1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Macros for manipulating and testing page->flags
4 */
5
6#ifndef PAGE_FLAGS_H
7#define PAGE_FLAGS_H
8
9#include <linux/types.h>
10#include <linux/bug.h>
11#include <linux/mmdebug.h>
12#ifndef __GENERATING_BOUNDS_H
13#include <linux/mm_types.h>
14#include <generated/bounds.h>
15#endif /* !__GENERATING_BOUNDS_H */
16
17/*
18 * Various page->flags bits:
19 *
20 * PG_reserved is set for special pages. The "struct page" of such a page
21 * should in general not be touched (e.g. set dirty) except by its owner.
22 * Pages marked as PG_reserved include:
23 * - Pages part of the kernel image (including vDSO) and similar (e.g. BIOS,
24 * initrd, HW tables)
25 * - Pages reserved or allocated early during boot (before the page allocator
26 * was initialized). This includes (depending on the architecture) the
27 * initial vmemmap, initial page tables, crashkernel, elfcorehdr, and much
28 * much more. Once (if ever) freed, PG_reserved is cleared and they will
29 * be given to the page allocator.
30 * - Pages falling into physical memory gaps - not IORESOURCE_SYSRAM. Trying
31 * to read/write these pages might end badly. Don't touch!
32 * - The zero page(s)
33 * - Pages not added to the page allocator when onlining a section because
34 * they were excluded via the online_page_callback() or because they are
35 * PG_hwpoison.
36 * - Pages allocated in the context of kexec/kdump (loaded kernel image,
37 * control pages, vmcoreinfo)
38 * - MMIO/DMA pages. Some architectures don't allow to ioremap pages that are
39 * not marked PG_reserved (as they might be in use by somebody else who does
40 * not respect the caching strategy).
41 * - Pages part of an offline section (struct pages of offline sections should
42 * not be trusted as they will be initialized when first onlined).
43 * - MCA pages on ia64
44 * - Pages holding CPU notes for POWER Firmware Assisted Dump
45 * - Device memory (e.g. PMEM, DAX, HMM)
46 * Some PG_reserved pages will be excluded from the hibernation image.
47 * PG_reserved does in general not hinder anybody from dumping or swapping
48 * and is no longer required for remap_pfn_range(). ioremap might require it.
49 * Consequently, PG_reserved for a page mapped into user space can indicate
50 * the zero page, the vDSO, MMIO pages or device memory.
51 *
52 * The PG_private bitflag is set on pagecache pages if they contain filesystem
53 * specific data (which is normally at page->private). It can be used by
54 * private allocations for its own usage.
55 *
56 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O
57 * and cleared when writeback _starts_ or when read _completes_. PG_writeback
58 * is set before writeback starts and cleared when it finishes.
59 *
60 * PG_locked also pins a page in pagecache, and blocks truncation of the file
61 * while it is held.
62 *
63 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
64 * to become unlocked.
65 *
66 * PG_swapbacked is set when a page uses swap as a backing storage. This are
67 * usually PageAnon or shmem pages but please note that even anonymous pages
68 * might lose their PG_swapbacked flag when they simply can be dropped (e.g. as
69 * a result of MADV_FREE).
70 *
71 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
72 * file-backed pagecache (see mm/vmscan.c).
73 *
74 * PG_error is set to indicate that an I/O error occurred on this page.
75 *
76 * PG_arch_1 is an architecture specific page state bit. The generic code
77 * guarantees that this bit is cleared for a page when it first is entered into
78 * the page cache.
79 *
80 * PG_hwpoison indicates that a page got corrupted in hardware and contains
81 * data with incorrect ECC bits that triggered a machine check. Accessing is
82 * not safe since it may cause another machine check. Don't touch!
83 */
84
85/*
86 * Don't use the pageflags directly. Use the PageFoo macros.
87 *
88 * The page flags field is split into two parts, the main flags area
89 * which extends from the low bits upwards, and the fields area which
90 * extends from the high bits downwards.
