summaryrefslogtreecommitdiffstats
path: root/include/linux/page-flags.h
blob: e5a32445f930d71d611098fc1e5c7dc1351c166d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
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
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
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
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
/*
 * Macros for manipulating and testing page->flags
 */

#ifndef PAGE_FLAGS_H
#define PAGE_FLAGS_H

#include <linux/types.h>
#include <linux/bug.h>
#include <linux/mmdebug.h>
#ifndef __GENERATING_BOUNDS_H
#include <linux/mm_types.h>
#include <generated/bounds.h>
#endif /* !__GENERATING_BOUNDS_H */

/*
 * Various page->flags bits:
 *
 * PG_reserved is set for special pages, which can never be swapped out. Some
 * of them might not even exist (eg empty_bad_page)...
 *
 * The PG_private bitflag is set on pagecache pages if they contain filesystem
 * specific data (which is normally at page->private). It can be used by
 * private allocations for its own usage.
 *
 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O
 * and cleared when writeback _starts_ or when read _completes_. PG_writeback
 * is set before writeback starts and cleared when it finishes.
 *
 * PG_locked also pins a page in pagecache, and blocks truncation of the file
 * while it is held.
 *
 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
 * to become unlocked.
 *
 * PG_uptodate tells whether the page's contents is valid.  When a read
 * completes, the page becomes uptodate, unless a disk I/O error happened.
 *
 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
 * file-backed pagecache (see mm/vmscan.c).
 *
 * PG_error is set to indicate that an I/O error occurred on this page.
 *
 * PG_arch_1 is an architecture specific page state bit.  The generic code
 * guarantees that this bit is cleared for a page when it first is entered into
 * the page cache.
 *
 * PG_highmem pages are not permanently mapped into the kernel virtual address
 * space, they need to be kmapped separately for doing IO on the pages.  The
 * struct page (these bits with information) are always mapped into kernel
 * address space...
 *
 * PG_hwpoison indicates that a page got corrupted in hardware and contains
 * data with incorrect ECC bits that triggered a machine check. Accessing is
 * not safe since it may cause another machine check. Don't touch!
 */

/*
 * Don't use the *_dontuse flags.  Use the macros.  Otherwise you'll break
 * locked- and dirty-page accounting.
 *
 * The page flags field is split into two parts, the main flags area
 * which extends from the low bits upwards, and the fields area which
 * extends from the high bits downwards.
 *
 *  | FIELD | ... | FLAGS |
 *  N-1           ^       0
 *               (NR_PAGEFLAGS)
 *
 * The fields area is reserved for fields mapping zone, node (for NUMA) and
 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like
 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
 */
enum pageflags {
	PG_locked,		/* Page is locked. Don't touch. */
	PG_error,
	PG_referenced,
	PG_uptodate,
	PG_dirty,
	PG_lru,
	PG_active,
	PG_slab,
	PG_owner_priv_1,	/* Owner use. If pagecache, fs may use*/
	PG_arch_1,
	PG_reserved,
	PG_private,		/* If pagecache, has fs-private data */
	PG_private_2,		/* If pagecache, has fs aux data */
	PG_writeback,		/* Page is under writeback */
	PG_head,		/* A head page */
	PG_swapcache,		/* Swap page: swp_entry_t in private */
	PG_mappedtodisk,	/* Has blocks allocated on-disk */
	PG_reclaim,		/* To be reclaimed asap */
	PG_swapbacked,		/* Page is backed by RAM/swap */
	PG_unevictable,		/* Page is "unevictable"  */
#ifdef CONFIG_MMU
	PG_mlocked,		/* Page is vma mlocked */
#endif
#ifdef CONFIG_ARCH_USES_PG_UNCACHED
	PG_uncached,		/* Page has been mapped as uncached */
#endif
#ifdef CONFIG_MEMORY_FAILURE
	PG_hwpoison,		/* hardware poisoned page. Don't touch */
#endif
#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
	PG_young,
	PG_idle,
#endif
	__NR_PAGEFLAGS,

