

166 167 168 169
#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
int pageblock_order __read_mostly;
#endif

170
static void __free_pages_ok(struct page *page, unsigned int order);
171

Linus Torvalds's avatar
Linus Torvalds committed
172 173 174 175 176 177
/*
 * 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
Yaowei Bai's avatar
Yaowei Bai committed
178
 *	HIGHMEM allocation will leave (224M+784M)/256 of ram reserved in ZONE_DMA
179 180 181
 *
 * 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
182
 */
183
int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
184
#ifdef CONFIG_ZONE_DMA
185
	 256,
186
#endif
187
#ifdef CONFIG_ZONE_DMA32
188
	 256,
189
#endif
190
#ifdef CONFIG_HIGHMEM
Mel Gorman's avatar
Mel Gorman committed
191
	 32,
192
#endif
Mel Gorman's avatar
Mel Gorman committed
193
	 32,
194
};
Linus Torvalds's avatar
Linus Torvalds committed
195 196 197

EXPORT_SYMBOL(totalram_pages);

198
static char * const zone_names[MAX_NR_ZONES] = {
199
#ifdef CONFIG_ZONE_DMA
200
	 "DMA",
201
#endif
202
#ifdef CONFIG_ZONE_DMA32
203
	 "DMA32",
204
#endif
205
	 "Normal",
206
#ifdef CONFIG_HIGHMEM
Mel Gorman's avatar
Mel Gorman committed
207
	 "HighMem",
208
#endif
Mel Gorman's avatar
Mel Gorman committed
209
	 "Movable",
210 211
};

Linus Torvalds's avatar
Linus Torvalds committed
212
int min_free_kbytes = 1024;
213
int user_min_free_kbytes = -1;
Linus Torvalds's avatar
Linus Torvalds committed
214

215 216
static unsigned long __meminitdata nr_kernel_pages;
static unsigned long __meminitdata nr_all_pages;
217
static unsigned long __meminitdata dma_reserve;
Linus Torvalds's avatar
Linus Torvalds committed
218

Tejun Heo's avatar
Tejun Heo committed
219 220 221 222 223 224 225 226 227 228 229
#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
static unsigned long __meminitdata arch_zone_lowest_possible_pfn[MAX_NR_ZONES];
static unsigned long __meminitdata arch_zone_highest_possible_pfn[MAX_NR_ZONES];
static unsigned long __initdata required_kernelcore;
static unsigned long __initdata required_movablecore;
static unsigned long __meminitdata 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);
#endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
230

Miklos Szeredi's avatar
Miklos Szeredi committed
231 232
#if MAX_NUMNODES > 1
int nr_node_ids __read_mostly = MAX_NUMNODES;
233
int nr_online_nodes __read_mostly = 1;
Miklos Szeredi's avatar
Miklos Szeredi committed
234
EXPORT_SYMBOL(nr_node_ids);
235
EXPORT_SYMBOL(nr_online_nodes);
Miklos Szeredi's avatar
Miklos Szeredi committed
236 237
#endif

238 239
int page_group_by_mobility_disabled __read_mostly;

240 241 242 243 244 245 246
#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
static inline void reset_deferred_meminit(pg_data_t *pgdat)
{
	pgdat->first_deferred_pfn = ULONG_MAX;
}

/* Returns true if the struct page for the pfn is uninitialised */
247
static inline bool __meminit early_page_uninitialised(unsigned long pfn)
248
{
249
	if (pfn >= NODE_DATA(early_pfn_to_nid(pfn))->first_deferred_pfn)
250 251 252 253 254
		return true;

	return false;
}

255 256 257 258 259 260 261 262
static inline bool early_page_nid_uninitialised(unsigned long pfn, int nid)
{
	if (pfn >= NODE_DATA(nid)->first_deferred_pfn)
		return true;

	return false;
}

263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294
/*
 * Returns false when the remaining initialisation should be deferred until
 * later in the boot cycle when it can be parallelised.
 */
static inline bool update_defer_init(pg_data_t *pgdat,
				unsigned long pfn, unsigned long zone_end,
				unsigned long *nr_initialised)
{
	/* Always populate low zones for address-contrained allocations */
	if (zone_end < pgdat_end_pfn(pgdat))
		return true;

