summaryrefslogtreecommitdiffstats
path: root/include/linux/page-flags.h
blob: a88e64acebfea27f501dbdf39fad57ab81533579 (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
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
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
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
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
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
/* SPDX-License-Identifier: GPL-2.0 */
/*
 * 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. The "struct page" of such a page
 * should in general not be touched (e.g. set dirty) except by its owner.
 * Pages marked as PG_reserved include:
 * - Pages part of the kernel image (including vDSO) and similar (e.g. BIOS,
 *   initrd, HW tables)
 * - Pages reserved or allocated early during boot (before the page allocator
 *   was initialized). This includes (depending on the architecture) the
 *   initial vmemmap, initial page tables, crashkernel, elfcorehdr, and much
 *   much more. Once (if ever) freed, PG_reserved is cleared and they will
 *   be given to the page allocator.
 * - Pages falling into physical memory gaps - not IORESOURCE_SYSRAM. Trying
 *   to read/write these pages might end badly. Don't touch!
 * - The zero page(s)
 * - Pages not added to the page allocator when onlining a section because
 *   they were excluded via the online_page_callback() or because they are
 *   PG_hwpoison.
 * - Pages allocated in the context of kexec/kdump (loaded kernel image,
 *   control pages, vmcoreinfo)
 * - MMIO/DMA pages. Some architectures don't allow to ioremap pages that are
 *   not marked PG_reserved (as they might be in use by somebody else who does
 *   not respect the caching strategy).
 * - Pages part of an offline section (struct pages of offline sections should
 *   not be trusted as they will be initialized when first onlined).
 * - MCA pages on ia64
 * - Pages holding CPU notes for POWER Firmware Assisted Dump
 * - Device memory (e.g. PMEM, DAX, HMM)
 * Some PG_reserved pages will be excluded from the hibernation image.
 * PG_reserved does in general not hinder anybody from dumping or swapping
 * and is no longer required for remap_pfn_range(). ioremap might require it.
 * Consequently, PG_reserved for a page mapped into user space can indicate
 * the zero page, the vDSO, MMIO pages or device memory.
 *
 * 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_swapbacked is set when a page uses swap as a backing storage.  This are
 * usually PageAnon or shmem pages but please note that even anonymous pages
 * might lose their PG_swapbacked flag when they simply can be dropped (e.g. as
 * a result of MADV_FREE).
 *
 * 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_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 pageflags directly.  Use the PageFoo macros.
 *
 * 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_writeback,		/* Page is under writeback */
	PG_referenced,
	PG_uptodate,
	PG_dirty,
	PG_lru,
	PG_head,		/* Must be in bit 6 */
	PG_waiters,		/* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
	PG_active,
	PG_workingset,
	PG_error,
	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_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_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
	PG_young,
	PG_idle,
#endif
#ifdef CONFIG_ARCH_USES_PG_ARCH_X
	PG_arch_2,
	PG_arch_3,
#endif
	__NR_PAGEFLAGS,

	PG_readahead = PG_reclaim,

	/*
	 * Depending on the way an anonymous folio can be mapped into a page
	 * table (e.g., single PMD/PUD/CONT of the head page vs. PTE-mapped
	 * THP), PG_anon_exclusive may be set only for the head page or for
	 * tail pages of an anonymous folio. For now, we only expect it to be
	 * set on tail pages for PTE-mapped THP.
	 */
	PG_anon_exclusive = PG_mappedtodisk,

	/* Filesystems */
	PG_checked = PG_owner_priv_1,

	/* SwapBacked */
	PG_swapcache = PG_owner_priv_1,	/* Swap page: swp_entry_t in private */

	/* 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,
	/* Remapped by swiotlb-xen. */
	PG_xen_remapped = PG_owner_priv_1,

	/* non-lru isolated movable page */
	PG_isolated = PG_reclaim,

	/* Only valid for buddy pages. Used to track pages that are reported */
	PG_reported = PG_uptodate,