91 *
92 * | FIELD | ... | FLAGS |
93 * N-1 ^ 0
94 * (NR_PAGEFLAGS)
95 *
96 * The fields area is reserved for fields mapping zone, node (for NUMA) and
97 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like
98 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
99 */
100enum pageflags {
101 PG_locked, /* Page is locked. Don't touch. */
102 PG_referenced,
103 PG_uptodate,
104 PG_dirty,
105 PG_lru,
106 PG_active,
107 PG_workingset,
108 PG_waiters, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
109 PG_error,
110 PG_slab,
111 PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
112 PG_arch_1,
113 PG_reserved,
114 PG_private, /* If pagecache, has fs-private data */
115 PG_private_2, /* If pagecache, has fs aux data */
116 PG_writeback, /* Page is under writeback */
117 PG_head, /* A head page */
118 PG_mappedtodisk, /* Has blocks allocated on-disk */
119 PG_reclaim, /* To be reclaimed asap */
120 PG_swapbacked, /* Page is backed by RAM/swap */
121 PG_unevictable, /* Page is "unevictable" */
122#ifdef CONFIG_MMU
123 PG_mlocked, /* Page is vma mlocked */
124#endif
125#ifdef CONFIG_ARCH_USES_PG_UNCACHED
126 PG_uncached, /* Page has been mapped as uncached */
127#endif
128#ifdef CONFIG_MEMORY_FAILURE
129 PG_hwpoison, /* hardware poisoned page. Don't touch */
130#endif
131#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
132 PG_young,
133 PG_idle,
134#endif
135#ifdef CONFIG_64BIT
136 PG_arch_2,
137#endif
138#ifdef CONFIG_KASAN_HW_TAGS
139 PG_skip_kasan_poison,
140#endif
141 __NR_PAGEFLAGS,
142
143 PG_readahead = PG_reclaim,
144
145 /*
146 * Depending on the way an anonymous folio can be mapped into a page
147 * table (e.g., single PMD/PUD/CONT of the head page vs. PTE-mapped
148 * THP), PG_anon_exclusive may be set only for the head page or for
149 * tail pages of an anonymous folio. For now, we only expect it to be
150 * set on tail pages for PTE-mapped THP.
151 */
152 PG_anon_exclusive = PG_mappedtodisk,
153
154 /* Filesystems */
155 PG_checked = PG_owner_priv_1,
156
157 /* SwapBacked */
158 PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */
159
160 /* Two page bits are conscripted by FS-Cache to maintain local caching
161 * state. These bits are set on pages belonging to the netfs's inodes
162 * when those inodes are being locally cached.
163 */
164 PG_fscache = PG_private_2, /* page backed by cache */
165
166 /* XEN */
167 /* Pinned in Xen as a read-only pagetable page. */
168 PG_pinned = PG_owner_priv_1,
169 /* Pinned as part of domain save (see xen_mm_pin_all()). */
170 PG_savepinned = PG_dirty,
171 /* Has a grant mapping of another (foreign) domain's page. */
172 PG_foreign = PG_owner_priv_1,
173 /* Remapped by swiotlb-xen. */
174 PG_xen_remapped = PG_owner_priv_1,
175
176 /* SLOB */
177 PG_slob_free = PG_private,
178
179 /* Compound pages. Stored in first tail page's flags */
180 PG_double_map = PG_workingset,
181
182#ifdef CONFIG_MEMORY_FAILURE
183 /*
184 * Compound pages. Stored in first tail page's flags.
185 * Indicates that at least one subpage is hwpoisoned in the
186 * THP.
187 */
188 PG_has_hwpoisoned = PG_error,
189#endif
190
191 /* non-lru isolated movable page */
192 PG_isolated = PG_reclaim,
193
194 /* Only valid for buddy pages. Used to track pages that are reported */
195 PG_reported = PG_uptodate,
196
197#ifdef CONFIG_MEMORY_HOTPLUG
198 /* For self-hosted memmap pages */
199 PG_vmemmap_self_hosted = PG_owner_priv_1,
200#endif
201};
202
203#define PAGEFLAGS_MASK ((1UL << NR_PAGEFLAGS) - 1)
204
205#ifndef __GENERATING_BOUNDS_H
206
207#ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
208DECLARE_STATIC_KEY_FALSE(hugetlb_optimize_vmemmap_key);
209
210/*
211 * Return the real head page struct iff the @page is a fake head page, otherwise
212 * return the @page itself. See Documentation/mm/vmemmap_dedup.rst.
213 */
214static __always_inline const struct page *page_fixed_fake_head(const struct page *page)
215{
216 if (!static_branch_unlikely(&hugetlb_optimize_vmemmap_key))
217 return page;
218
219 /*
220 * Only addresses aligned with PAGE_SIZE of struct page may be fake head
221 * struct page. The alignment check aims to avoid access the fields (
222 * e.g. compound_head) of the @page[1]. It can avoid touch a (possibly)
223 * cold cacheline in some cases.
224 */
225 if (IS_ALIGNED((unsigned long)page, PAGE_SIZE) &&
226 test_bit(PG_head, &page->flags)) {
227 /*
228 * We can safely access the field of the @page[1] with PG_head
229 * because the @page is a compound page composed with at least
230 * two contiguous pages.
231 */
232 unsigned long head = READ_ONCE(page[1].compound_head);
233
234 if (likely(head & 1))
235 return (const struct page *)(head - 1);
236 }
237 return page;
238}
239#else
240static inline const struct page *page_fixed_fake_head(const struct page *page)
241{
242 return page;
243}
244#endif
245
246static __always_inline int page_is_fake_head(struct page *page)
247{
248 return page_fixed_fake_head(page) != page;
249}
250
251static inline unsigned long _compound_head(const struct page *page)
252{
253 unsigned long head = READ_ONCE(page->compound_head);
254
255 if (unlikely(head & 1))
256 return head - 1;
257 return (unsigned long)page_fixed_fake_head(page);
258}
259
260#define compound_head(page) ((typeof(page))_compound_head(page))
261
262/**
263 * page_folio - Converts from page to folio.