	/* Initialise at least 2G of the highest zone */
	(*nr_initialised)++;
	if (*nr_initialised > (2UL << (30 - PAGE_SHIFT)) &&
	    (pfn & (PAGES_PER_SECTION - 1)) == 0) {
		pgdat->first_deferred_pfn = pfn;
		return false;
	}

	return true;
}
#else
static inline void reset_deferred_meminit(pg_data_t *pgdat)
{
}

static inline bool early_page_uninitialised(unsigned long pfn)
{
	return false;
}

295 296 297 298 299
static inline bool early_page_nid_uninitialised(unsigned long pfn, int nid)
{
	return false;
}

300 301 302 303 304 305 306 307 308
static inline bool update_defer_init(pg_data_t *pgdat,
				unsigned long pfn, unsigned long zone_end,
				unsigned long *nr_initialised)
{
	return true;
}
#endif


309
void set_pageblock_migratetype(struct page *page, int migratetype)
310
{
311 312
	if (unlikely(page_group_by_mobility_disabled &&
		     migratetype < MIGRATE_PCPTYPES))
313 314
		migratetype = MIGRATE_UNMOVABLE;

315 316 317 318
	set_pageblock_flags_group(page, (unsigned long)migratetype,
					PB_migrate, PB_migrate_end);
}

Nick Piggin's avatar
Nick Piggin committed
319
#ifdef CONFIG_DEBUG_VM
320
static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
321
{
322 323 324
	int ret = 0;
	unsigned seq;
	unsigned long pfn = page_to_pfn(page);
325
	unsigned long sp, start_pfn;
326

327 328
	do {
		seq = zone_span_seqbegin(zone);
329 330
		start_pfn = zone->zone_start_pfn;
		sp = zone->spanned_pages;
331
		if (!zone_spans_pfn(zone, pfn))
332 333 334
			ret = 1;
	} while (zone_span_seqretry(zone, seq));

335
	if (ret)
336 337 338
		pr_err("page 0x%lx outside node %d zone %s [ 0x%lx - 0x%lx ]\n",
			pfn, zone_to_nid(zone), zone->name,
			start_pfn, start_pfn + sp);
339

340
	return ret;
341 342 343 344
}

static int page_is_consistent(struct zone *zone, struct page *page)
{
345
	if (!pfn_valid_within(page_to_pfn(page)))
346
		return 0;
Linus Torvalds's avatar
Linus Torvalds committed
347
	if (zone != page_zone(page))
348 349 350 351 352 353 354 355 356 357
		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
358
		return 1;
359 360 361
	if (!page_is_consistent(zone, page))
		return 1;

Linus Torvalds's avatar
Linus Torvalds committed
362 363
	return 0;
}
Nick Piggin's avatar
Nick Piggin committed
364 365 366 367 368 369 370
#else
static inline int bad_range(struct zone *zone, struct page *page)
{
	return 0;
}
#endif

371 372
static void bad_page(struct page *page, const char *reason,
		unsigned long bad_flags)
Linus Torvalds's avatar
Linus Torvalds committed
373
{
374 375 376 377
	static unsigned long resume;
	static unsigned long nr_shown;
	static unsigned long nr_unshown;

378 379
	/* Don't complain about poisoned pages */
	if (PageHWPoison(page)) {
380
		page_mapcount_reset(page); /* remove PageBuddy */
381 382 383
		return;
	}

384 385 386 387 388 389 390 391 392 393
	/*
	 * 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) {
394 395
			printk(KERN_ALERT
			      "BUG: Bad page state: %lu messages suppressed\n",
396 397 398 399 400 401 402 403
				nr_unshown);
			nr_unshown = 0;
		}
		nr_shown = 0;
	}
	if (nr_shown++ == 0)
		resume = jiffies + 60 * HZ;