#ifdef CONFIG_MEMORY_HOTPLUG
	/* For self-hosted memmap pages */
	PG_vmemmap_self_hosted = PG_owner_priv_1,
#endif

	/*
	 * Flags only valid for compound pages.  Stored in first tail page's
	 * flags word.  Cannot use the first 8 flags or any flag marked as
	 * PF_ANY.
	 */

	/* At least one page in this folio has the hwpoison flag set */
	PG_has_hwpoisoned = PG_error,
	PG_hugetlb = PG_active,
	PG_large_rmappable = PG_workingset, /* anon or file-backed */
};

#define PAGEFLAGS_MASK		((1UL << NR_PAGEFLAGS) - 1)

#ifndef __GENERATING_BOUNDS_H

#ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
DECLARE_STATIC_KEY_FALSE(hugetlb_optimize_vmemmap_key);

/*
 * Return the real head page struct iff the @page is a fake head page, otherwise
 * return the @page itself. See Documentation/mm/vmemmap_dedup.rst.
 */
static __always_inline const struct page *page_fixed_fake_head(const struct page *page)
{
	if (!static_branch_unlikely(&hugetlb_optimize_vmemmap_key))
		return page;

	/*
	 * Only addresses aligned with PAGE_SIZE of struct page may be fake head
	 * struct page. The alignment check aims to avoid access the fields (
	 * e.g. compound_head) of the @page[1]. It can avoid touch a (possibly)
	 * cold cacheline in some cases.
	 */
	if (IS_ALIGNED((unsigned long)page, PAGE_SIZE) &&
	    test_bit(PG_head, &page->flags)) {
		/*
		 * We can safely access the field of the @page[1] with PG_head
		 * because the @page is a compound page composed with at least
		 * two contiguous pages.
		 */
		unsigned long head = READ_ONCE(page[1].compound_head);

		if (likely(head & 1))
			return (const struct page *)(head - 1);
	}
	return page;
}
#else
static inline const struct page *page_fixed_fake_head(const struct page *page)
{
	return page;
}
#endif

static __always_inline int page_is_fake_head(struct page *page)
{
	return page_fixed_fake_head(page) != page;
}

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

	if (unlikely(head & 1))
		return head - 1;
	return (unsigned long)page_fixed_fake_head(page);
}

#define compound_head(page)	((typeof(page))_compound_head(page))

/**
 * page_folio - Converts from page to folio.
 * @p: The page.
 *
 * Every page is part of a folio.  This function cannot be called on a
 * NULL pointer.
 *
 * Context: No reference, nor lock is required on @page.  If the caller
 * does not hold a reference, this call may race with a folio split, so
 * it should re-check the folio still contains this page after gaining
 * a reference on the folio.
 * Return: The folio which contains this page.
 */
#define page_folio(p)		(_Generic((p),				\
	const struct page *:	(const struct folio *)_compound_head(p), \
	struct page *:		(struct folio *)_compound_head(p)))

/**
 * folio_page - Return a page from a folio.
 * @folio: The folio.
 * @n: The page number to return.
 *
 * @n is relative to the start of the folio.  This function does not
 * check that the page number lies within @folio; the caller is presumed
 * to have a reference to the page.
 */
#define folio_page(folio, n)	nth_page(&(folio)->page, n)

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

static __always_inline int PageCompound(struct page *page)
{
	return test_bit(PG_head, &page->flags) ||
	       READ_ONCE(page->compound_head) & 1;
}

#define	PAGE_POISON_PATTERN	-1l
static inline int PagePoisoned(const struct page *page)
{
	return READ_ONCE(page->flags) == PAGE_POISON_PATTERN;
}

#ifdef CONFIG_DEBUG_VM
void page_init_poison(struct page *page, size_t size);
#else
static inline void page_init_poison(struct page *page, size_t size)
{
}
#endif

static unsigned long *folio_flags(struct folio *folio, unsigned n)
{
	struct page *page = &folio->page;

	VM_BUG_ON_PGFLAGS(PageTail(page), page);
	VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags), page);
	return &page[n].flags;
}

