1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Macros for manipulating and testing page->flags
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 */
18 * Various page->flags bits:
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,
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!
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
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).
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.
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.
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.
60 * PG_locked also pins a page in pagecache, and blocks truncation of the file
63 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
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).
71 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
72 * file-backed pagecache (see mm/vmscan.c).
74 * PG_error is set to indicate that an I/O error occurred on this page.
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
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!
86 * Don't use the pageflags directly. Use the PageFoo macros.
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.
92 * | FIELD | ... | FLAGS |
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).
101 PG_locked, /* Page is locked. Don't touch. */
108 PG_waiters, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
111 PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
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" */
123 PG_mlocked, /* Page is vma mlocked */
125 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
126 PG_uncached, /* Page has been mapped as uncached */
128 #ifdef CONFIG_MEMORY_FAILURE
129 PG_hwpoison, /* hardware poisoned page. Don't touch */
131 #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
135 #ifdef CONFIG_ARCH_USES_PG_ARCH_X
139 #ifdef CONFIG_KASAN_HW_TAGS
140 PG_skip_kasan_poison,
144 PG_readahead = PG_reclaim,
147 * Depending on the way an anonymous folio can be mapped into a page
148 * table (e.g., single PMD/PUD/CONT of the head page vs. PTE-mapped
149 * THP), PG_anon_exclusive may be set only for the head page or for
150 * tail pages of an anonymous folio. For now, we only expect it to be
151 * set on tail pages for PTE-mapped THP.
153 PG_anon_exclusive = PG_mappedtodisk,
156 PG_checked = PG_owner_priv_1,
159 PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */
161 /* Two page bits are conscripted by FS-Cache to maintain local caching
162 * state. These bits are set on pages belonging to the netfs's inodes
163 * when those inodes are being locally cached.
165 PG_fscache = PG_private_2, /* page backed by cache */
168 /* Pinned in Xen as a read-only pagetable page. */
169 PG_pinned = PG_owner_priv_1,
170 /* Pinned as part of domain save (see xen_mm_pin_all()). */
171 PG_savepinned = PG_dirty,
172 /* Has a grant mapping of another (foreign) domain's page. */
173 PG_foreign = PG_owner_priv_1,
174 /* Remapped by swiotlb-xen. */
175 PG_xen_remapped = PG_owner_priv_1,
177 #ifdef CONFIG_MEMORY_FAILURE
179 * Compound pages. Stored in first tail page's flags.
180 * Indicates that at least one subpage is hwpoisoned in the
183 PG_has_hwpoisoned = PG_error,
186 /* non-lru isolated movable page */
187 PG_isolated = PG_reclaim,
189 /* Only valid for buddy pages. Used to track pages that are reported */
190 PG_reported = PG_uptodate,
192 #ifdef CONFIG_MEMORY_HOTPLUG
193 /* For self-hosted memmap pages */
194 PG_vmemmap_self_hosted = PG_owner_priv_1,
198 #define PAGEFLAGS_MASK ((1UL << NR_PAGEFLAGS) - 1)
200 #ifndef __GENERATING_BOUNDS_H
202 #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
203 DECLARE_STATIC_KEY_FALSE(hugetlb_optimize_vmemmap_key);
206 * Return the real head page struct iff the @page is a fake head page, otherwise
207 * return the @page itself. See Documentation/mm/vmemmap_dedup.rst.
209 static __always_inline const struct page *page_fixed_fake_head(const struct page *page)
211 if (!static_branch_unlikely(&hugetlb_optimize_vmemmap_key))
215 * Only addresses aligned with PAGE_SIZE of struct page may be fake head
216 * struct page. The alignment check aims to avoid access the fields (
217 * e.g. compound_head) of the @page[1]. It can avoid touch a (possibly)
218 * cold cacheline in some cases.
