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_writeback, /* Page is under writeback */
103 PG_referenced,
104 PG_uptodate,
105 PG_dirty,
106 PG_lru,
107 PG_head, /* Must be in bit 6 */
108 PG_waiters, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
109 PG_active,
110 PG_workingset,
111 PG_error,
112 PG_slab,
113 PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
114 PG_arch_1,
115 PG_reserved,
116 PG_private, /* If pagecache, has fs-private data */
117 PG_private_2, /* If pagecache, has fs aux data */
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_ARCH_USES_PG_ARCH_X
136 PG_arch_2,
137 PG_arch_3,
138#endif
139 __NR_PAGEFLAGS,
140
141 PG_readahead = PG_reclaim,
142
143 /*
144 * Depending on the way an anonymous folio can be mapped into a page
145 * table (e.g., single PMD/PUD/CONT of the head page vs. PTE-mapped
146 * THP), PG_anon_exclusive may be set only for the head page or for
147 * tail pages of an anonymous folio. For now, we only expect it to be
148 * set on tail pages for PTE-mapped THP.
149 */
150 PG_anon_exclusive = PG_mappedtodisk,
151
152 /* Filesystems */
153 PG_checked = PG_owner_priv_1,
154
155 /* SwapBacked */
156 PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */
157
158 /* Two page bits are conscripted by FS-Cache to maintain local caching
159 * state. These bits are set on pages belonging to the netfs's inodes
160 * when those inodes are being locally cached.
161 */
162 PG_fscache = PG_private_2, /* page backed by cache */
163
164 /* XEN */
165 /* Pinned in Xen as a read-only pagetable page. */
166 PG_pinned = PG_owner_priv_1,
167 /* Pinned as part of domain save (see xen_mm_pin_all()). */
168 PG_savepinned = PG_dirty,
169 /* Has a grant mapping of another (foreign) domain's page. */
170 PG_foreign = PG_owner_priv_1,
171 /* Remapped by swiotlb-xen. */
172 PG_xen_remapped = PG_owner_priv_1,
173
174 /* non-lru isolated movable page */
175 PG_isolated = PG_reclaim,
176
177 /* Only valid for buddy pages. Used to track pages that are reported */
178 PG_reported = PG_uptodate,
179
180#ifdef CONFIG_MEMORY_HOTPLUG
181 /* For self-hosted memmap pages */
182 PG_vmemmap_self_hosted = PG_owner_priv_1,
183#endif
184
185 /*
186 * Flags only valid for compound pages. Stored in first tail page's
187 * flags word. Cannot use the first 8 flags or any flag marked as
188 * PF_ANY.
189 */
190
191 /* At least one page in this folio has the hwpoison flag set */
192 PG_has_hwpoisoned = PG_error,
193 PG_hugetlb = PG_active,
194 PG_large_rmappable = PG_workingset, /* anon or file-backed */
195};
196
197#define PAGEFLAGS_MASK ((1UL << NR_PAGEFLAGS) - 1)
198
199#ifndef __GENERATING_BOUNDS_H
200
201#ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
202DECLARE_STATIC_KEY_FALSE(hugetlb_optimize_vmemmap_key);
203
204/*
205 * Return the real head page struct iff the @page is a fake head page, otherwise
206 * return the @page itself. See Documentation/mm/vmemmap_dedup.rst.
207 */
208static __always_inline const struct page *page_fixed_fake_head(const struct page *page)
209{
210 if (!static_branch_unlikely(&hugetlb_optimize_vmemmap_key))
211 return page;
212
213 /*
214 * Only addresses aligned with PAGE_SIZE of struct page may be fake head
215 * struct page. The alignment check aims to avoid access the fields (
216 * e.g. compound_head) of the @page[1]. It can avoid touch a (possibly)
217 * cold cacheline in some cases.
218 */
219 if (IS_ALIGNED((unsigned long)page, PAGE_SIZE) &&
220 test_bit(PG_head, &page->flags)) {
221 /*
222 * We can safely access the field of the @page[1] with PG_head
223 * because the @page is a compound page composed with at least
224 * two contiguous pages.
225 */
226 unsigned long head = READ_ONCE(page[1].compound_head);
227
228 if (likely(head & 1))
229 return (const struct page *)(head - 1);
230 }
231 return page;
232}
233#else
234static inline const struct page *page_fixed_fake_head(const struct page *page)
235{
236 return page;
237}
238#endif
239
240static __always_inline int page_is_fake_head(struct page *page)
241{
242 return page_fixed_fake_head(page) != page;
243}
244
245static inline unsigned long _compound_head(const struct page *page)
246{
247 unsigned long head = READ_ONCE(page->compound_head);
248
249 if (unlikely(head & 1))
250 return head - 1;
251 return (unsigned long)page_fixed_fake_head(page);
252}
253
254#define compound_head(page) ((typeof(page))_compound_head(page))
255
256/**
257 * page_folio - Converts from page to folio.