264 * @p: The page.
265 *
266 * Every page is part of a folio. This function cannot be called on a
267 * NULL pointer.
268 *
269 * Context: No reference, nor lock is required on @page. If the caller
270 * does not hold a reference, this call may race with a folio split, so
271 * it should re-check the folio still contains this page after gaining
272 * a reference on the folio.
273 * Return: The folio which contains this page.
274 */
275#define page_folio(p) (_Generic((p), \
276 const struct page *: (const struct folio *)_compound_head(p), \
277 struct page *: (struct folio *)_compound_head(p)))
278
279/**
280 * folio_page - Return a page from a folio.
281 * @folio: The folio.
282 * @n: The page number to return.
283 *
284 * @n is relative to the start of the folio. This function does not
285 * check that the page number lies within @folio; the caller is presumed
286 * to have a reference to the page.
287 */
288#define folio_page(folio, n) nth_page(&(folio)->page, n)
289
290static __always_inline int PageTail(struct page *page)
291{
292 return READ_ONCE(page->compound_head) & 1 || page_is_fake_head(page);
293}
294
295static __always_inline int PageCompound(struct page *page)
296{
297 return test_bit(PG_head, &page->flags) ||
298 READ_ONCE(page->compound_head) & 1;
299}
300
301#define PAGE_POISON_PATTERN -1l
302static inline int PagePoisoned(const struct page *page)
303{
304 return READ_ONCE(page->flags) == PAGE_POISON_PATTERN;
305}
306
307#ifdef CONFIG_DEBUG_VM
308void page_init_poison(struct page *page, size_t size);
309#else
310static inline void page_init_poison(struct page *page, size_t size)
311{
312}
313#endif
314
315static unsigned long *folio_flags(struct folio *folio, unsigned n)
316{
317 struct page *page = &folio->page;
318
319 VM_BUG_ON_PGFLAGS(PageTail(page), page);
320 VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags), page);
321 return &page[n].flags;
322}
323
324/*
325 * Page flags policies wrt compound pages
326 *
327 * PF_POISONED_CHECK
328 * check if this struct page poisoned/uninitialized
329 *
330 * PF_ANY:
331 * the page flag is relevant for small, head and tail pages.
332 *
333 * PF_HEAD:
334 * for compound page all operations related to the page flag applied to
335 * head page.
336 *
337 * PF_ONLY_HEAD:
338 * for compound page, callers only ever operate on the head page.
339 *
340 * PF_NO_TAIL:
341 * modifications of the page flag must be done on small or head pages,
342 * checks can be done on tail pages too.
343 *
344 * PF_NO_COMPOUND:
345 * the page flag is not relevant for compound pages.
346 *
347 * PF_SECOND:
348 * the page flag is stored in the first tail page.
349 */
350#define PF_POISONED_CHECK(page) ({ \
351 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \
352 page; })
353#define PF_ANY(page, enforce) PF_POISONED_CHECK(page)
354#define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page))
355#define PF_ONLY_HEAD(page, enforce) ({ \
356 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
357 PF_POISONED_CHECK(page); })
358#define PF_NO_TAIL(page, enforce) ({ \
359 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
360 PF_POISONED_CHECK(compound_head(page)); })
361#define PF_NO_COMPOUND(page, enforce) ({ \
362 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
363 PF_POISONED_CHECK(page); })
364#define PF_SECOND(page, enforce) ({ \
365 VM_BUG_ON_PGFLAGS(!PageHead(page), page); \
366 PF_POISONED_CHECK(&page[1]); })
367
368/* Which page is the flag stored in */
369#define FOLIO_PF_ANY 0
370#define FOLIO_PF_HEAD 0
371#define FOLIO_PF_ONLY_HEAD 0
372#define FOLIO_PF_NO_TAIL 0
373#define FOLIO_PF_NO_COMPOUND 0
374#define FOLIO_PF_SECOND 1
375
376/*
377 * Macros to create function definitions for page flags
378 */
379#define TESTPAGEFLAG(uname, lname, policy) \
380static __always_inline bool folio_test_##lname(struct folio *folio) \
381{ return test_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
382static __always_inline int Page##uname(struct page *page) \
383{ return test_bit(PG_##lname, &policy(page, 0)->flags); }
384
385#define SETPAGEFLAG(uname, lname, policy) \
386static __always_inline \
387void folio_set_##lname(struct folio *folio) \
388{ set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
389static __always_inline void SetPage##uname(struct page *page) \
390{ set_bit(PG_##lname, &policy(page, 1)->flags); }
391
392#define CLEARPAGEFLAG(uname, lname, policy) \
393static __always_inline \
394void folio_clear_##lname(struct folio *folio) \
395{ clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
396static __always_inline void ClearPage##uname(struct page *page) \
397{ clear_bit(PG_##lname, &policy(page, 1)->flags); }
398
399#define __SETPAGEFLAG(uname, lname, policy) \
400static __always_inline \
401void __folio_set_##lname(struct folio *folio) \
402{ __set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
403static __always_inline void __SetPage##uname(struct page *page) \
404{ __set_bit(PG_##lname, &policy(page, 1)->flags); }
405
406#define __CLEARPAGEFLAG(uname, lname, policy) \
407static __always_inline \