	/* Filesystems */
	PG_checked = PG_owner_priv_1,

	/* Two page bits are conscripted by FS-Cache to maintain local caching
	 * state.  These bits are set on pages belonging to the netfs's inodes
	 * when those inodes are being locally cached.
	 */
	PG_fscache = PG_private_2,	/* page backed by cache */

	/* XEN */
	/* Pinned in Xen as a read-only pagetable page. */
	PG_pinned = PG_owner_priv_1,
	/* Pinned as part of domain save (see xen_mm_pin_all()). */
	PG_savepinned = PG_dirty,
	/* Has a grant mapping of another (foreign) domain's page. */
	PG_foreign = PG_owner_priv_1,

	/* SLOB */
	PG_slob_free = PG_private,

	/* Compound pages. Stored in first tail page's flags */
	PG_double_map = PG_private_2,
};

#ifndef __GENERATING_BOUNDS_H

struct page;	/* forward declaration */

static inline struct page *compound_head(struct page *page)
{
	unsigned long head = READ_ONCE(page->compound_head);

	if (unlikely(head & 1))
		return (struct page *) (head - 1);
	return page;
}

static __always_inline int PageTail(struct page *page)
{
	return READ_ONCE(page->compound_head) & 1;
}

static __always_inline int PageCompound(struct page *page)
{
	return test_bit(PG_head, &page->flags) || PageTail(page);
}

/*
 * Page flags policies wrt compound pages
 *
 * PF_ANY:
 *     the page flag is relevant for small, head and tail pages.
 *
 * PF_HEAD:
 *     for compound page all operations related to the page flag applied to
 *     head page.
 *
 * PF_NO_TAIL:
 *     modifications of the page flag must be done on small or head pages,
 *     checks can be done on tail pages too.
 *
 * PF_NO_COMPOUND:
 *     the page flag is not relevant for compound pages.
 */
#define PF_ANY(page, enforce)	page
#define PF_HEAD(page, enforce)	compound_head(page)
#define PF_NO_TAIL(page, enforce) ({					\
		VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page);	\
		compound_head(page);})
#define PF_NO_COMPOUND(page, enforce) ({				\
		VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page);	\
		page;})

/*
 * Macros to create function definitions for page flags
 */
#define TESTPAGEFLAG(uname, lname, policy)				\
static __always_inline int Page##uname(struct page *page)		\
	{ return test_bit(PG_##lname, &policy(page, 0)->flags); }

#define SETPAGEFLAG(uname, lname, policy)				\
static __always_inline void SetPage##uname(struct page *page)		\
	{ set_bit(PG_##lname, &policy(page, 1)->flags); }

#define CLEARPAGEFLAG(uname, lname, policy)				\
static __always_inline void ClearPage##uname(struct page *page)		\
	{ clear_bit(PG_##lname, &policy(page, 1)->flags); }

#define __SETPAGEFLAG(uname, lname, policy)				\
static __always_inline void __SetPage##uname(struct page *page)		\
	{ __set_bit(PG_##lname, &policy(page, 1)->flags); }

#define __CLEARPAGEFLAG(uname, lname, policy)				\
static __always_inline void __ClearPage##uname(struct page *page)	\
	{ __clear_bit(PG_##lname, &policy(page, 1)->flags); }

#define TESTSETFLAG(uname, lname, policy)				\
static __always_inline int TestSetPage##uname(struct page *page)	\
	{ return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }

#define TESTCLEARFLAG(uname, lname, policy)				\
static __always_inline int TestClearPage##uname(struct page *page)	\
	{ return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }

#define PAGEFLAG(uname, lname, policy)					\
	TESTPAGEFLAG(uname, lname, policy)				\
	SETPAGEFLAG(uname, lname, policy)				\
	CLEARPAGEFLAG(uname, lname, policy)