258 * @p: The page.
259 *
260 * Every page is part of a folio. This function cannot be called on a
261 * NULL pointer.
262 *
263 * Context: No reference, nor lock is required on @page. If the caller
264 * does not hold a reference, this call may race with a folio split, so
265 * it should re-check the folio still contains this page after gaining
266 * a reference on the folio.
267 * Return: The folio which contains this page.
268 */
269#define page_folio(p) (_Generic((p), \
270 const struct page *: (const struct folio *)_compound_head(p), \
271 struct page *: (struct folio *)_compound_head(p)))
272
273/**
274 * folio_page - Return a page from a folio.
275 * @folio: The folio.
276 * @n: The page number to return.
277 *
278 * @n is relative to the start of the folio. This function does not
279 * check that the page number lies within @folio; the caller is presumed
280 * to have a reference to the page.
281 */
282#define folio_page(folio, n) nth_page(&(folio)->page, n)
283
284static __always_inline int PageTail(struct page *page)
285{
286 return READ_ONCE(page->compound_head) & 1 || page_is_fake_head(page);
287}
288
289static __always_inline int PageCompound(struct page *page)
290{
291 return test_bit(PG_head, &page->flags) ||
292 READ_ONCE(page->compound_head) & 1;
293}
294
295#define PAGE_POISON_PATTERN -1l
296static inline int PagePoisoned(const struct page *page)
297{
298 return READ_ONCE(page->flags) == PAGE_POISON_PATTERN;
299}
300
301#ifdef CONFIG_DEBUG_VM
302void page_init_poison(struct page *page, size_t size);
303#else
304static inline void page_init_poison(struct page *page, size_t size)
305{
306}
307#endif
308
309static unsigned long *folio_flags(struct folio *folio, unsigned n)
310{
311 struct page *page = &folio->page;
312
313 VM_BUG_ON_PGFLAGS(PageTail(page), page);
314 VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags), page);
315 return &page[n].flags;
316}
317
318/*
319 * Page flags policies wrt compound pages
320 *
321 * PF_POISONED_CHECK
322 * check if this struct page poisoned/uninitialized
323 *
324 * PF_ANY:
325 * the page flag is relevant for small, head and tail pages.
326 *
327 * PF_HEAD:
328 * for compound page all operations related to the page flag applied to
329 * head page.
330 *
331 * PF_ONLY_HEAD:
332 * for compound page, callers only ever operate on the head page.
333 *
334 * PF_NO_TAIL:
335 * modifications of the page flag must be done on small or head pages,
336 * checks can be done on tail pages too.
337 *
338 * PF_NO_COMPOUND:
339 * the page flag is not relevant for compound pages.
340 *
341 * PF_SECOND:
342 * the page flag is stored in the first tail page.
343 */
344#define PF_POISONED_CHECK(page) ({ \
345 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \
346 page; })
347#define PF_ANY(page, enforce) PF_POISONED_CHECK(page)
348#define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page))
349#define PF_ONLY_HEAD(page, enforce) ({ \
350 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
351 PF_POISONED_CHECK(page); })
352#define PF_NO_TAIL(page, enforce) ({ \
353 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
354 PF_POISONED_CHECK(compound_head(page)); })
355#define PF_NO_COMPOUND(page, enforce) ({ \
356 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
357 PF_POISONED_CHECK(page); })
358#define PF_SECOND(page, enforce) ({ \
359 VM_BUG_ON_PGFLAGS(!PageHead(page), page); \
360 PF_POISONED_CHECK(&page[1]); })
361
362/* Which page is the flag stored in */
363#define FOLIO_PF_ANY 0
364#define FOLIO_PF_HEAD 0
365#define FOLIO_PF_ONLY_HEAD 0
366#define FOLIO_PF_NO_TAIL 0
367#define FOLIO_PF_NO_COMPOUND 0
368#define FOLIO_PF_SECOND 1
369
370/*
371 * Macros to create function definitions for page flags
372 */
373#define TESTPAGEFLAG(uname, lname, policy) \
374static __always_inline bool folio_test_##lname(struct folio *folio) \
375{ return test_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
376static __always_inline int Page##uname(struct page *page) \
377{ return test_bit(PG_##lname, &policy(page, 0)->flags); }
378
379#define SETPAGEFLAG(uname, lname, policy) \
380static __always_inline \
381void folio_set_##lname(struct folio *folio) \
382{ set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
383static __always_inline void SetPage##uname(struct page *page) \
384{ set_bit(PG_##lname, &policy(page, 1)->flags); }
385
386#define CLEARPAGEFLAG(uname, lname, policy) \
387static __always_inline \
388void folio_clear_##lname(struct folio *folio) \
389{ clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
390static __always_inline void ClearPage##uname(struct page *page) \
391{ clear_bit(PG_##lname, &policy(page, 1)->flags); }
392
393#define __SETPAGEFLAG(uname, lname, policy) \
394static __always_inline \
395void __folio_set_##lname(struct folio *folio) \