408void __folio_clear_##lname(struct folio *folio) \
409{ __clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
410static __always_inline void __ClearPage##uname(struct page *page) \
411{ __clear_bit(PG_##lname, &policy(page, 1)->flags); }
412
413#define TESTSETFLAG(uname, lname, policy) \
414static __always_inline \
415bool folio_test_set_##lname(struct folio *folio) \
416{ return test_and_set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
417static __always_inline int TestSetPage##uname(struct page *page) \
418{ return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
419
420#define TESTCLEARFLAG(uname, lname, policy) \
421static __always_inline \
422bool folio_test_clear_##lname(struct folio *folio) \
423{ return test_and_clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
424static __always_inline int TestClearPage##uname(struct page *page) \
425{ return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
426
427#define PAGEFLAG(uname, lname, policy) \
428 TESTPAGEFLAG(uname, lname, policy) \
429 SETPAGEFLAG(uname, lname, policy) \
430 CLEARPAGEFLAG(uname, lname, policy)
431
432#define __PAGEFLAG(uname, lname, policy) \
433 TESTPAGEFLAG(uname, lname, policy) \
434 __SETPAGEFLAG(uname, lname, policy) \
435 __CLEARPAGEFLAG(uname, lname, policy)
436
437#define TESTSCFLAG(uname, lname, policy) \
438 TESTSETFLAG(uname, lname, policy) \
439 TESTCLEARFLAG(uname, lname, policy)
440
441#define TESTPAGEFLAG_FALSE(uname, lname) \
442static inline bool folio_test_##lname(const struct folio *folio) { return false; } \
443static inline int Page##uname(const struct page *page) { return 0; }
444
445#define SETPAGEFLAG_NOOP(uname, lname) \
446static inline void folio_set_##lname(struct folio *folio) { } \
447static inline void SetPage##uname(struct page *page) { }
448
449#define CLEARPAGEFLAG_NOOP(uname, lname) \
450static inline void folio_clear_##lname(struct folio *folio) { } \
451static inline void ClearPage##uname(struct page *page) { }
452
453#define __CLEARPAGEFLAG_NOOP(uname, lname) \
454static inline void __folio_clear_##lname(struct folio *folio) { } \
455static inline void __ClearPage##uname(struct page *page) { }
456
457#define TESTSETFLAG_FALSE(uname, lname) \
458static inline bool folio_test_set_##lname(struct folio *folio) \
459{ return 0; } \
460static inline int TestSetPage##uname(struct page *page) { return 0; }
461
462#define TESTCLEARFLAG_FALSE(uname, lname) \
463static inline bool folio_test_clear_##lname(struct folio *folio) \
464{ return 0; } \
465static inline int TestClearPage##uname(struct page *page) { return 0; }
466
467#define PAGEFLAG_FALSE(uname, lname) TESTPAGEFLAG_FALSE(uname, lname) \
468 SETPAGEFLAG_NOOP(uname, lname) CLEARPAGEFLAG_NOOP(uname, lname)
469
470#define TESTSCFLAG_FALSE(uname, lname) \
471 TESTSETFLAG_FALSE(uname, lname) TESTCLEARFLAG_FALSE(uname, lname)
472
473__PAGEFLAG(Locked, locked, PF_NO_TAIL)
474PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
475PAGEFLAG(Error, error, PF_NO_TAIL) TESTCLEARFLAG(Error, error, PF_NO_TAIL)
476PAGEFLAG(Referenced, referenced, PF_HEAD)
477 TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
478 __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
479PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
480 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
481PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
482 TESTCLEARFLAG(LRU, lru, PF_HEAD)
483PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
484 TESTCLEARFLAG(Active, active, PF_HEAD)
485PAGEFLAG(Workingset, workingset, PF_HEAD)
486 TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
487__PAGEFLAG(Slab, slab, PF_NO_TAIL)
488__PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
489PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
490
491/* Xen */
492PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
493 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
494PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
495PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
496PAGEFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
497 TESTCLEARFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
498
499PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
500 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
501 __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
502PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
503 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
504 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
505
506/*
507 * Private page markings that may be used by the filesystem that owns the page
508 * for its own purposes.
509 * - PG_private and PG_private_2 cause release_folio() and co to be invoked
510 */
511PAGEFLAG(Private, private, PF_ANY)
512PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
513PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
514 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
515
516/*
517 * Only test-and-set exist for PG_writeback. The unconditional operators are
518 * risky: they bypass page accounting.