220 if (IS_ALIGNED((unsigned long)page, PAGE_SIZE) &&
221 test_bit(PG_head, &page->flags)) {
223 * We can safely access the field of the @page[1] with PG_head
224 * because the @page is a compound page composed with at least
225 * two contiguous pages.
227 unsigned long head = READ_ONCE(page[1].compound_head);
229 if (likely(head & 1))
230 return (const struct page *)(head - 1);
235 static inline const struct page *page_fixed_fake_head(const struct page *page)
241 static __always_inline int page_is_fake_head(struct page *page)
243 return page_fixed_fake_head(page) != page;
246 static inline unsigned long _compound_head(const struct page *page)
248 unsigned long head = READ_ONCE(page->compound_head);
250 if (unlikely(head & 1))
252 return (unsigned long)page_fixed_fake_head(page);
255 #define compound_head(page) ((typeof(page))_compound_head(page))
258 * page_folio - Converts from page to folio.
261 * Every page is part of a folio. This function cannot be called on a
264 * Context: No reference, nor lock is required on @page. If the caller
265 * does not hold a reference, this call may race with a folio split, so
266 * it should re-check the folio still contains this page after gaining
267 * a reference on the folio.
268 * Return: The folio which contains this page.
270 #define page_folio(p) (_Generic((p), \
271 const struct page *: (const struct folio *)_compound_head(p), \
272 struct page *: (struct folio *)_compound_head(p)))
275 * folio_page - Return a page from a folio.
277 * @n: The page number to return.
279 * @n is relative to the start of the folio. This function does not
280 * check that the page number lies within @folio; the caller is presumed
281 * to have a reference to the page.
283 #define folio_page(folio, n) nth_page(&(folio)->page, n)
285 static __always_inline int PageTail(struct page *page)
287 return READ_ONCE(page->compound_head) & 1 || page_is_fake_head(page);
290 static __always_inline int PageCompound(struct page *page)
292 return test_bit(PG_head, &page->flags) ||
293 READ_ONCE(page->compound_head) & 1;
296 #define PAGE_POISON_PATTERN -1l
297 static inline int PagePoisoned(const struct page *page)
299 return READ_ONCE(page->flags) == PAGE_POISON_PATTERN;
302 #ifdef CONFIG_DEBUG_VM
303 void page_init_poison(struct page *page, size_t size);
305 static inline void page_init_poison(struct page *page, size_t size)
310 static unsigned long *folio_flags(struct folio *folio, unsigned n)
312 struct page *page = &folio->page;
314 VM_BUG_ON_PGFLAGS(PageTail(page), page);
315 VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags), page);
316 return &page[n].flags;
320 * Page flags policies wrt compound pages
323 * check if this struct page poisoned/uninitialized
326 * the page flag is relevant for small, head and tail pages.
329 * for compound page all operations related to the page flag applied to
333 * for compound page, callers only ever operate on the head page.
336 * modifications of the page flag must be done on small or head pages,
337 * checks can be done on tail pages too.
340 * the page flag is not relevant for compound pages.
343 * the page flag is stored in the first tail page.