#define __PAGEFLAG(uname, lname, policy)				\
	TESTPAGEFLAG(uname, lname, policy)				\
	__SETPAGEFLAG(uname, lname, policy)				\
	__CLEARPAGEFLAG(uname, lname, policy)

#define TESTSCFLAG(uname, lname, policy)				\
	TESTSETFLAG(uname, lname, policy)				\
	TESTCLEARFLAG(uname, lname, policy)

#define TESTPAGEFLAG_FALSE(uname)					\
static inline int Page##uname(const struct page *page) { return 0; }

#define SETPAGEFLAG_NOOP(uname)						\
static inline void SetPage##uname(struct page *page) {  }

#define CLEARPAGEFLAG_NOOP(uname)					\
static inline void ClearPage##uname(struct page *page) {  }

#define __CLEARPAGEFLAG_NOOP(uname)					\
static inline void __ClearPage##uname(struct page *page) {  }

#define TESTSETFLAG_FALSE(uname)					\
static inline int TestSetPage##uname(struct page *page) { return 0; }

#define TESTCLEARFLAG_FALSE(uname)					\
static inline int TestClearPage##uname(struct page *page) { return 0; }

#define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname)			\
	SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)

#define TESTSCFLAG_FALSE(uname)						\
	TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)

__PAGEFLAG(Locked, locked, PF_NO_TAIL)
PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND)
PAGEFLAG(Referenced, referenced, PF_HEAD)
	TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
	__SETPAGEFLAG(Referenced, referenced, PF_HEAD)
PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
	__CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
	TESTCLEARFLAG(Active, active, PF_HEAD)
__PAGEFLAG(Slab, slab, PF_NO_TAIL)
__PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
PAGEFLAG(Checked, checked, PF_NO_COMPOUND)	   /* Used by some filesystems */

/* Xen */
PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
	TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);

PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
	__CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
	__CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
	__SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)

/*
 * Private page markings that may be used by the filesystem that owns the page
 * for its own purposes.
 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
 */
PAGEFLAG(Private, private, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY)
	__CLEARPAGEFLAG(Private, private, PF_ANY)
PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
	TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)

/*
 * Only test-and-set exist for PG_writeback.  The unconditional operators are
 * risky: they bypass page accounting.
 */
TESTPAGEFLAG(Writeback, writeback, PF_NO_COMPOUND)
	TESTSCFLAG(Writeback, writeback, PF_NO_COMPOUND)
PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_COMPOUND)

/* PG_readahead is only used for reads; PG_reclaim is only for writes */
PAGEFLAG(Reclaim, reclaim, PF_NO_COMPOUND)
	TESTCLEARFLAG(Reclaim, reclaim, PF_NO_COMPOUND)
PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
	TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)

#ifdef CONFIG_HIGHMEM
/*
 * Must use a macro here due to header dependency issues. page_zone() is not
 * available at this point.
 */
#define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
#else
PAGEFLAG_FALSE(HighMem)
#endif

#ifdef CONFIG_SWAP
PAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND)
#else
PAGEFLAG_FALSE(SwapCache)
#endif

PAGEFLAG(Unevictable, unevictable, PF_HEAD)
	__CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
	TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)

#ifdef CONFIG_MMU
PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
	__CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
	TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
#else
PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
	TESTSCFLAG_FALSE(Mlocked)
#endif

#ifdef CONFIG_ARCH_USES_PG_UNCACHED
PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
#else
PAGEFLAG_FALSE(Uncached)
#endif

#ifdef CONFIG_MEMORY_FAILURE
PAGEFLAG(HWPoison, hwpoison, PF_ANY)
TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
#define __PG_HWPOISON (1UL << PG_hwpoison)
#else
PAGEFLAG_FALSE(HWPoison)
#define __PG_HWPOISON 0
#endif

#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
TESTPAGEFLAG(Young, young, PF_ANY)
SETPAGEFLAG(Young, young, PF_ANY)
TESTCLEARFLAG(Young, young, PF_ANY)
PAGEFLAG(Idle, idle, PF_ANY)
#endif