519 */
520TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL)
521 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)
522PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
523
524/* PG_readahead is only used for reads; PG_reclaim is only for writes */
525PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
526 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
527PAGEFLAG(Readahead, readahead, PF_NO_COMPOUND)
528 TESTCLEARFLAG(Readahead, readahead, PF_NO_COMPOUND)
529
530#ifdef CONFIG_HIGHMEM
531/*
532 * Must use a macro here due to header dependency issues. page_zone() is not
533 * available at this point.
534 */
535#define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
536#else
537PAGEFLAG_FALSE(HighMem, highmem)
538#endif
539
540#ifdef CONFIG_SWAP
541static __always_inline bool folio_test_swapcache(struct folio *folio)
542{
543 return folio_test_swapbacked(folio) &&
544 test_bit(PG_swapcache, folio_flags(folio, 0));
545}
546
547static __always_inline bool PageSwapCache(struct page *page)
548{
549 return folio_test_swapcache(page_folio(page));
550}
551
552SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
553CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
554#else
555PAGEFLAG_FALSE(SwapCache, swapcache)
556#endif
557
558PAGEFLAG(Unevictable, unevictable, PF_HEAD)
559 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
560 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
561
562#ifdef CONFIG_MMU
563PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
564 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
565 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
566#else
567PAGEFLAG_FALSE(Mlocked, mlocked) __CLEARPAGEFLAG_NOOP(Mlocked, mlocked)
568 TESTSCFLAG_FALSE(Mlocked, mlocked)
569#endif
570
571#ifdef CONFIG_ARCH_USES_PG_UNCACHED
572PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
573#else
574PAGEFLAG_FALSE(Uncached, uncached)
575#endif
576
577#ifdef CONFIG_MEMORY_FAILURE
578PAGEFLAG(HWPoison, hwpoison, PF_ANY)
579TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
580#define __PG_HWPOISON (1UL << PG_hwpoison)
581#define MAGIC_HWPOISON 0x48575053U /* HWPS */
582extern void SetPageHWPoisonTakenOff(struct page *page);
583extern void ClearPageHWPoisonTakenOff(struct page *page);
584extern bool take_page_off_buddy(struct page *page);
585extern bool put_page_back_buddy(struct page *page);
586#else
587PAGEFLAG_FALSE(HWPoison, hwpoison)
588#define __PG_HWPOISON 0
589#endif
590
591#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
592TESTPAGEFLAG(Young, young, PF_ANY)
593SETPAGEFLAG(Young, young, PF_ANY)
594TESTCLEARFLAG(Young, young, PF_ANY)
595PAGEFLAG(Idle, idle, PF_ANY)
596#endif
597
598#ifdef CONFIG_KASAN_HW_TAGS
599PAGEFLAG(SkipKASanPoison, skip_kasan_poison, PF_HEAD)
600#else
601PAGEFLAG_FALSE(SkipKASanPoison, skip_kasan_poison)
602#endif
603
604/*
605 * PageReported() is used to track reported free pages within the Buddy
606 * allocator. We can use the non-atomic version of the test and set
607 * operations as both should be shielded with the zone lock to prevent
608 * any possible races on the setting or clearing of the bit.
609 */
610__PAGEFLAG(Reported, reported, PF_NO_COMPOUND)
611
612#ifdef CONFIG_MEMORY_HOTPLUG
613PAGEFLAG(VmemmapSelfHosted, vmemmap_self_hosted, PF_ANY)
614#else
615PAGEFLAG_FALSE(VmemmapSelfHosted, vmemmap_self_hosted)
616#endif
617
618/*
619 * On an anonymous page mapped into a user virtual memory area,
620 * page->mapping points to its anon_vma, not to a struct address_space;
621 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
622 *
623 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
624 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
625 * bit; and then page->mapping points, not to an anon_vma, but to a private
626 * structure which KSM associates with that merged page. See ksm.h.
627 *
628 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
629 * page and then page->mapping points to a struct movable_operations.
630 *
631 * Please note that, confusingly, "page_mapping" refers to the inode
632 * address_space which maps the page from disk; whereas "page_mapped"
633 * refers to user virtual address space into which the page is mapped.
634 */
635#define PAGE_MAPPING_ANON 0x1
636#define PAGE_MAPPING_MOVABLE 0x2
637#define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
638#define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
639
640/*
641 * Different with flags above, this flag is used only for fsdax mode. It
642 * indicates that this page->mapping is now under reflink case.
643 */
644#define PAGE_MAPPING_DAX_COW 0x1
645
646static __always_inline bool folio_mapping_flags(struct folio *folio)
647{
648 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) != 0;
649}
650
651static __always_inline int PageMappingFlags(struct page *page)
652{
653 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
654}
655
656static __always_inline bool folio_test_anon(struct folio *folio)
657{
658 return ((unsigned long)folio->mapping & PAGE_MAPPING_ANON) != 0;
659}
660
661static __always_inline bool PageAnon(struct page *page)
662{
663 return folio_test_anon(page_folio(page));
664}
665
666static __always_inline bool __folio_test_movable(const struct folio *folio)
667{
668 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
669 PAGE_MAPPING_MOVABLE;
670}
671
672static __always_inline int __PageMovable(struct page *page)
673{
674 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
675 PAGE_MAPPING_MOVABLE;
676}
677
678#ifdef CONFIG_KSM
679/*
680 * A KSM page is one of those write-protected "shared pages" or "merged pages"
681 * which KSM maps into multiple mms, wherever identical anonymous page content
682 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
683 * anon_vma, but to that page's node of the stable tree.