345 #define PF_POISONED_CHECK(page) ({ \
346 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \
348 #define PF_ANY(page, enforce) PF_POISONED_CHECK(page)
349 #define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page))
350 #define PF_ONLY_HEAD(page, enforce) ({ \
351 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
352 PF_POISONED_CHECK(page); })
353 #define PF_NO_TAIL(page, enforce) ({ \
354 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
355 PF_POISONED_CHECK(compound_head(page)); })
356 #define PF_NO_COMPOUND(page, enforce) ({ \
357 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
358 PF_POISONED_CHECK(page); })
359 #define PF_SECOND(page, enforce) ({ \
360 VM_BUG_ON_PGFLAGS(!PageHead(page), page); \
361 PF_POISONED_CHECK(&page[1]); })
363 /* Which page is the flag stored in */
364 #define FOLIO_PF_ANY 0
365 #define FOLIO_PF_HEAD 0
366 #define FOLIO_PF_ONLY_HEAD 0
367 #define FOLIO_PF_NO_TAIL 0
368 #define FOLIO_PF_NO_COMPOUND 0
369 #define FOLIO_PF_SECOND 1
372 * Macros to create function definitions for page flags
374 #define TESTPAGEFLAG(uname, lname, policy) \
375 static __always_inline bool folio_test_##lname(struct folio *folio) \
376 { return test_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
377 static __always_inline int Page##uname(struct page *page) \
378 { return test_bit(PG_##lname, &policy(page, 0)->flags); }
380 #define SETPAGEFLAG(uname, lname, policy) \
381 static __always_inline \
382 void folio_set_##lname(struct folio *folio) \
383 { set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
384 static __always_inline void SetPage##uname(struct page *page) \
385 { set_bit(PG_##lname, &policy(page, 1)->flags); }
387 #define CLEARPAGEFLAG(uname, lname, policy) \
388 static __always_inline \
389 void folio_clear_##lname(struct folio *folio) \
390 { clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
391 static __always_inline void ClearPage##uname(struct page *page) \
392 { clear_bit(PG_##lname, &policy(page, 1)->flags); }
394 #define __SETPAGEFLAG(uname, lname, policy) \
395 static __always_inline \
396 void __folio_set_##lname(struct folio *folio) \
397 { __set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
398 static __always_inline void __SetPage##uname(struct page *page) \
399 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
401 #define __CLEARPAGEFLAG(uname, lname, policy) \
402 static __always_inline \
403 void __folio_clear_##lname(struct folio *folio) \
404 { __clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
405 static __always_inline void __ClearPage##uname(struct page *page) \
406 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
408 #define TESTSETFLAG(uname, lname, policy) \
409 static __always_inline \
410 bool folio_test_set_##lname(struct folio *folio) \
411 { return test_and_set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
412 static __always_inline int TestSetPage##uname(struct page *page) \
413 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
415 #define TESTCLEARFLAG(uname, lname, policy) \
416 static __always_inline \
417 bool folio_test_clear_##lname(struct folio *folio) \
418 { return test_and_clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
419 static __always_inline int TestClearPage##uname(struct page *page) \
420 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
422 #define PAGEFLAG(uname, lname, policy) \
423 TESTPAGEFLAG(uname, lname, policy) \
424 SETPAGEFLAG(uname, lname, policy) \
425 CLEARPAGEFLAG(uname, lname, policy)
427 #define __PAGEFLAG(uname, lname, policy) \
428 TESTPAGEFLAG(uname, lname, policy) \
429 __SETPAGEFLAG(uname, lname, policy) \
430 __CLEARPAGEFLAG(uname, lname, policy)
432 #define TESTSCFLAG(uname, lname, policy) \
433 TESTSETFLAG(uname, lname, policy) \
434 TESTCLEARFLAG(uname, lname, policy)
436 #define TESTPAGEFLAG_FALSE(uname, lname) \
437 static inline bool folio_test_##lname(const struct folio *folio) { return false; } \
438 static inline int Page##uname(const struct page *page) { return 0; }
440 #define SETPAGEFLAG_NOOP(uname, lname) \
441 static inline void folio_set_##lname(struct folio *folio) { } \
442 static inline void SetPage##uname(struct page *page) { }
444 #define CLEARPAGEFLAG_NOOP(uname, lname) \
445 static inline void folio_clear_##lname(struct folio *folio) { } \
446 static inline void ClearPage##uname(struct page *page) { }
448 #define __CLEARPAGEFLAG_NOOP(uname, lname) \
449 static inline void __folio_clear_##lname(struct folio *folio) { } \
450 static inline void __ClearPage##uname(struct page *page) { }
452 #define TESTSETFLAG_FALSE(uname, lname) \
453 static inline bool folio_test_set_##lname(struct folio *folio) \
455 static inline int TestSetPage##uname(struct page *page) { return 0; }
457 #define TESTCLEARFLAG_FALSE(uname, lname) \
458 static inline bool folio_test_clear_##lname(struct folio *folio) \
460 static inline int TestClearPage##uname(struct page *page) { return 0; }
462 #define PAGEFLAG_FALSE(uname, lname) TESTPAGEFLAG_FALSE(uname, lname) \
463 SETPAGEFLAG_NOOP(uname, lname) CLEARPAGEFLAG_NOOP(uname, lname)
465 #define TESTSCFLAG_FALSE(uname, lname) \