404
	printk(KERN_ALERT "BUG: Bad page state in process %s  pfn:%05lx\n",
405
		current->comm, page_to_pfn(page));
406
	dump_page_badflags(page, reason, bad_flags);
407

408
	print_modules();
Linus Torvalds's avatar
Linus Torvalds committed
409
	dump_stack();
410
out:
411
	/* Leave bad fields for debug, except PageBuddy could make trouble */
412
	page_mapcount_reset(page); /* remove PageBuddy */
413
	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
Linus Torvalds's avatar
Linus Torvalds committed
414 415 416 417 418 419 420 421 422
}

/*
 * 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".
 *
423 424
 * All pages have PG_compound set.  All tail pages have their ->first_page
 * pointing at the head page.
Linus Torvalds's avatar
Linus Torvalds committed
425
 *
426 427 428
 * 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
429
 */
430 431 432

static void free_compound_page(struct page *page)
{
433
	__free_pages_ok(page, compound_order(page));
434 435
}

436
void prep_compound_page(struct page *page, unsigned long order)
437 438 439 440 441 442 443 444 445
{
	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;
446
		set_page_count(p, 0);
447
		p->first_page = page;
David Rientjes's avatar
David Rientjes committed
448 449 450
		/* Make sure p->first_page is always valid for PageTail() */
		smp_wmb();
		__SetPageTail(p);
451 452 453
	}
}

454 455
#ifdef CONFIG_DEBUG_PAGEALLOC
unsigned int _debug_guardpage_minorder;
456
bool _debug_pagealloc_enabled __read_mostly;
457 458
bool _debug_guardpage_enabled __read_mostly;

459 460 461 462 463 464 465 466 467 468 469 470
static int __init early_debug_pagealloc(char *buf)
{
	if (!buf)
		return -EINVAL;

	if (strcmp(buf, "on") == 0)
		_debug_pagealloc_enabled = true;

	return 0;
}
early_param("debug_pagealloc", early_debug_pagealloc);

471 472
static bool need_debug_guardpage(void)
{
473 474 475 476
	/* If we don't use debug_pagealloc, we don't need guard page */
	if (!debug_pagealloc_enabled())
		return false;

477 478 479 480 481
	return true;
}

static void init_debug_guardpage(void)
{
482 483 484
	if (!debug_pagealloc_enabled())
		return;

485 486 487 488 489 490 491
	_debug_guardpage_enabled = true;
}

struct page_ext_operations debug_guardpage_ops = {
	.need = need_debug_guardpage,
	.init = init_debug_guardpage,
};
492 493 494 495 496 497 498 499 500 501 502 503 504 505 506

static int __init debug_guardpage_minorder_setup(char *buf)
{
	unsigned long res;

	if (kstrtoul(buf, 10, &res) < 0 ||  res > MAX_ORDER / 2) {
		printk(KERN_ERR "Bad debug_guardpage_minorder value\n");
		return 0;
	}
	_debug_guardpage_minorder = res;
	printk(KERN_INFO "Setting debug_guardpage_minorder to %lu\n", res);
	return 0;
}
__setup("debug_guardpage_minorder=", debug_guardpage_minorder_setup);

507 508
static inline void set_page_guard(struct zone *zone, struct page *page,
				unsigned int order, int migratetype)
509
{
510 511 512 513 514 515 516 517
	struct page_ext *page_ext;

	if (!debug_guardpage_enabled())
		return;

	page_ext = lookup_page_ext(page);
	__set_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);

518 519 520 521
	INIT_LIST_HEAD(&page->lru);
	set_page_private(page, order);
	/* Guard pages are not available for any usage */
	__mod_zone_freepage_state(zone, -(1 << order), migratetype);
522 523
}

524 525
static inline void clear_page_guard(struct zone *zone, struct page *page,
				unsigned int order, int migratetype)
526
{
527 528 529 530 531 532 533 534
	struct page_ext *page_ext;

	if (!debug_guardpage_enabled())
		return;

	page_ext = lookup_page_ext(page);
	__clear_bit(PAGE_EXT_DEBUG_GUARD, &page_ext->flags);