684 */
685static __always_inline bool folio_test_ksm(struct folio *folio)
686{
687 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
688 PAGE_MAPPING_KSM;
689}
690
691static __always_inline bool PageKsm(struct page *page)
692{
693 return folio_test_ksm(page_folio(page));
694}
695#else
696TESTPAGEFLAG_FALSE(Ksm, ksm)
697#endif
698
699u64 stable_page_flags(struct page *page);
700
701/**
702 * folio_test_uptodate - Is this folio up to date?
703 * @folio: The folio.
704 *
705 * The uptodate flag is set on a folio when every byte in the folio is
706 * at least as new as the corresponding bytes on storage. Anonymous
707 * and CoW folios are always uptodate. If the folio is not uptodate,
708 * some of the bytes in it may be; see the is_partially_uptodate()
709 * address_space operation.
710 */
711static inline bool folio_test_uptodate(struct folio *folio)
712{
713 bool ret = test_bit(PG_uptodate, folio_flags(folio, 0));
714 /*
715 * Must ensure that the data we read out of the folio is loaded
716 * _after_ we've loaded folio->flags to check the uptodate bit.
717 * We can skip the barrier if the folio is not uptodate, because
718 * we wouldn't be reading anything from it.
719 *
720 * See folio_mark_uptodate() for the other side of the story.
721 */
722 if (ret)
723 smp_rmb();
724
725 return ret;
726}
727
728static inline int PageUptodate(struct page *page)
729{
730 return folio_test_uptodate(page_folio(page));
731}
732
733static __always_inline void __folio_mark_uptodate(struct folio *folio)
734{
735 smp_wmb();
736 __set_bit(PG_uptodate, folio_flags(folio, 0));
737}
738
739static __always_inline void folio_mark_uptodate(struct folio *folio)
740{
741 /*
742 * Memory barrier must be issued before setting the PG_uptodate bit,
743 * so that all previous stores issued in order to bring the folio
744 * uptodate are actually visible before folio_test_uptodate becomes true.
745 */
746 smp_wmb();
747 set_bit(PG_uptodate, folio_flags(folio, 0));
748}
749
750static __always_inline void __SetPageUptodate(struct page *page)
751{
752 __folio_mark_uptodate((struct folio *)page);
753}
754
755static __always_inline void SetPageUptodate(struct page *page)
756{
757 folio_mark_uptodate((struct folio *)page);
758}
759
760CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
761
762bool __folio_start_writeback(struct folio *folio, bool keep_write);
763bool set_page_writeback(struct page *page);
764
765#define folio_start_writeback(folio) \
766 __folio_start_writeback(folio, false)
767#define folio_start_writeback_keepwrite(folio) \
768 __folio_start_writeback(folio, true)
769
770static inline void set_page_writeback_keepwrite(struct page *page)
771{
772 folio_start_writeback_keepwrite(page_folio(page));
773}
774
775static inline bool test_set_page_writeback(struct page *page)
776{
777 return set_page_writeback(page);
778}
779
780static __always_inline bool folio_test_head(struct folio *folio)
781{
782 return test_bit(PG_head, folio_flags(folio, FOLIO_PF_ANY));
783}
784
785static __always_inline int PageHead(struct page *page)
786{
787 PF_POISONED_CHECK(page);
788 return test_bit(PG_head, &page->flags) && !page_is_fake_head(page);
789}
790
791__SETPAGEFLAG(Head, head, PF_ANY)
792__CLEARPAGEFLAG(Head, head, PF_ANY)
793CLEARPAGEFLAG(Head, head, PF_ANY)
794
795/**
796 * folio_test_large() - Does this folio contain more than one page?
797 * @folio: The folio to test.
798 *
799 * Return: True if the folio is larger than one page.
800 */
801static inline bool folio_test_large(struct folio *folio)
802{
803 return folio_test_head(folio);
804}
805
806static __always_inline void set_compound_head(struct page *page, struct page *head)
807{
808 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
809}
810
811static __always_inline void clear_compound_head(struct page *page)
812{
813 WRITE_ONCE(page->compound_head, 0);
814}
815
816#ifdef CONFIG_TRANSPARENT_HUGEPAGE
817static inline void ClearPageCompound(struct page *page)
818{
819 BUG_ON(!PageHead(page));
820 ClearPageHead(page);
821}
822#endif
823
824#define PG_head_mask ((1UL << PG_head))
825
826#ifdef CONFIG_HUGETLB_PAGE
827int PageHuge(struct page *page);
828int PageHeadHuge(struct page *page);
829static inline bool folio_test_hugetlb(struct folio *folio)
830{
831 return PageHeadHuge(&folio->page);
832}
833#else
834TESTPAGEFLAG_FALSE(Huge, hugetlb)
835TESTPAGEFLAG_FALSE(HeadHuge, headhuge)
836#endif
837
838#ifdef CONFIG_TRANSPARENT_HUGEPAGE
839/*
840 * PageHuge() only returns true for hugetlbfs pages, but not for
841 * normal or transparent huge pages.