396{ __set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
397static __always_inline void __SetPage##uname(struct page *page) \
398{ __set_bit(PG_##lname, &policy(page, 1)->flags); }
399
400#define __CLEARPAGEFLAG(uname, lname, policy) \
401static __always_inline \
402void __folio_clear_##lname(struct folio *folio) \
403{ __clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
404static __always_inline void __ClearPage##uname(struct page *page) \
405{ __clear_bit(PG_##lname, &policy(page, 1)->flags); }
406
407#define TESTSETFLAG(uname, lname, policy) \
408static __always_inline \
409bool folio_test_set_##lname(struct folio *folio) \
410{ return test_and_set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
411static __always_inline int TestSetPage##uname(struct page *page) \
412{ return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
413
414#define TESTCLEARFLAG(uname, lname, policy) \
415static __always_inline \
416bool folio_test_clear_##lname(struct folio *folio) \
417{ return test_and_clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
418static __always_inline int TestClearPage##uname(struct page *page) \
419{ return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
420
421#define PAGEFLAG(uname, lname, policy) \
422 TESTPAGEFLAG(uname, lname, policy) \
423 SETPAGEFLAG(uname, lname, policy) \
424 CLEARPAGEFLAG(uname, lname, policy)
425
426#define __PAGEFLAG(uname, lname, policy) \
427 TESTPAGEFLAG(uname, lname, policy) \
428 __SETPAGEFLAG(uname, lname, policy) \
429 __CLEARPAGEFLAG(uname, lname, policy)
430
431#define TESTSCFLAG(uname, lname, policy) \
432 TESTSETFLAG(uname, lname, policy) \
433 TESTCLEARFLAG(uname, lname, policy)
434
435#define TESTPAGEFLAG_FALSE(uname, lname) \
436static inline bool folio_test_##lname(const struct folio *folio) { return false; } \
437static inline int Page##uname(const struct page *page) { return 0; }
438
439#define SETPAGEFLAG_NOOP(uname, lname) \
440static inline void folio_set_##lname(struct folio *folio) { } \
441static inline void SetPage##uname(struct page *page) { }
442
443#define CLEARPAGEFLAG_NOOP(uname, lname) \
444static inline void folio_clear_##lname(struct folio *folio) { } \
445static inline void ClearPage##uname(struct page *page) { }
446
447#define __CLEARPAGEFLAG_NOOP(uname, lname) \
448static inline void __folio_clear_##lname(struct folio *folio) { } \
449static inline void __ClearPage##uname(struct page *page) { }
450
451#define TESTSETFLAG_FALSE(uname, lname) \
452static inline bool folio_test_set_##lname(struct folio *folio) \
453{ return 0; } \
454static inline int TestSetPage##uname(struct page *page) { return 0; }
455
456#define TESTCLEARFLAG_FALSE(uname, lname) \
457static inline bool folio_test_clear_##lname(struct folio *folio) \
458{ return 0; } \
459static inline int TestClearPage##uname(struct page *page) { return 0; }
460
461#define PAGEFLAG_FALSE(uname, lname) TESTPAGEFLAG_FALSE(uname, lname) \
462 SETPAGEFLAG_NOOP(uname, lname) CLEARPAGEFLAG_NOOP(uname, lname)
463
464#define TESTSCFLAG_FALSE(uname, lname) \
465 TESTSETFLAG_FALSE(uname, lname) TESTCLEARFLAG_FALSE(uname, lname)
466
467__PAGEFLAG(Locked, locked, PF_NO_TAIL)
468PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
469PAGEFLAG(Error, error, PF_NO_TAIL) TESTCLEARFLAG(Error, error, PF_NO_TAIL)
470PAGEFLAG(Referenced, referenced, PF_HEAD)
471 TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
472 __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
473PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
474 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
475PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
476 TESTCLEARFLAG(LRU, lru, PF_HEAD)
477PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
478 TESTCLEARFLAG(Active, active, PF_HEAD)
479PAGEFLAG(Workingset, workingset, PF_HEAD)
480 TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
481__PAGEFLAG(Slab, slab, PF_NO_TAIL)
482PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
483
484/* Xen */
485PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
486 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
487PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
488PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
489PAGEFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
490 TESTCLEARFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
491
492PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
493 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
494 __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
495PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
496 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
497 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
498
499/*
500 * Private page markings that may be used by the filesystem that owns the page
501 * for its own purposes.