/*
 * On an anonymous page mapped into a user virtual memory area,
 * page->mapping points to its anon_vma, not to a struct address_space;
 * with the PAGE_MAPPING_ANON bit set to distinguish it.  See rmap.h.
 *
 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
 * the PAGE_MAPPING_KSM bit may be set along with the PAGE_MAPPING_ANON bit;
 * and then page->mapping points, not to an anon_vma, but to a private
 * structure which KSM associates with that merged page.  See ksm.h.
 *
 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is currently never used.
 *
 * Please note that, confusingly, "page_mapping" refers to the inode
 * address_space which maps the page from disk; whereas "page_mapped"
 * refers to user virtual address space into which the page is mapped.
 */
#define PAGE_MAPPING_ANON	1
#define PAGE_MAPPING_KSM	2
#define PAGE_MAPPING_FLAGS	(PAGE_MAPPING_ANON | PAGE_MAPPING_KSM)

static __always_inline int PageAnonHead(struct page *page)
{
	return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
}

static __always_inline int PageAnon(struct page *page)
{
	page = compound_head(page);
	return PageAnonHead(page);
}

#ifdef CONFIG_KSM
/*
 * A KSM page is one of those write-protected "shared pages" or "merged pages"
 * which KSM maps into multiple mms, wherever identical anonymous page content
 * is found in VM_MERGEABLE vmas.  It's a PageAnon page, pointing not to any
 * anon_vma, but to that page's node of the stable tree.
 */
static __always_inline int PageKsm(struct page *page)
{
	page = compound_head(page);
	return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
				(PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
}
#else
TESTPAGEFLAG_FALSE(Ksm)
#endif

u64 stable_page_flags(struct page *page);

static inline int PageUptodate(struct page *page)
{
	int ret;
	page = compound_head(page);
	ret = test_bit(PG_uptodate, &(page)->flags);
	/*
	 * Must ensure that the data we read out of the page is loaded
	 * _after_ we've loaded page->flags to check for PageUptodate.
	 * We can skip the barrier if the page is not uptodate, because
	 * we wouldn't be reading anything from it.
	 *
	 * See SetPageUptodate() for the other side of the story.
	 */
	if (ret)
		smp_rmb();

	return ret;
}

static __always_inline void __SetPageUptodate(struct page *page)
{
	VM_BUG_ON_PAGE(PageTail(page), page);
	smp_wmb();
	__set_bit(PG_uptodate, &page->flags);
}

static __always_inline void SetPageUptodate(struct page *page)
{
	VM_BUG_ON_PAGE(PageTail(page), page);
	/*
	 * Memory barrier must be issued before setting the PG_uptodate bit,
	 * so that all previous stores issued in order to bring the page
	 * uptodate are actually visible before PageUptodate becomes true.
	 */
	smp_wmb();
	set_bit(PG_uptodate, &page->flags);
}

CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)

int test_clear_page_writeback(struct page *page);
int __test_set_page_writeback(struct page *page, bool keep_write);

#define test_set_page_writeback(page)			\
	__test_set_page_writeback(page, false)
#define test_set_page_writeback_keepwrite(page)	\
	__test_set_page_writeback(page, true)

static inline void set_page_writeback(struct page *page)
{
	test_set_page_writeback(page);
}

static inline void set_page_writeback_keepwrite(struct page *page)
{
	test_set_page_writeback_keepwrite(page);
}

__PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)

static __always_inline void set_compound_head(struct page *page, struct page *head)
{
	WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
}

static __always_inline void clear_compound_head(struct page *page)
{
	WRITE_ONCE(page->compound_head, 0);
}

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static inline void ClearPageCompound(struct page *page)
{
	BUG_ON(!PageHead(page));
	ClearPageHead(page);
}
#endif

#define PG_head_mask ((1UL << PG_head))