842 *
843 * PageTransHuge() returns true for both transparent huge and
844 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
845 * called only in the core VM paths where hugetlbfs pages can't exist.
846 */
847static inline int PageTransHuge(struct page *page)
848{
849 VM_BUG_ON_PAGE(PageTail(page), page);
850 return PageHead(page);
851}
852
853static inline bool folio_test_transhuge(struct folio *folio)
854{
855 return folio_test_head(folio);
856}
857
858/*
859 * PageTransCompound returns true for both transparent huge pages
860 * and hugetlbfs pages, so it should only be called when it's known
861 * that hugetlbfs pages aren't involved.
862 */
863static inline int PageTransCompound(struct page *page)
864{
865 return PageCompound(page);
866}
867
868/*
869 * PageTransTail returns true for both transparent huge pages
870 * and hugetlbfs pages, so it should only be called when it's known
871 * that hugetlbfs pages aren't involved.
872 */
873static inline int PageTransTail(struct page *page)
874{
875 return PageTail(page);
876}
877
878/*
879 * PageDoubleMap indicates that the compound page is mapped with PTEs as well
880 * as PMDs.
881 *
882 * This is required for optimization of rmap operations for THP: we can postpone
883 * per small page mapcount accounting (and its overhead from atomic operations)
884 * until the first PMD split.
885 *
886 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
887 * by one. This reference will go away with last compound_mapcount.
888 *
889 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
890 */
891PAGEFLAG(DoubleMap, double_map, PF_SECOND)
892 TESTSCFLAG(DoubleMap, double_map, PF_SECOND)
893#else
894TESTPAGEFLAG_FALSE(TransHuge, transhuge)
895TESTPAGEFLAG_FALSE(TransCompound, transcompound)
896TESTPAGEFLAG_FALSE(TransCompoundMap, transcompoundmap)
897TESTPAGEFLAG_FALSE(TransTail, transtail)
898PAGEFLAG_FALSE(DoubleMap, double_map)
899 TESTSCFLAG_FALSE(DoubleMap, double_map)
900#endif
901
902#if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
903/*
904 * PageHasHWPoisoned indicates that at least one subpage is hwpoisoned in the
905 * compound page.
906 *
907 * This flag is set by hwpoison handler. Cleared by THP split or free page.
908 */
909PAGEFLAG(HasHWPoisoned, has_hwpoisoned, PF_SECOND)
910 TESTSCFLAG(HasHWPoisoned, has_hwpoisoned, PF_SECOND)
911#else
912PAGEFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
913 TESTSCFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
914#endif
915
916/*
917 * Check if a page is currently marked HWPoisoned. Note that this check is
918 * best effort only and inherently racy: there is no way to synchronize with
919 * failing hardware.
920 */
921static inline bool is_page_hwpoison(struct page *page)
922{
923 if (PageHWPoison(page))
924 return true;
925 return PageHuge(page) && PageHWPoison(compound_head(page));
926}
927
928/*
929 * For pages that are never mapped to userspace (and aren't PageSlab),
930 * page_type may be used. Because it is initialised to -1, we invert the
931 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
932 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
933 * low bits so that an underflow or overflow of page_mapcount() won't be
934 * mistaken for a page type value.
935 */
936
937#define PAGE_TYPE_BASE 0xf0000000
938/* Reserve 0x0000007f to catch underflows of page_mapcount */
939#define PAGE_MAPCOUNT_RESERVE -128
940#define PG_buddy 0x00000080
941#define PG_offline 0x00000100
942#define PG_table 0x00000200
943#define PG_guard 0x00000400
944
945#define PageType(page, flag) \
946 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
947
948static inline int page_has_type(struct page *page)
949{
950 return (int)page->page_type < PAGE_MAPCOUNT_RESERVE;
951}
952
953#define PAGE_TYPE_OPS(uname, lname) \
954static __always_inline int Page##uname(struct page *page) \
955{ \
956 return PageType(page, PG_##lname); \
957} \
958static __always_inline void __SetPage##uname(struct page *page) \
959{ \
960 VM_BUG_ON_PAGE(!PageType(page, 0), page); \
961 page->page_type &= ~PG_##lname; \
962} \
963static __always_inline void __ClearPage##uname(struct page *page) \
964{ \
965 VM_BUG_ON_PAGE(!Page##uname(page), page); \
966 page->page_type |= PG_##lname; \
967}
968
969/*
970 * PageBuddy() indicates that the page is free and in the buddy system
971 * (see mm/page_alloc.c).