502 * - PG_private and PG_private_2 cause release_folio() and co to be invoked
503 */
504PAGEFLAG(Private, private, PF_ANY)
505PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
506PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
507 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
508
509/*
510 * Only test-and-set exist for PG_writeback. The unconditional operators are
511 * risky: they bypass page accounting.
512 */
513TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL)
514 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)
515PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
516
517/* PG_readahead is only used for reads; PG_reclaim is only for writes */
518PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
519 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
520PAGEFLAG(Readahead, readahead, PF_NO_COMPOUND)
521 TESTCLEARFLAG(Readahead, readahead, PF_NO_COMPOUND)
522
523#ifdef CONFIG_HIGHMEM
524/*
525 * Must use a macro here due to header dependency issues. page_zone() is not
526 * available at this point.
527 */
528#define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
529#define folio_test_highmem(__f) is_highmem_idx(folio_zonenum(__f))
530#else
531PAGEFLAG_FALSE(HighMem, highmem)
532#endif
533
534#ifdef CONFIG_SWAP
535static __always_inline bool folio_test_swapcache(struct folio *folio)
536{
537 return folio_test_swapbacked(folio) &&
538 test_bit(PG_swapcache, folio_flags(folio, 0));
539}
540
541static __always_inline bool PageSwapCache(struct page *page)
542{
543 return folio_test_swapcache(page_folio(page));
544}
545
546SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
547CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
548#else
549PAGEFLAG_FALSE(SwapCache, swapcache)
550#endif
551
552PAGEFLAG(Unevictable, unevictable, PF_HEAD)
553 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
554 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
555
556#ifdef CONFIG_MMU
557PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
558 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
559 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
560#else
561PAGEFLAG_FALSE(Mlocked, mlocked) __CLEARPAGEFLAG_NOOP(Mlocked, mlocked)
562 TESTSCFLAG_FALSE(Mlocked, mlocked)
563#endif
564
565#ifdef CONFIG_ARCH_USES_PG_UNCACHED
566PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
567#else
568PAGEFLAG_FALSE(Uncached, uncached)
569#endif
570
571#ifdef CONFIG_MEMORY_FAILURE
572PAGEFLAG(HWPoison, hwpoison, PF_ANY)
573TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
574#define __PG_HWPOISON (1UL << PG_hwpoison)
575#define MAGIC_HWPOISON 0x48575053U /* HWPS */
576extern void SetPageHWPoisonTakenOff(struct page *page);
577extern void ClearPageHWPoisonTakenOff(struct page *page);
578extern bool take_page_off_buddy(struct page *page);
579extern bool put_page_back_buddy(struct page *page);
580#else
581PAGEFLAG_FALSE(HWPoison, hwpoison)
582#define __PG_HWPOISON 0
583#endif
584
585#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
586TESTPAGEFLAG(Young, young, PF_ANY)
587SETPAGEFLAG(Young, young, PF_ANY)
588TESTCLEARFLAG(Young, young, PF_ANY)
589PAGEFLAG(Idle, idle, PF_ANY)
590#endif
591
592/*
593 * PageReported() is used to track reported free pages within the Buddy
594 * allocator. We can use the non-atomic version of the test and set
595 * operations as both should be shielded with the zone lock to prevent
596 * any possible races on the setting or clearing of the bit.
597 */
598__PAGEFLAG(Reported, reported, PF_NO_COMPOUND)
599
600#ifdef CONFIG_MEMORY_HOTPLUG
601PAGEFLAG(VmemmapSelfHosted, vmemmap_self_hosted, PF_ANY)
602#else
603PAGEFLAG_FALSE(VmemmapSelfHosted, vmemmap_self_hosted)
604#endif
605
606/*
607 * On an anonymous page mapped into a user virtual memory area,
608 * page->mapping points to its anon_vma, not to a struct address_space;
609 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
610 *
611 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
612 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
613 * bit; and then page->mapping points, not to an anon_vma, but to a private
614 * structure which KSM associates with that merged page. See ksm.h.
615 *
616 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
617 * page and then page->mapping points to a struct movable_operations.