#ifdef CONFIG_HUGETLB_PAGE
int PageHuge(struct page *page);
int PageHeadHuge(struct page *page);
bool page_huge_active(struct page *page);
#else
TESTPAGEFLAG_FALSE(Huge)
TESTPAGEFLAG_FALSE(HeadHuge)

static inline bool page_huge_active(struct page *page)
{
	return 0;
}
#endif


#ifdef CONFIG_TRANSPARENT_HUGEPAGE
/*
 * PageHuge() only returns true for hugetlbfs pages, but not for
 * normal or transparent huge pages.
 *
 * PageTransHuge() returns true for both transparent huge and
 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
 * called only in the core VM paths where hugetlbfs pages can't exist.
 */
static inline int PageTransHuge(struct page *page)
{
	VM_BUG_ON_PAGE(PageTail(page), page);
	return PageHead(page);
}

/*
 * PageTransCompound returns true for both transparent huge pages
 * and hugetlbfs pages, so it should only be called when it's known
 * that hugetlbfs pages aren't involved.
 */
static inline int PageTransCompound(struct page *page)
{
	return PageCompound(page);
}

/*
 * PageTransCompoundMap is the same as PageTransCompound, but it also
 * guarantees the primary MMU has the entire compound page mapped
 * through pmd_trans_huge, which in turn guarantees the secondary MMUs
 * can also map the entire compound page. This allows the secondary
 * MMUs to call get_user_pages() only once for each compound page and
 * to immediately map the entire compound page with a single secondary
 * MMU fault. If there will be a pmd split later, the secondary MMUs
 * will get an update through the MMU notifier invalidation through
 * split_huge_pmd().
 *
 * Unlike PageTransCompound, this is safe to be called only while
 * split_huge_pmd() cannot run from under us, like if protected by the
 * MMU notifier, otherwise it may result in page->_mapcount < 0 false
 * positives.
 */
static inline int PageTransCompoundMap(struct page *page)
{
	return PageTransCompound(page) && atomic_read(&page->_mapcount) < 0;
}

/*
 * PageTransTail returns true for both transparent huge pages
 * and hugetlbfs pages, so it should only be called when it's known
 * that hugetlbfs pages aren't involved.
 */
static inline int PageTransTail(struct page *page)
{
	return PageTail(page);
}

/*
 * PageDoubleMap indicates that the compound page is mapped with PTEs as well
 * as PMDs.
 *
 * This is required for optimization of rmap operations for THP: we can postpone
 * per small page mapcount accounting (and its overhead from atomic operations)
 * until the first PMD split.
 *
 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
 * by one. This reference will go away with last compound_mapcount.
 *
 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
 */
static inline int PageDoubleMap(struct page *page)
{
	return PageHead(page) && test_bit(PG_double_map, &page[1].flags);
}

static inline int TestSetPageDoubleMap(struct page *page)
{
	VM_BUG_ON_PAGE(!PageHead(page), page);
	return test_and_set_bit(PG_double_map, &page[1].flags);
}

static inline int TestClearPageDoubleMap(struct page *page)
{
	VM_BUG_ON_PAGE(!PageHead(page), page);
	return test_and_clear_bit(PG_double_map, &page[1].flags);
}

#else
TESTPAGEFLAG_FALSE(TransHuge)
TESTPAGEFLAG_FALSE(TransCompound)
TESTPAGEFLAG_FALSE(TransCompoundMap)
TESTPAGEFLAG_FALSE(TransTail)
TESTPAGEFLAG_FALSE(DoubleMap)
	TESTSETFLAG_FALSE(DoubleMap)
	TESTCLEARFLAG_FALSE(DoubleMap)
#endif