/*
 * Page flags policies wrt compound pages
 *
 * PF_POISONED_CHECK
 *     check if this struct page poisoned/uninitialized
 *
 * 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_ONLY_HEAD:
 *     for compound page, callers only ever operate on the 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.
 *
 * PF_SECOND:
 *     the page flag is stored in the first tail page.
 */
#define PF_POISONED_CHECK(page) ({					\
		VM_BUG_ON_PGFLAGS(PagePoisoned(page), page);		\
		page; })
#define PF_ANY(page, enforce)	PF_POISONED_CHECK(page)
#define PF_HEAD(page, enforce)	PF_POISONED_CHECK(compound_head(page))
#define PF_ONLY_HEAD(page, enforce) ({					\
		VM_BUG_ON_PGFLAGS(PageTail(page), page);		\
		PF_POISONED_CHECK(page); })
#define PF_NO_TAIL(page, enforce) ({					\
		VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page);	\
		PF_POISONED_CHECK(compound_head(page)); })
#define PF_NO_COMPOUND(page, enforce) ({				\
		VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page);	\
		PF_POISONED_CHECK(page); })
#define PF_SECOND(page, enforce) ({					\
		VM_BUG_ON_PGFLAGS(!PageHead(page), page);		\
		PF_POISONED_CHECK(&page[1]); })

/* Which page is the flag stored in */
#define FOLIO_PF_ANY		0
#define FOLIO_PF_HEAD		0
#define FOLIO_PF_ONLY_HEAD	0
#define FOLIO_PF_NO_TAIL	0
#define FOLIO_PF_NO_COMPOUND	0
#define FOLIO_PF_SECOND		1

/*
 * Macros to create function definitions for page flags
 */
#define TESTPAGEFLAG(uname, lname, policy)				\
static __always_inline bool folio_test_##lname(struct folio *folio)	\
{ return test_bit(PG_##lname, folio_flags(folio, FOLIO_##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 folio_set_##lname(struct folio *folio)				\
{ set_bit(PG_##lname, folio_flags(folio, FOLIO_##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 folio_clear_##lname(struct folio *folio)				\
{ clear_bit(PG_##lname, folio_flags(folio, FOLIO_##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 __folio_set_##lname(struct folio *folio)				\
{ __set_bit(PG_##lname, folio_flags(folio, FOLIO_##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 __folio_clear_##lname(struct folio *folio)				\
{ __clear_bit(PG_##lname, folio_flags(folio, FOLIO_##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							\
bool folio_test_set_##lname(struct folio *folio)			\
{ return test_and_set_bit(PG_##lname, folio_flags(folio, FOLIO_##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							\
bool folio_test_clear_##lname(struct folio *folio)			\
{ return test_and_clear_bit(PG_##lname, folio_flags(folio, FOLIO_##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, lname)				\
static inline bool folio_test_##lname(const struct folio *folio) { return false; } \
static inline int Page##uname(const struct page *page) { return 0; }

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

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

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

#define TESTSETFLAG_FALSE(uname, lname)					\
static inline bool folio_test_set_##lname(struct folio *folio)		\
{ return 0; }								\
static inline int TestSetPage##uname(struct page *page) { return 0; }

#define TESTCLEARFLAG_FALSE(uname, lname)				\
static inline bool folio_test_clear_##lname(struct folio *folio)	\
{ return 0; }								\
static inline int TestClearPage##uname(struct page *page) { return 0; }

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

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

__PAGEFLAG(Locked, locked, PF_NO_TAIL)
PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
PAGEFLAG(Error, error, PF_NO_TAIL) TESTCLEARFLAG(Error, error, PF_NO_TAIL)
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)
	TESTCLEARFLAG(LRU, lru, PF_HEAD)
PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
	TESTCLEARFLAG(Active, active, PF_HEAD)
PAGEFLAG(Workingset, workingset, PF_HEAD)
	TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
__PAGEFLAG(Slab, slab, 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(XenRemapped, xen_remapped, PF_NO_COMPOUND)
	TESTCLEARFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)

PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
	__CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
	__SETPAGEFLAG(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 release_folio() and co to be invoked
 */
PAGEFLAG(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_TAIL)
	TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)
PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)

/* PG_readahead is only used for reads; PG_reclaim is only for writes */
PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
	TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
PAGEFLAG(Readahead, readahead, PF_NO_COMPOUND)
	TESTCLEARFLAG(Readahead, readahead, 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))
#define folio_test_highmem(__f)	is_highmem_idx(folio_zonenum(__f))
#else
PAGEFLAG_FALSE(HighMem, highmem)
#endif

#ifdef CONFIG_SWAP
static __always_inline bool folio_test_swapcache(struct folio *folio)
{
	return folio_test_swapbacked(folio) &&
			test_bit(PG_swapcache, folio_flags(folio, 0));
}

static __always_inline bool PageSwapCache(struct page *page)
{
	return folio_test_swapcache(page_folio(page));
}

SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
#else
PAGEFLAG_FALSE(SwapCache, 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, mlocked) __CLEARPAGEFLAG_NOOP(Mlocked, mlocked)
	TESTSCFLAG_FALSE(Mlocked, mlocked)
#endif

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

#ifdef CONFIG_MEMORY_FAILURE
PAGEFLAG(HWPoison, hwpoison, PF_ANY)
TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
#define __PG_HWPOISON (1UL << PG_hwpoison)
#define MAGIC_HWPOISON	0x48575053U	/* HWPS */
extern void SetPageHWPoisonTakenOff(struct page *page);
extern void ClearPageHWPoisonTakenOff(struct page *page);
extern bool take_page_off_buddy(struct page *page);
extern bool put_page_back_buddy(struct page *page);
#else
PAGEFLAG_FALSE(HWPoison, hwpoison)
#define __PG_HWPOISON 0
#endif

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

/*
 * PageReported() is used to track reported free pages within the Buddy
 * allocator. We can use the non-atomic version of the test and set
 * operations as both should be shielded with the zone lock to prevent
 * any possible races on the setting or clearing of the bit.
 */
__PAGEFLAG(Reported, reported, PF_NO_COMPOUND)

#ifdef CONFIG_MEMORY_HOTPLUG
PAGEFLAG(VmemmapSelfHosted, vmemmap_self_hosted, PF_ANY)
#else
PAGEFLAG_FALSE(VmemmapSelfHosted, vmemmap_self_hosted)
#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_MOVABLE 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 used for non-lru movable
 * page and then page->mapping points to a struct movable_operations.
 *
 * 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.
 *
 * For slab pages, since slab reuses the bits in struct page to store its
 * internal states, the page->mapping does not exist as such, nor do these
 * flags below.  So in order to avoid testing non-existent bits, please
 * make sure that PageSlab(page) actually evaluates to false before calling
 * the following functions (e.g., PageAnon).  See mm/slab.h.
 */
#define PAGE_MAPPING_ANON	0x1
#define PAGE_MAPPING_MOVABLE	0x2
#define PAGE_MAPPING_KSM	(PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
#define PAGE_MAPPING_FLAGS	(PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)

/*
 * Different with flags above, this flag is used only for fsdax mode.  It
 * indicates that this page->mapping is now under reflink case.
 */
#define PAGE_MAPPING_DAX_SHARED	((void *)0x1)

static __always_inline bool folio_mapping_flags(struct folio *folio)
{
	return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) != 0;
}

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

static __always_inline bool folio_test_anon(struct folio *folio)
{
	return ((unsigned long)folio->mapping & PAGE_MAPPING_ANON) != 0;
}

static __always_inline bool PageAnon(struct page *page)
{
	return folio_test_anon(page_folio(page));
}

static __always_inline bool __folio_test_movable(const struct folio *folio)
{
	return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
			PAGE_MAPPING_MOVABLE;
}

static __always_inline int __PageMovable(struct page *page)
{
	return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
				PAGE_MAPPING_MOVABLE;
}