618 *
619 * Please note that, confusingly, "page_mapping" refers to the inode
620 * address_space which maps the page from disk; whereas "page_mapped"
621 * refers to user virtual address space into which the page is mapped.
622 *
623 * For slab pages, since slab reuses the bits in struct page to store its
624 * internal states, the page->mapping does not exist as such, nor do these
625 * flags below. So in order to avoid testing non-existent bits, please
626 * make sure that PageSlab(page) actually evaluates to false before calling
627 * the following functions (e.g., PageAnon). See mm/slab.h.
628 */
629#define PAGE_MAPPING_ANON 0x1
630#define PAGE_MAPPING_MOVABLE 0x2
631#define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
632#define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
633
634/*
635 * Different with flags above, this flag is used only for fsdax mode. It
636 * indicates that this page->mapping is now under reflink case.
637 */
638#define PAGE_MAPPING_DAX_SHARED ((void *)0x1)
639
640static __always_inline bool folio_mapping_flags(struct folio *folio)
641{
642 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) != 0;
643}
644
645static __always_inline int PageMappingFlags(struct page *page)
646{
647 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
648}
649
650static __always_inline bool folio_test_anon(struct folio *folio)
651{
652 return ((unsigned long)folio->mapping & PAGE_MAPPING_ANON) != 0;
653}
654
655static __always_inline bool PageAnon(struct page *page)
656{
657 return folio_test_anon(page_folio(page));
658}
659
660static __always_inline bool __folio_test_movable(const struct folio *folio)
661{
662 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
663 PAGE_MAPPING_MOVABLE;
664}
665
666static __always_inline int __PageMovable(struct page *page)
667{
668 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
669 PAGE_MAPPING_MOVABLE;
670}
671
672#ifdef CONFIG_KSM
673/*
674 * A KSM page is one of those write-protected "shared pages" or "merged pages"
675 * which KSM maps into multiple mms, wherever identical anonymous page content
676 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
677 * anon_vma, but to that page's node of the stable tree.
678 */
679static __always_inline bool folio_test_ksm(struct folio *folio)
680{
681 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
682 PAGE_MAPPING_KSM;
683}
684
685static __always_inline bool PageKsm(struct page *page)
686{
687 return folio_test_ksm(page_folio(page));
688}
689#else
690TESTPAGEFLAG_FALSE(Ksm, ksm)
691#endif
692
693u64 stable_page_flags(struct page *page);
694
695/**
696 * folio_xor_flags_has_waiters - Change some folio flags.
697 * @folio: The folio.
698 * @mask: Bits set in this word will be changed.
699 *
700 * This must only be used for flags which are changed with the folio
701 * lock held. For example, it is unsafe to use for PG_dirty as that
702 * can be set without the folio lock held. It can also only be used
703 * on flags which are in the range 0-6 as some of the implementations
704 * only affect those bits.
705 *
706 * Return: Whether there are tasks waiting on the folio.
707 */
708static inline bool folio_xor_flags_has_waiters(struct folio *folio,
709 unsigned long mask)
710{
711 return xor_unlock_is_negative_byte(mask, addr: folio_flags(folio, n: 0));
712}
713
714/**
715 * folio_test_uptodate - Is this folio up to date?
716 * @folio: The folio.
717 *
718 * The uptodate flag is set on a folio when every byte in the folio is
719 * at least as new as the corresponding bytes on storage. Anonymous
720 * and CoW folios are always uptodate. If the folio is not uptodate,
721 * some of the bytes in it may be; see the is_partially_uptodate()
722 * address_space operation.
723 */
724static inline bool folio_test_uptodate(struct folio *folio)
725{
726 bool ret = test_bit(PG_uptodate, folio_flags(folio, 0));
727 /*
728 * Must ensure that the data we read out of the folio is loaded
729 * _after_ we've loaded folio->flags to check the uptodate bit.
730 * We can skip the barrier if the folio is not uptodate, because
731 * we wouldn't be reading anything from it.
732 *
733 * See folio_mark_uptodate() for the other side of the story.
734 */
735 if (ret)
736 smp_rmb();
737
738 return ret;
739}
740
741static inline int PageUptodate(struct page *page)
742{
743 return folio_test_uptodate(page_folio(page));
744}
745
746static __always_inline void __folio_mark_uptodate(struct folio *folio)
747{
748 smp_wmb();
749 __set_bit(PG_uptodate, folio_flags(folio, 0));
750}
751
752static __always_inline void folio_mark_uptodate(struct folio *folio)
753{
754 /*
755 * Memory barrier must be issued before setting the PG_uptodate bit,
756 * so that all previous stores issued in order to bring the folio
757 * uptodate are actually visible before folio_test_uptodate becomes true.