/*
 * PageBuddy() indicate that the page is free and in the buddy system
 * (see mm/page_alloc.c).
 *
 * PAGE_BUDDY_MAPCOUNT_VALUE must be <= -2 but better not too close to
 * -2 so that an underflow of the page_mapcount() won't be mistaken
 * for a genuine PAGE_BUDDY_MAPCOUNT_VALUE. -128 can be created very
 * efficiently by most CPU architectures.
 */
#define PAGE_BUDDY_MAPCOUNT_VALUE (-128)

static inline int PageBuddy(struct page *page)
{
	return atomic_read(&page->_mapcount) == PAGE_BUDDY_MAPCOUNT_VALUE;
}

static inline void __SetPageBuddy(struct page *page)
{
	VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
	atomic_set(&page->_mapcount, PAGE_BUDDY_MAPCOUNT_VALUE);
}

static inline void __ClearPageBuddy(struct page *page)
{
	VM_BUG_ON_PAGE(!PageBuddy(page), page);
	atomic_set(&page->_mapcount, -1);
}

extern bool is_free_buddy_page(struct page *page);

#define PAGE_BALLOON_MAPCOUNT_VALUE (-256)

static inline int PageBalloon(struct page *page)
{
	return atomic_read(&page->_mapcount) == PAGE_BALLOON_MAPCOUNT_VALUE;
}

static inline void __SetPageBalloon(struct page *page)
{
	VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
	atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE);
}

static inline void __ClearPageBalloon(struct page *page)
{
	VM_BUG_ON_PAGE(!PageBalloon(page), page);
	atomic_set(&page->_mapcount, -1);
}

/*
 * If network-based swap is enabled, sl*b must keep track of whether pages
 * were allocated from pfmemalloc reserves.
 */
static inline int PageSlabPfmemalloc(struct page *page)
{
	VM_BUG_ON_PAGE(!PageSlab(page), page);
	return PageActive(page);
}

static inline void SetPageSlabPfmemalloc(struct page *page)
{
	VM_BUG_ON_PAGE(!PageSlab(page), page);
	SetPageActive(page);
}

static inline void __ClearPageSlabPfmemalloc(struct page *page)
{
	VM_BUG_ON_PAGE(!PageSlab(page), page);
	__ClearPageActive(page);
}

static inline void ClearPageSlabPfmemalloc(struct page *page)
{
	VM_BUG_ON_PAGE(!PageSlab(page), page);
	ClearPageActive(page);
}

#ifdef CONFIG_MMU
#define __PG_MLOCKED		(1UL << PG_mlocked)
#else
#define __PG_MLOCKED		0
#endif

/*
 * Flags checked when a page is freed.  Pages being freed should not have
 * these flags set.  It they are, there is a problem.
 */
#define PAGE_FLAGS_CHECK_AT_FREE \
	(1UL << PG_lru	 | 1UL << PG_locked    | \
	 1UL << PG_private | 1UL << PG_private_2 | \
	 1UL << PG_writeback | 1UL << PG_reserved | \
	 1UL << PG_slab	 | 1UL << PG_swapcache | 1UL << PG_active | \
	 1UL << PG_unevictable | __PG_MLOCKED)

/*
 * Flags checked when a page is prepped for return by the page allocator.
 * Pages being prepped should not have these flags set.  It they are set,
 * there has been a kernel bug or struct page corruption.
 *
 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
 * alloc-free cycle to prevent from reusing the page.
 */
#define PAGE_FLAGS_CHECK_AT_PREP	\
	(((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)

#define PAGE_FLAGS_PRIVATE				\
	(1UL << PG_private | 1UL << PG_private_2)
/**
 * page_has_private - Determine if page has private stuff
 * @page: The page to be checked
 *
 * Determine if a page has private stuff, indicating that release routines
 * should be invoked upon it.
 */
static inline int page_has_private(struct page *page)
{
	return !!(page->flags & PAGE_FLAGS_PRIVATE);
}

#undef PF_ANY
#undef PF_HEAD
#undef PF_NO_TAIL
#undef PF_NO_COMPOUND
#endif /* !__GENERATING_BOUNDS_H */

#endif	/* PAGE_FLAGS_H */