535 536 537
	set_page_private(page, 0);
	if (!is_migrate_isolate(migratetype))
		__mod_zone_freepage_state(zone, (1 << order), migratetype);
538 539
}
#else
540
struct page_ext_operations debug_guardpage_ops = { NULL, };
541 542 543 544
static inline void set_page_guard(struct zone *zone, struct page *page,
				unsigned int order, int migratetype) {}
static inline void clear_page_guard(struct zone *zone, struct page *page,
				unsigned int order, int migratetype) {}
545 546
#endif

547
static inline void set_page_order(struct page *page, unsigned int order)
548
{
549
	set_page_private(page, order);
550
	__SetPageBuddy(page);
Linus Torvalds's avatar
Linus Torvalds committed
551 552 553 554
}

static inline void rmv_page_order(struct page *page)
{
555
	__ClearPageBuddy(page);
556
	set_page_private(page, 0);
Linus Torvalds's avatar
Linus Torvalds committed
557 558 559 560 561
}

/*
 * 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
562
 * (a) the buddy is not in a hole &&
563
 * (b) the buddy is in the buddy system &&
564 565
 * (c) a page and its buddy have the same order &&
 * (d) a page and its buddy are in the same zone.
566
 *
567 568 569 570
 * For recording whether a page is in the buddy system, we set ->_mapcount
 * PAGE_BUDDY_MAPCOUNT_VALUE.
 * Setting, clearing, and testing _mapcount PAGE_BUDDY_MAPCOUNT_VALUE is
 * serialized by zone->lock.
Linus Torvalds's avatar
Linus Torvalds committed
571
 *
572
 * For recording page's order, we use page_private(page).
Linus Torvalds's avatar
Linus Torvalds committed
573
 */
574
static inline int page_is_buddy(struct page *page, struct page *buddy,
575
							unsigned int order)
Linus Torvalds's avatar
Linus Torvalds committed
576
{
577
	if (!pfn_valid_within(page_to_pfn(buddy)))
Nick Piggin's avatar
Nick Piggin committed
578 579
		return 0;

580
	if (page_is_guard(buddy) && page_order(buddy) == order) {
581 582 583
		if (page_zone_id(page) != page_zone_id(buddy))
			return 0;

584 585
		VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);

586 587 588
		return 1;
	}

589
	if (PageBuddy(buddy) && page_order(buddy) == order) {
590 591 592 593 594 595 596 597
		/*
		 * zone check is done late to avoid uselessly
		 * calculating zone/node ids for pages that could
		 * never merge.
		 */
		if (page_zone_id(page) != page_zone_id(buddy))
			return 0;

598 599
		VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);

600
		return 1;
601
	}
602
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
603 604 605 606 607 608 609 610 611 612 613 614 615 616 617
}

/*
 * 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
618 619 620
 * free pages of length of (1 << order) and marked with _mapcount
 * PAGE_BUDDY_MAPCOUNT_VALUE. Page's order is recorded in page_private(page)
 * field.
Linus Torvalds's avatar
Linus Torvalds committed
621
 * So when we are allocating or freeing one, we can derive the state of the
622 623
 * other.  That is, if we allocate a small block, and both were
 * free, the remainder of the region must be split into blocks.
Linus Torvalds's avatar
Linus Torvalds committed
624
 * If a block is freed, and its buddy is also free, then this
625
 * triggers coalescing into a block of larger size.
Linus Torvalds's avatar
Linus Torvalds committed
626
 *
627
 * -- nyc
Linus Torvalds's avatar
Linus Torvalds committed
628 629
 */

Nick Piggin's avatar
Nick Piggin committed
630
static inline void __free_one_page(struct page *page,
631
		unsigned long pfn,
632 633
		struct zone *zone, unsigned int order,
		int migratetype)
Linus Torvalds's avatar
Linus Torvalds committed
634 635
{
	unsigned long page_idx;
636
	unsigned long combined_idx;
637
	unsigned long uninitialized_var(buddy_idx);
638
	struct page *buddy;
639
	int max_order = MAX_ORDER;
Linus Torvalds's avatar
Linus Torvalds committed
640