758 */
759 smp_wmb();
760 set_bit(nr: PG_uptodate, addr: folio_flags(folio, n: 0));
761}
762
763static __always_inline void __SetPageUptodate(struct page *page)
764{
765 __folio_mark_uptodate(folio: (struct folio *)page);
766}
767
768static __always_inline void SetPageUptodate(struct page *page)
769{
770 folio_mark_uptodate(folio: (struct folio *)page);
771}
772
773CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
774
775bool __folio_start_writeback(struct folio *folio, bool keep_write);
776bool set_page_writeback(struct page *page);
777
778#define folio_start_writeback(folio) \
779 __folio_start_writeback(folio, false)
780#define folio_start_writeback_keepwrite(folio) \
781 __folio_start_writeback(folio, true)
782
783static inline bool test_set_page_writeback(struct page *page)
784{
785 return set_page_writeback(page);
786}
787
788static __always_inline bool folio_test_head(struct folio *folio)
789{
790 return test_bit(PG_head, folio_flags(folio, FOLIO_PF_ANY));
791}
792
793static __always_inline int PageHead(struct page *page)
794{
795 PF_POISONED_CHECK(page);
796 return test_bit(PG_head, &page->flags) && !page_is_fake_head(page);
797}
798
799__SETPAGEFLAG(Head, head, PF_ANY)
800__CLEARPAGEFLAG(Head, head, PF_ANY)
801CLEARPAGEFLAG(Head, head, PF_ANY)
802
803/**
804 * folio_test_large() - Does this folio contain more than one page?
805 * @folio: The folio to test.
806 *
807 * Return: True if the folio is larger than one page.
808 */
809static inline bool folio_test_large(struct folio *folio)
810{
811 return folio_test_head(folio);
812}
813
814static __always_inline void set_compound_head(struct page *page, struct page *head)
815{
816 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
817}
818
819static __always_inline void clear_compound_head(struct page *page)
820{
821 WRITE_ONCE(page->compound_head, 0);
822}
823
824#ifdef CONFIG_TRANSPARENT_HUGEPAGE
825static inline void ClearPageCompound(struct page *page)
826{
827 BUG_ON(!PageHead(page));
828 ClearPageHead(page);
829}
830PAGEFLAG(LargeRmappable, large_rmappable, PF_SECOND)
831#else
832TESTPAGEFLAG_FALSE(LargeRmappable, large_rmappable)
833#endif
834
835#define PG_head_mask ((1UL << PG_head))
836
837#ifdef CONFIG_HUGETLB_PAGE
838int PageHuge(struct page *page);
839SETPAGEFLAG(HugeTLB, hugetlb, PF_SECOND)
840CLEARPAGEFLAG(HugeTLB, hugetlb, PF_SECOND)
841
842/**
843 * folio_test_hugetlb - Determine if the folio belongs to hugetlbfs
844 * @folio: The folio to test.
845 *
846 * Context: Any context. Caller should have a reference on the folio to
847 * prevent it from being turned into a tail page.
848 * Return: True for hugetlbfs folios, false for anon folios or folios
849 * belonging to other filesystems.
850 */
851static inline bool folio_test_hugetlb(struct folio *folio)
852{
853 return folio_test_large(folio) &&
854 test_bit(PG_hugetlb, folio_flags(folio, 1));
855}
856#else
857TESTPAGEFLAG_FALSE(Huge, hugetlb)
858#endif
859
860#ifdef CONFIG_TRANSPARENT_HUGEPAGE
861/*
862 * PageHuge() only returns true for hugetlbfs pages, but not for
863 * normal or transparent huge pages.
864 *
865 * PageTransHuge() returns true for both transparent huge and
866 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
867 * called only in the core VM paths where hugetlbfs pages can't exist.
868 */
869static inline int PageTransHuge(struct page *page)
870{
871 VM_BUG_ON_PAGE(PageTail(page), page);
872 return PageHead(page);
873}
874
875/*
876 * PageTransCompound returns true for both transparent huge pages
877 * and hugetlbfs pages, so it should only be called when it's known
878 * that hugetlbfs pages aren't involved.
879 */
880static inline int PageTransCompound(struct page *page)
881{
882 return PageCompound(page);
883}
884
885/*
886 * PageTransTail returns true for both transparent huge pages
887 * and hugetlbfs pages, so it should only be called when it's known
888 * that hugetlbfs pages aren't involved.