466 TESTSETFLAG_FALSE(uname, lname) TESTCLEARFLAG_FALSE(uname, lname)
468 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
469 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
470 PAGEFLAG(Error, error, PF_NO_TAIL) TESTCLEARFLAG(Error, error, PF_NO_TAIL)
471 PAGEFLAG(Referenced, referenced, PF_HEAD)
472 TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
473 __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
474 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
475 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
476 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
477 TESTCLEARFLAG(LRU, lru, PF_HEAD)
478 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
479 TESTCLEARFLAG(Active, active, PF_HEAD)
480 PAGEFLAG(Workingset, workingset, PF_HEAD)
481 TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
482 __PAGEFLAG(Slab, slab, PF_NO_TAIL)
483 PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
486 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
487 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
488 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
489 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
490 PAGEFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
491 TESTCLEARFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
493 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
494 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
495 __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
496 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
497 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
498 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
501 * Private page markings that may be used by the filesystem that owns the page
502 * for its own purposes.
503 * - PG_private and PG_private_2 cause release_folio() and co to be invoked
505 PAGEFLAG(Private, private, PF_ANY)
506 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
507 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
508 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
511 * Only test-and-set exist for PG_writeback. The unconditional operators are
512 * risky: they bypass page accounting.
514 TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL)
515 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)
516 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
518 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
519 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
520 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
521 PAGEFLAG(Readahead, readahead, PF_NO_COMPOUND)
522 TESTCLEARFLAG(Readahead, readahead, PF_NO_COMPOUND)
524 #ifdef CONFIG_HIGHMEM
526 * Must use a macro here due to header dependency issues. page_zone() is not
527 * available at this point.
529 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
530 #define folio_test_highmem(__f) is_highmem_idx(folio_zonenum(__f))
532 PAGEFLAG_FALSE(HighMem, highmem)
536 static __always_inline bool folio_test_swapcache(struct folio *folio)
538 return folio_test_swapbacked(folio) &&
539 test_bit(PG_swapcache, folio_flags(folio, 0));
542 static __always_inline bool PageSwapCache(struct page *page)
544 return folio_test_swapcache(page_folio(page));
547 SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
548 CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
550 PAGEFLAG_FALSE(SwapCache, swapcache)
553 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
554 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
555 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
558 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
559 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
560 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
562 PAGEFLAG_FALSE(Mlocked, mlocked) __CLEARPAGEFLAG_NOOP(Mlocked, mlocked)
563 TESTSCFLAG_FALSE(Mlocked, mlocked)
566 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
567 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
569 PAGEFLAG_FALSE(Uncached, uncached)
572 #ifdef CONFIG_MEMORY_FAILURE
573 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
574 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
575 #define __PG_HWPOISON (1UL << PG_hwpoison)
576 #define MAGIC_HWPOISON 0x48575053U /* HWPS */
577 extern void SetPageHWPoisonTakenOff(struct page *page);
578 extern void ClearPageHWPoisonTakenOff(struct page *page);
579 extern bool take_page_off_buddy(struct page *page);
580 extern bool put_page_back_buddy(struct page *page);
582 PAGEFLAG_FALSE(HWPoison, hwpoison)
583 #define __PG_HWPOISON 0
586 #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
587 TESTPAGEFLAG(Young, young, PF_ANY)
588 SETPAGEFLAG(Young, young, PF_ANY)
589 TESTCLEARFLAG(Young, young, PF_ANY)
590 PAGEFLAG(Idle, idle, PF_ANY)
593 #ifdef CONFIG_KASAN_HW_TAGS
594 PAGEFLAG(SkipKASanPoison, skip_kasan_poison, PF_HEAD)
596 PAGEFLAG_FALSE(SkipKASanPoison, skip_kasan_poison)
600 * PageReported() is used to track reported free pages within the Buddy
601 * allocator. We can use the non-atomic version of the test and set
602 * operations as both should be shielded with the zone lock to prevent
603 * any possible races on the setting or clearing of the bit.