641
	VM_BUG_ON(!zone_is_initialized(zone));
642
	VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page);
Linus Torvalds's avatar
Linus Torvalds committed
643

644
	VM_BUG_ON(migratetype == -1);
645 646 647 648 649 650 651 652 653
	if (is_migrate_isolate(migratetype)) {
		/*
		 * We restrict max order of merging to prevent merge
		 * between freepages on isolate pageblock and normal
		 * pageblock. Without this, pageblock isolation
		 * could cause incorrect freepage accounting.
		 */
		max_order = min(MAX_ORDER, pageblock_order + 1);
	} else {
654
		__mod_zone_freepage_state(zone, 1 << order, migratetype);
655
	}
656

657
	page_idx = pfn & ((1 << max_order) - 1);
Linus Torvalds's avatar
Linus Torvalds committed
658

659 660
	VM_BUG_ON_PAGE(page_idx & ((1 << order) - 1), page);
	VM_BUG_ON_PAGE(bad_range(zone, page), page);
Linus Torvalds's avatar
Linus Torvalds committed
661

662
	while (order < max_order - 1) {
663 664
		buddy_idx = __find_buddy_index(page_idx, order);
		buddy = page + (buddy_idx - page_idx);
665
		if (!page_is_buddy(page, buddy, order))
666
			break;
667 668 669 670 671
		/*
		 * Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,
		 * merge with it and move up one order.
		 */
		if (page_is_guard(buddy)) {
672
			clear_page_guard(zone, buddy, order, migratetype);
673 674 675 676 677
		} else {
			list_del(&buddy->lru);
			zone->free_area[order].nr_free--;
			rmv_page_order(buddy);
		}
678
		combined_idx = buddy_idx & page_idx;
Linus Torvalds's avatar
Linus Torvalds committed
679 680 681 682 683
		page = page + (combined_idx - page_idx);
		page_idx = combined_idx;
		order++;
	}
	set_page_order(page, order);
684 685 686 687 688 689 690 691 692

	/*
	 * 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
	 */
693
	if ((order < MAX_ORDER-2) && pfn_valid_within(page_to_pfn(buddy))) {
694
		struct page *higher_page, *higher_buddy;
695 696 697
		combined_idx = buddy_idx & page_idx;
		higher_page = page + (combined_idx - page_idx);
		buddy_idx = __find_buddy_index(combined_idx, order + 1);
698
		higher_buddy = higher_page + (buddy_idx - combined_idx);
699 700 701 702 703 704 705 706 707
		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
708 709 710
	zone->free_area[order].nr_free++;
}

711
static inline int free_pages_check(struct page *page)
Linus Torvalds's avatar
Linus Torvalds committed
712
{
713
	const char *bad_reason = NULL;
714 715 716 717 718 719 720 721 722 723 724 725
	unsigned long bad_flags = 0;

	if (unlikely(page_mapcount(page)))
		bad_reason = "nonzero mapcount";
	if (unlikely(page->mapping != NULL))
		bad_reason = "non-NULL mapping";
	if (unlikely(atomic_read(&page->_count) != 0))
		bad_reason = "nonzero _count";
	if (unlikely(page->flags & PAGE_FLAGS_CHECK_AT_FREE)) {
		bad_reason = "PAGE_FLAGS_CHECK_AT_FREE flag(s) set";
		bad_flags = PAGE_FLAGS_CHECK_AT_FREE;
	}
726 727 728 729
#ifdef CONFIG_MEMCG
	if (unlikely(page->mem_cgroup))
		bad_reason = "page still charged to cgroup";
#endif
730 731
	if (unlikely(bad_reason)) {
		bad_page(page, bad_reason, bad_flags);
732
		return 1;
733
	}
734
	page_cpupid_reset_last(page);
735 736 737
	if (page->flags & PAGE_FLAGS_CHECK_AT_PREP)
		page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
	return 0;
Linus Torvalds's avatar
Linus Torvalds committed
738 739 740
}