#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 bool folio_test_ksm(struct folio *folio)
{
	return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
				PAGE_MAPPING_KSM;
}

static __always_inline bool PageKsm(struct page *page)
{
	return folio_test_ksm(page_folio(page));
}
#else
TESTPAGEFLAG_FALSE(Ksm, ksm)
#endif

u64 stable_page_flags(struct page *page);

/**
 * folio_xor_flags_has_waiters - Change some folio flags.
 * @folio: The folio.
 * @mask: Bits set in this word will be changed.
 *
 * This must only be used for flags which are changed with the folio
 * lock held.  For example, it is unsafe to use for PG_dirty as that
 * can be set without the folio lock held.  It can also only be used
 * on flags which are in the range 0-6 as some of the implementations
 * only affect those bits.
 *
 * Return: Whether there are tasks waiting on the folio.
 */
static inline bool folio_xor_flags_has_waiters(struct folio *folio,
		unsigned long mask)
{
	return xor_unlock_is_negative_byte(mask, folio_flags(folio, 0));
}

/**
 * folio_test_uptodate - Is this folio up to date?
 * @folio: The folio.
 *
 * The uptodate flag is set on a folio when every byte in the folio is
 * at least as new as the corresponding bytes on storage.  Anonymous
 * and CoW folios are always uptodate.  If the folio is not uptodate,
 * some of the bytes in it may be; see the is_partially_uptodate()
 * address_space operation.
 */
static inline bool folio_test_uptodate(struct folio *folio)
{
	bool ret = test_bit(PG_uptodate, folio_flags(folio, 0));
	/*
	 * Must ensure that the data we read out of the folio is loaded
	 * _after_ we've loaded folio->flags to check the uptodate bit.
	 * We can skip the barrier if the folio is not uptodate, because
	 * we wouldn't be reading anything from it.
	 *
	 * See folio_mark_uptodate() for the other side of the story.
	 */
	if (ret)
		smp_rmb();

	return ret;
}

static inline int PageUptodate(struct page *page)
{
	return folio_test_uptodate(page_folio(page));
}

static __always_inline void __folio_mark_uptodate(struct folio *folio)
{
	smp_wmb();
	__set_bit(PG_uptodate, folio_flags(folio, 0));
}

static __always_inline void folio_mark_uptodate(struct folio *folio)
{
	/*
	 * Memory barrier must be issued before setting the PG_uptodate bit,
	 * so that all previous stores issued in order to bring the folio
	 * uptodate are actually visible before folio_test_uptodate becomes true.
	 */
	smp_wmb();
	set_bit(PG_uptodate, folio_flags(folio, 0));
}

static __always_inline void __SetPageUptodate(struct page *page)
{
	__folio_mark_uptodate((struct folio *)page);
}

static __always_inline void SetPageUptodate(struct page *page)
{
	folio_mark_uptodate((struct folio *)page);
}

CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)

bool __folio_start_writeback(struct folio *folio, bool keep_write);
bool set_page_writeback(struct page *page);

#define folio_start_writeback(folio)			\
	__folio_start_writeback(folio, false)
#define folio_start_writeback_keepwrite(folio)	\
	__folio_start_writeback(folio, true)

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

static __always_inline bool folio_test_head(struct folio *folio)
{
	return test_bit(PG_head, folio_flags(folio, FOLIO_PF_ANY));
}

static __always_inline int PageHead(struct page *page)
{
	PF_POISONED_CHECK(page);
	return test_bit(PG_head, &page->flags) && !page_is_fake_head(page);
}

__SETPAGEFLAG(Head, head, PF_ANY)
__CLEARPAGEFLAG(Head, head, PF_ANY)
CLEARPAGEFLAG(Head, head, PF_ANY)

/**
 * folio_test_large() - Does this folio contain more than one page?
 * @folio: The folio to test.
 *
 * Return: True if the folio is larger than one page.
 */
static inline bool folio_test_large(struct folio *folio)
{
	return folio_test_head(folio);
}