889 */
890static inline int PageTransTail(struct page *page)
891{
892 return PageTail(page);
893}
894#else
895TESTPAGEFLAG_FALSE(TransHuge, transhuge)
896TESTPAGEFLAG_FALSE(TransCompound, transcompound)
897TESTPAGEFLAG_FALSE(TransCompoundMap, transcompoundmap)
898TESTPAGEFLAG_FALSE(TransTail, transtail)
899#endif
900
901#if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
902/*
903 * PageHasHWPoisoned indicates that at least one subpage is hwpoisoned in the
904 * compound page.
905 *
906 * This flag is set by hwpoison handler. Cleared by THP split or free page.
907 */
908PAGEFLAG(HasHWPoisoned, has_hwpoisoned, PF_SECOND)
909 TESTSCFLAG(HasHWPoisoned, has_hwpoisoned, PF_SECOND)
910#else
911PAGEFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
912 TESTSCFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
913#endif
914
915/*
916 * Check if a page is currently marked HWPoisoned. Note that this check is
917 * best effort only and inherently racy: there is no way to synchronize with
918 * failing hardware.
919 */
920static inline bool is_page_hwpoison(struct page *page)
921{
922 if (PageHWPoison(page))
923 return true;
924 return PageHuge(page) && PageHWPoison(compound_head(page));
925}
926
927/*
928 * For pages that are never mapped to userspace (and aren't PageSlab),
929 * page_type may be used. Because it is initialised to -1, we invert the
930 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
931 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
932 * low bits so that an underflow or overflow of page_mapcount() won't be
933 * mistaken for a page type value.
934 */
935
936#define PAGE_TYPE_BASE 0xf0000000
937/* Reserve 0x0000007f to catch underflows of page_mapcount */
938#define PAGE_MAPCOUNT_RESERVE -128
939#define PG_buddy 0x00000080
940#define PG_offline 0x00000100
941#define PG_table 0x00000200
942#define PG_guard 0x00000400
943
944#define PageType(page, flag) \
945 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
946#define folio_test_type(folio, flag) \
947 ((folio->page.page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
948
949static inline int page_type_has_type(unsigned int page_type)
950{
951 return (int)page_type < PAGE_MAPCOUNT_RESERVE;
952}
953
954static inline int page_has_type(struct page *page)
955{
956 return page_type_has_type(page_type: page->page_type);
957}
958
959#define PAGE_TYPE_OPS(uname, lname, fname) \
960static __always_inline int Page##uname(const struct page *page) \
961{ \
962 return PageType(page, PG_##lname); \
963} \
964static __always_inline int folio_test_##fname(const struct folio *folio)\
965{ \
966 return folio_test_type(folio, PG_##lname); \
967} \
968static __always_inline void __SetPage##uname(struct page *page) \
969{ \
970 VM_BUG_ON_PAGE(!PageType(page, 0), page); \
971 page->page_type &= ~PG_##lname; \
972} \
973static __always_inline void __folio_set_##fname(struct folio *folio) \
974{ \
975 VM_BUG_ON_FOLIO(!folio_test_type(folio, 0), folio); \
976 folio->page.page_type &= ~PG_##lname; \
977} \
978static __always_inline void __ClearPage##uname(struct page *page) \
979{ \
980 VM_BUG_ON_PAGE(!Page##uname(page), page); \
981 page->page_type |= PG_##lname; \
982} \
983static __always_inline void __folio_clear_##fname(struct folio *folio) \
984{ \
985 VM_BUG_ON_FOLIO(!folio_test_##fname(folio), folio); \
986 folio->page.page_type |= PG_##lname; \
987} \
988
989/*
990 * PageBuddy() indicates that the page is free and in the buddy system
991 * (see mm/page_alloc.c).
992 */
993PAGE_TYPE_OPS(Buddy, buddy, buddy)
994
995/*
996 * PageOffline() indicates that the page is logically offline although the
997 * containing section is online. (e.g. inflated in a balloon driver or
998 * not onlined when onlining the section).
999 * The content of these pages is effectively stale. Such pages should not
1000 * be touched (read/write/dump/save) except by their owner.
1001 *
1002 * If a driver wants to allow to offline unmovable PageOffline() pages without
1003 * putting them back to the buddy, it can do so via the memory notifier by
1004 * decrementing the reference count in MEM_GOING_OFFLINE and incrementing the
1005 * reference count in MEM_CANCEL_OFFLINE. When offlining, the PageOffline()
1006 * pages (now with a reference count of zero) are treated like free pages,
1007 * allowing the containing memory block to get offlined. A driver that
1008 * relies on this feature is aware that re-onlining the memory block will
1009 * require to re-set the pages PageOffline() and not giving them to the
1010 * buddy via online_page_callback_t.