/*
741
 * Frees a number of pages from the PCP lists
Linus Torvalds's avatar
Linus Torvalds committed
742
 * Assumes all pages on list are in same zone, and of same order.
743
 * count is the number of pages to free.
Linus Torvalds's avatar
Linus Torvalds committed
744 745 746 747 748 749 750
 *
 * 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.
 */
751 752
static void free_pcppages_bulk(struct zone *zone, int count,
					struct per_cpu_pages *pcp)
Linus Torvalds's avatar
Linus Torvalds committed
753
{
754
	int migratetype = 0;
755
	int batch_free = 0;
756
	int to_free = count;
757
	unsigned long nr_scanned;
758

Nick Piggin's avatar
Nick Piggin committed
759
	spin_lock(&zone->lock);
760 761 762
	nr_scanned = zone_page_state(zone, NR_PAGES_SCANNED);
	if (nr_scanned)
		__mod_zone_page_state(zone, NR_PAGES_SCANNED, -nr_scanned);
763

764
	while (to_free) {
Nick Piggin's avatar
Nick Piggin committed
765
		struct page *page;
766 767 768
		struct list_head *list;

		/*
769 770 771 772 773
		 * 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
774 775
		 */
		do {
776
			batch_free++;
777 778 779 780
			if (++migratetype == MIGRATE_PCPTYPES)
				migratetype = 0;
			list = &pcp->lists[migratetype];
		} while (list_empty(list));
Nick Piggin's avatar
Nick Piggin committed
781

782 783 784 785
		/* This is the only non-empty list. Free them all. */
		if (batch_free == MIGRATE_PCPTYPES)
			batch_free = to_free;

786
		do {
787 788
			int mt;	/* migratetype of the to-be-freed page */

789 790 791
			page = list_entry(list->prev, struct page, lru);
			/* must delete as __free_one_page list manipulates */
			list_del(&page->lru);
792
			mt = get_freepage_migratetype(page);
793
			if (unlikely(has_isolate_pageblock(zone)))
794 795
				mt = get_pageblock_migratetype(page);

796
			/* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */
797
			__free_one_page(page, page_to_pfn(page), zone, 0, mt);
798
			trace_mm_page_pcpu_drain(page, 0, mt);
799
		} while (--to_free && --batch_free && !list_empty(list));
Linus Torvalds's avatar
Linus Torvalds committed
800
	}
Nick Piggin's avatar
Nick Piggin committed
801
	spin_unlock(&zone->lock);
Linus Torvalds's avatar
Linus Torvalds committed
802 803
}

804 805
static void free_one_page(struct zone *zone,
				struct page *page, unsigned long pfn,
806
				unsigned int order,
807
				int migratetype)
Linus Torvalds's avatar
Linus Torvalds committed
808
{
809
	unsigned long nr_scanned;
810
	spin_lock(&zone->lock);
811 812 813
	nr_scanned = zone_page_state(zone, NR_PAGES_SCANNED);
	if (nr_scanned)
		__mod_zone_page_state(zone, NR_PAGES_SCANNED, -nr_scanned);
814

815 816 817 818
	if (unlikely(has_isolate_pageblock(zone) ||
		is_migrate_isolate(migratetype))) {
		migratetype = get_pfnblock_migratetype(page, pfn);
	}
819
	__free_one_page(page, pfn, zone, order, migratetype);
820
	spin_unlock(&zone->lock);
Nick Piggin's avatar
Nick Piggin committed
821 822
}

823 824 825 826 827 828 829 830 831 832 833 834 835 836 837
static int free_tail_pages_check(struct page *head_page, struct page *page)
{
	if (!IS_ENABLED(CONFIG_DEBUG_VM))
		return 0;
	if (unlikely(!PageTail(page))) {
		bad_page(page, "PageTail not set", 0);
		return 1;
	}
	if (unlikely(page->first_page != head_page)) {
		bad_page(page, "first_page not consistent", 0);
		return 1;
	}
	return 0;
}