972 */
973PAGE_TYPE_OPS(Buddy, buddy)
974
975/*
976 * PageOffline() indicates that the page is logically offline although the
977 * containing section is online. (e.g. inflated in a balloon driver or
978 * not onlined when onlining the section).
979 * The content of these pages is effectively stale. Such pages should not
980 * be touched (read/write/dump/save) except by their owner.
981 *
982 * If a driver wants to allow to offline unmovable PageOffline() pages without
983 * putting them back to the buddy, it can do so via the memory notifier by
984 * decrementing the reference count in MEM_GOING_OFFLINE and incrementing the
985 * reference count in MEM_CANCEL_OFFLINE. When offlining, the PageOffline()
986 * pages (now with a reference count of zero) are treated like free pages,
987 * allowing the containing memory block to get offlined. A driver that
988 * relies on this feature is aware that re-onlining the memory block will
989 * require to re-set the pages PageOffline() and not giving them to the
990 * buddy via online_page_callback_t.
991 *
992 * There are drivers that mark a page PageOffline() and expect there won't be
993 * any further access to page content. PFN walkers that read content of random
994 * pages should check PageOffline() and synchronize with such drivers using
995 * page_offline_freeze()/page_offline_thaw().
996 */
997PAGE_TYPE_OPS(Offline, offline)
998
999extern void page_offline_freeze(void);
1000extern void page_offline_thaw(void);
1001extern void page_offline_begin(void);
1002extern void page_offline_end(void);
1003
1004/*
1005 * Marks pages in use as page tables.
1006 */
1007PAGE_TYPE_OPS(Table, table)
1008
1009/*
1010 * Marks guardpages used with debug_pagealloc.
1011 */
1012PAGE_TYPE_OPS(Guard, guard)
1013
1014extern bool is_free_buddy_page(struct page *page);
1015
1016PAGEFLAG(Isolated, isolated, PF_ANY);
1017
1018static __always_inline int PageAnonExclusive(struct page *page)
1019{
1020 VM_BUG_ON_PGFLAGS(!PageAnon(page), page);
1021 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1022 return test_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1023}
1024
1025static __always_inline void SetPageAnonExclusive(struct page *page)
1026{
1027 VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
1028 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1029 set_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1030}
1031
1032static __always_inline void ClearPageAnonExclusive(struct page *page)
1033{
1034 VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
1035 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1036 clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1037}
1038
1039static __always_inline void __ClearPageAnonExclusive(struct page *page)
1040{
1041 VM_BUG_ON_PGFLAGS(!PageAnon(page), page);
1042 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1043 __clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1044}
1045
1046#ifdef CONFIG_MMU
1047#define __PG_MLOCKED (1UL << PG_mlocked)
1048#else
1049#define __PG_MLOCKED 0
1050#endif
1051
1052/*
1053 * Flags checked when a page is freed. Pages being freed should not have
1054 * these flags set. If they are, there is a problem.
1055 */
1056#define PAGE_FLAGS_CHECK_AT_FREE \
1057 (1UL << PG_lru | 1UL << PG_locked | \
1058 1UL << PG_private | 1UL << PG_private_2 | \
1059 1UL << PG_writeback | 1UL << PG_reserved | \
1060 1UL << PG_slab | 1UL << PG_active | \
1061 1UL << PG_unevictable | __PG_MLOCKED)
1062
1063/*
1064 * Flags checked when a page is prepped for return by the page allocator.
1065 * Pages being prepped should not have these flags set. If they are set,
1066 * there has been a kernel bug or struct page corruption.
1067 *
1068 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
1069 * alloc-free cycle to prevent from reusing the page.
1070 */
1071#define PAGE_FLAGS_CHECK_AT_PREP \
1072 (PAGEFLAGS_MASK & ~__PG_HWPOISON)
1073
1074#define PAGE_FLAGS_PRIVATE \
1075 (1UL << PG_private | 1UL << PG_private_2)
1076/**
1077 * page_has_private - Determine if page has private stuff
1078 * @page: The page to be checked
1079 *
1080 * Determine if a page has private stuff, indicating that release routines
1081 * should be invoked upon it.
1082 */
1083static inline int page_has_private(struct page *page)
1084{
1085 return !!(page->flags & PAGE_FLAGS_PRIVATE);
1086}
1087
1088static inline bool folio_has_private(struct folio *folio)
1089{
1090 return page_has_private(&folio->page);
1091}
1092
1093#undef PF_ANY
1094#undef PF_HEAD
1095#undef PF_ONLY_HEAD
1096#undef PF_NO_TAIL
1097#undef PF_NO_COMPOUND
1098#undef PF_SECOND
1099#endif /* !__GENERATING_BOUNDS_H */
1100
1101#endif /* PAGE_FLAGS_H */
1102

source code of linux/include/linux/page-flags.h