1011 *
1012 * There are drivers that mark a page PageOffline() and expect there won't be
1013 * any further access to page content. PFN walkers that read content of random
1014 * pages should check PageOffline() and synchronize with such drivers using
1015 * page_offline_freeze()/page_offline_thaw().
1016 */
1017PAGE_TYPE_OPS(Offline, offline, offline)
1018
1019extern void page_offline_freeze(void);
1020extern void page_offline_thaw(void);
1021extern void page_offline_begin(void);
1022extern void page_offline_end(void);
1023
1024/*
1025 * Marks pages in use as page tables.
1026 */
1027PAGE_TYPE_OPS(Table, table, pgtable)
1028
1029/*
1030 * Marks guardpages used with debug_pagealloc.
1031 */
1032PAGE_TYPE_OPS(Guard, guard, guard)
1033
1034extern bool is_free_buddy_page(struct page *page);
1035
1036PAGEFLAG(Isolated, isolated, PF_ANY);
1037
1038static __always_inline int PageAnonExclusive(struct page *page)
1039{
1040 VM_BUG_ON_PGFLAGS(!PageAnon(page), page);
1041 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1042 return test_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1043}
1044
1045static __always_inline void SetPageAnonExclusive(struct page *page)
1046{
1047 VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
1048 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1049 set_bit(nr: PG_anon_exclusive, addr: &PF_ANY(page, 1)->flags);
1050}
1051
1052static __always_inline void ClearPageAnonExclusive(struct page *page)
1053{
1054 VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
1055 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1056 clear_bit(nr: PG_anon_exclusive, addr: &PF_ANY(page, 1)->flags);
1057}
1058
1059static __always_inline void __ClearPageAnonExclusive(struct page *page)
1060{
1061 VM_BUG_ON_PGFLAGS(!PageAnon(page), page);
1062 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1063 __clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1064}
1065
1066#ifdef CONFIG_MMU
1067#define __PG_MLOCKED (1UL << PG_mlocked)
1068#else
1069#define __PG_MLOCKED 0
1070#endif
1071
1072/*
1073 * Flags checked when a page is freed. Pages being freed should not have
1074 * these flags set. If they are, there is a problem.
1075 */
1076#define PAGE_FLAGS_CHECK_AT_FREE \
1077 (1UL << PG_lru | 1UL << PG_locked | \
1078 1UL << PG_private | 1UL << PG_private_2 | \
1079 1UL << PG_writeback | 1UL << PG_reserved | \
1080 1UL << PG_slab | 1UL << PG_active | \
1081 1UL << PG_unevictable | __PG_MLOCKED | LRU_GEN_MASK)
1082
1083/*
1084 * Flags checked when a page is prepped for return by the page allocator.
1085 * Pages being prepped should not have these flags set. If they are set,
1086 * there has been a kernel bug or struct page corruption.
1087 *
1088 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
1089 * alloc-free cycle to prevent from reusing the page.
1090 */
1091#define PAGE_FLAGS_CHECK_AT_PREP \
1092 ((PAGEFLAGS_MASK & ~__PG_HWPOISON) | LRU_GEN_MASK | LRU_REFS_MASK)
1093
1094/*
1095 * Flags stored in the second page of a compound page. They may overlap
1096 * the CHECK_AT_FREE flags above, so need to be cleared.
1097 */
1098#define PAGE_FLAGS_SECOND \
1099 (0xffUL /* order */ | 1UL << PG_has_hwpoisoned | \
1100 1UL << PG_hugetlb | 1UL << PG_large_rmappable)
1101
1102#define PAGE_FLAGS_PRIVATE \
1103 (1UL << PG_private | 1UL << PG_private_2)
1104/**
1105 * page_has_private - Determine if page has private stuff
1106 * @page: The page to be checked
1107 *
1108 * Determine if a page has private stuff, indicating that release routines
1109 * should be invoked upon it.
1110 */
1111static inline int page_has_private(struct page *page)
1112{
1113 return !!(page->flags & PAGE_FLAGS_PRIVATE);
1114}
1115
1116static inline bool folio_has_private(struct folio *folio)
1117{
1118 return page_has_private(page: &folio->page);
1119}
1120
1121#undef PF_ANY
1122#undef PF_HEAD
1123#undef PF_ONLY_HEAD
1124#undef PF_NO_TAIL
1125#undef PF_NO_COMPOUND
1126#undef PF_SECOND
1127#endif /* !__GENERATING_BOUNDS_H */
1128
1129#endif /* PAGE_FLAGS_H */
1130

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