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);
}
PAGEFLAG(LargeRmappable, large_rmappable, PF_SECOND)
#else
TESTPAGEFLAG_FALSE(LargeRmappable, large_rmappable)
#endif

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

#ifdef CONFIG_HUGETLB_PAGE
int PageHuge(struct page *page);
SETPAGEFLAG(HugeTLB, hugetlb, PF_SECOND)
CLEARPAGEFLAG(HugeTLB, hugetlb, PF_SECOND)

/**
 * folio_test_hugetlb - Determine if the folio belongs to hugetlbfs
 * @folio: The folio to test.
 *
 * Context: Any context.  Caller should have a reference on the folio to
 * prevent it from being turned into a tail page.
 * Return: True for hugetlbfs folios, false for anon folios or folios
 * belonging to other filesystems.
 */
static inline bool folio_test_hugetlb(struct folio *folio)
{
	return folio_test_large(folio) &&
		test_bit(PG_hugetlb, folio_flags(folio, 1));
}
#else
TESTPAGEFLAG_FALSE(Huge, hugetlb)
#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);
}

/*
 * 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);
}
#else
TESTPAGEFLAG_FALSE(TransHuge, transhuge)
TESTPAGEFLAG_FALSE(TransCompound, transcompound)
TESTPAGEFLAG_FALSE(TransCompoundMap, transcompoundmap)
TESTPAGEFLAG_FALSE(TransTail, transtail)
#endif

#if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
/*
 * PageHasHWPoisoned indicates that at least one subpage is hwpoisoned in the
 * compound page.
 *
 * This flag is set by hwpoison handler.  Cleared by THP split or free page.
 */
PAGEFLAG(HasHWPoisoned, has_hwpoisoned, PF_SECOND)
	TESTSCFLAG(HasHWPoisoned, has_hwpoisoned, PF_SECOND)
#else
PAGEFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
	TESTSCFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
#endif

/*
 * Check if a page is currently marked HWPoisoned. Note that this check is
 * best effort only and inherently racy: there is no way to synchronize with
 * failing hardware.
 */
static inline bool is_page_hwpoison(struct page *page)
{
	if (PageHWPoison(page))
		return true;
	return PageHuge(page) && PageHWPoison(compound_head(page));
}

/*
 * For pages that are never mapped to userspace (and aren't PageSlab),
 * page_type may be used.  Because it is initialised to -1, we invert the
 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
 * __ClearPageFoo *sets* the bit used for PageFoo.  We reserve a few high and
 * low bits so that an underflow or overflow of page_mapcount() won't be
 * mistaken for a page type value.
 */

#define PAGE_TYPE_BASE	0xf0000000
/* Reserve		0x0000007f to catch underflows of page_mapcount */
#define PAGE_MAPCOUNT_RESERVE	-128
#define PG_buddy	0x00000080
#define PG_offline	0x00000100
#define PG_table	0x00000200
#define PG_guard	0x00000400

#define PageType(page, flag)						\
	((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
#define folio_test_type(folio, flag)					\
	((folio->page.page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)

static inline int page_type_has_type(unsigned int page_type)
{
	return (int)page_type < PAGE_MAPCOUNT_RESERVE;
}

static inline int page_has_type(struct page *page)
{
	return page_type_has_type(page->page_type);
}

#define PAGE_TYPE_OPS(uname, lname, fname)				\
static __always_inline int Page##uname(const struct page *page)		\
{									\
	return PageType(page, PG_##lname);				\
}									\
static __always_inline int folio_test_##fname(const struct folio *folio)\
{									\
	return folio_test_type(folio, PG_##lname);			\
}									\
static __always_inline void __SetPage##uname(struct page *page)		\
{									\
	VM_BUG_ON_PAGE(!PageType(page, 0), page);			\
	page->page_type &= ~PG_##lname;					\
}									\
static __always_inline void __folio_set_##fname(struct folio *folio)	\
{									\
	VM_BUG_ON_FOLIO(!folio_test_type(folio, 0), folio);		\
	folio->page.page_type &= ~PG_##lname;				\
}									\
static __always_inline void __ClearPage##uname(struct page *page)	\
{									\
	VM_BUG_ON_PAGE(!Page##uname(page), page);			\
	page->page_type |= PG_##lname;					\
}									\
static __always_inline void __folio_clear_##fname(struct folio *folio)	\
{									\
	VM_BUG_ON_FOLIO(!folio_test_##fname(folio), folio);		\
	folio->page.page_type |= PG_##lname;				\
}									\