838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859
static void __meminit __init_single_page(struct page *page, unsigned long pfn,
				unsigned long zone, int nid)
{
	set_page_links(page, zone, nid, pfn);
	init_page_count(page);
	page_mapcount_reset(page);
	page_cpupid_reset_last(page);

	INIT_LIST_HEAD(&page->lru);
#ifdef WANT_PAGE_VIRTUAL
	/* The shift won't overflow because ZONE_NORMAL is below 4G. */
	if (!is_highmem_idx(zone))
		set_page_address(page, __va(pfn << PAGE_SHIFT));
#endif
}

static void __meminit __init_single_pfn(unsigned long pfn, unsigned long zone,
					int nid)
{
	return __init_single_page(pfn_to_page(pfn), pfn, zone, nid);
}

860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885
#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
static void init_reserved_page(unsigned long pfn)
{
	pg_data_t *pgdat;
	int nid, zid;

	if (!early_page_uninitialised(pfn))
		return;

	nid = early_pfn_to_nid(pfn);
	pgdat = NODE_DATA(nid);

	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
		struct zone *zone = &pgdat->node_zones[zid];

		if (pfn >= zone->zone_start_pfn && pfn < zone_end_pfn(zone))
			break;
	}
	__init_single_pfn(pfn, zid, nid);
}
#else
static inline void init_reserved_page(unsigned long pfn)
{
}
#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */

886 887 888 889 890 891
/*
 * Initialised pages do not have PageReserved set. This function is
 * called for each range allocated by the bootmem allocator and
 * marks the pages PageReserved. The remaining valid pages are later
 * sent to the buddy page allocator.
 */
892
void __meminit reserve_bootmem_region(unsigned long start, unsigned long end)
893 894 895 896
{
	unsigned long start_pfn = PFN_DOWN(start);
	unsigned long end_pfn = PFN_UP(end);

897 898 899 900 901 902 903 904
	for (; start_pfn < end_pfn; start_pfn++) {
		if (pfn_valid(start_pfn)) {
			struct page *page = pfn_to_page(start_pfn);

			init_reserved_page(start_pfn);
			SetPageReserved(page);
		}
	}
905 906
}

907
static bool free_pages_prepare(struct page *page, unsigned int order)
Nick Piggin's avatar
Nick Piggin committed
908
{
909 910
	bool compound = PageCompound(page);
	int i, bad = 0;
Linus Torvalds's avatar
Linus Torvalds committed
911

912
	VM_BUG_ON_PAGE(PageTail(page), page);
913
	VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
914

915
	trace_mm_page_free(page, order);
916
	kmemcheck_free_shadow(page, order);
917
	kasan_free_pages(page, order);
918

Andrea Arcangeli's avatar
Andrea Arcangeli committed
919 920
	if (PageAnon(page))
		page->mapping = NULL;
921 922 923 924
	bad += free_pages_check(page);
	for (i = 1; i < (1 << order); i++) {
		if (compound)
			bad += free_tail_pages_check(page, page + i);
Andrea Arcangeli's avatar
Andrea Arcangeli committed
925
		bad += free_pages_check(page + i);
926
	}
927
	if (bad)
928
		return false;
929

930 931
	reset_page_owner(page, order);

932
	if (!PageHighMem(page)) {
933 934
		debug_check_no_locks_freed(page_address(page),
					   PAGE_SIZE << order);
935 936 937
		debug_check_no_obj_freed(page_address(page),
					   PAGE_SIZE << order);
	}
Nick Piggin's avatar
Nick Piggin committed
938
	arch_free_page(page, order);
Nick Piggin's avatar
Nick Piggin committed
939
	kernel_map_pages(page, 1 << order, 0);
Nick Piggin's avatar
Nick Piggin committed
940

941 942 943 944 945 946
	return true;
}

static void __free_pages_ok(struct page *page, unsigned int order)
{
	unsigned long flags;
947
	int migratetype;
948
	unsigned long pfn = page_to_pfn(page);
949