/*
 * PageBuddy() indicates that the page is free and in the buddy system
 * (see mm/page_alloc.c).
 */
PAGE_TYPE_OPS(Buddy, buddy, buddy)

/*
 * PageOffline() indicates that the page is logically offline although the
 * containing section is online. (e.g. inflated in a balloon driver or
 * not onlined when onlining the section).
 * The content of these pages is effectively stale. Such pages should not
 * be touched (read/write/dump/save) except by their owner.
 *
 * If a driver wants to allow to offline unmovable PageOffline() pages without
 * putting them back to the buddy, it can do so via the memory notifier by
 * decrementing the reference count in MEM_GOING_OFFLINE and incrementing the
 * reference count in MEM_CANCEL_OFFLINE. When offlining, the PageOffline()
 * pages (now with a reference count of zero) are treated like free pages,
 * allowing the containing memory block to get offlined. A driver that
 * relies on this feature is aware that re-onlining the memory block will
 * require to re-set the pages PageOffline() and not giving them to the
 * buddy via online_page_callback_t.
 *
 * There are drivers that mark a page PageOffline() and expect there won't be
 * any further access to page content. PFN walkers that read content of random
 * pages should check PageOffline() and synchronize with such drivers using
 * page_offline_freeze()/page_offline_thaw().
 */
PAGE_TYPE_OPS(Offline, offline, offline)

extern void page_offline_freeze(void);
extern void page_offline_thaw(void);
extern void page_offline_begin(void);
extern void page_offline_end(void);

/*
 * Marks pages in use as page tables.
 */
PAGE_TYPE_OPS(Table, table, pgtable)

/*
 * Marks guardpages used with debug_pagealloc.
 */
PAGE_TYPE_OPS(Guard, guard, guard)

extern bool is_free_buddy_page(struct page *page);

PAGEFLAG(Isolated, isolated, PF_ANY);

static __always_inline int PageAnonExclusive(struct page *page)
{
	VM_BUG_ON_PGFLAGS(!PageAnon(page), page);
	VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
	return test_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
}

static __always_inline void SetPageAnonExclusive(struct page *page)
{
	VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
	VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
	set_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
}

static __always_inline void ClearPageAnonExclusive(struct page *page)
{
	VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
	VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
	clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
}

static __always_inline void __ClearPageAnonExclusive(struct page *page)
{
	VM_BUG_ON_PGFLAGS(!PageAnon(page), page);
	VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
	__clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
}

#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.  If 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_active 	|	\
	 1UL << PG_unevictable	| __PG_MLOCKED | LRU_GEN_MASK)

/*
 * Flags checked when a page is prepped for return by the page allocator.
 * Pages being prepped should not have these flags set.  If 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	\
	((PAGEFLAGS_MASK & ~__PG_HWPOISON) | LRU_GEN_MASK | LRU_REFS_MASK)

/*
 * Flags stored in the second page of a compound page.  They may overlap
 * the CHECK_AT_FREE flags above, so need to be cleared.
 */
#define PAGE_FLAGS_SECOND						\
	(0xffUL /* order */		| 1UL << PG_has_hwpoisoned |	\
	 1UL << PG_hugetlb		| 1UL << PG_large_rmappable)

#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);
}

static inline bool folio_has_private(struct folio *folio)
{
	return page_has_private(&folio->page);
}

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

#endif	/* PAGE_FLAGS_H */