605 __PAGEFLAG(Reported, reported, PF_NO_COMPOUND)
607 #ifdef CONFIG_MEMORY_HOTPLUG
608 PAGEFLAG(VmemmapSelfHosted, vmemmap_self_hosted, PF_ANY)
610 PAGEFLAG_FALSE(VmemmapSelfHosted, vmemmap_self_hosted)
614 * On an anonymous page mapped into a user virtual memory area,
615 * page->mapping points to its anon_vma, not to a struct address_space;
616 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
618 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
619 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
620 * bit; and then page->mapping points, not to an anon_vma, but to a private
621 * structure which KSM associates with that merged page. See ksm.h.
623 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
624 * page and then page->mapping points to a struct movable_operations.
626 * Please note that, confusingly, "page_mapping" refers to the inode
627 * address_space which maps the page from disk; whereas "page_mapped"
628 * refers to user virtual address space into which the page is mapped.
630 #define PAGE_MAPPING_ANON 0x1
631 #define PAGE_MAPPING_MOVABLE 0x2
632 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
633 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
636 * Different with flags above, this flag is used only for fsdax mode. It
637 * indicates that this page->mapping is now under reflink case.
639 #define PAGE_MAPPING_DAX_SHARED ((void *)0x1)
641 static __always_inline bool folio_mapping_flags(struct folio *folio)
643 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) != 0;
646 static __always_inline int PageMappingFlags(struct page *page)
648 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
651 static __always_inline bool folio_test_anon(struct folio *folio)
653 return ((unsigned long)folio->mapping & PAGE_MAPPING_ANON) != 0;
656 static __always_inline bool PageAnon(struct page *page)
658 return folio_test_anon(page_folio(page));
661 static __always_inline bool __folio_test_movable(const struct folio *folio)
663 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
664 PAGE_MAPPING_MOVABLE;
667 static __always_inline int __PageMovable(struct page *page)
669 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
670 PAGE_MAPPING_MOVABLE;
675 * A KSM page is one of those write-protected "shared pages" or "merged pages"
676 * which KSM maps into multiple mms, wherever identical anonymous page content
677 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
678 * anon_vma, but to that page's node of the stable tree.
680 static __always_inline bool folio_test_ksm(struct folio *folio)
682 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
686 static __always_inline bool PageKsm(struct page *page)
688 return folio_test_ksm(page_folio(page));
691 TESTPAGEFLAG_FALSE(Ksm, ksm)
694 u64 stable_page_flags(struct page *page);
697 * folio_test_uptodate - Is this folio up to date?
700 * The uptodate flag is set on a folio when every byte in the folio is
701 * at least as new as the corresponding bytes on storage. Anonymous
702 * and CoW folios are always uptodate. If the folio is not uptodate,
703 * some of the bytes in it may be; see the is_partially_uptodate()
704 * address_space operation.
706 static inline bool folio_test_uptodate(struct folio *folio)
708 bool ret = test_bit(PG_uptodate, folio_flags(folio, 0));
710 * Must ensure that the data we read out of the folio is loaded
711 * _after_ we've loaded folio->flags to check the uptodate bit.
712 * We can skip the barrier if the folio is not uptodate, because
713 * we wouldn't be reading anything from it.
715 * See folio_mark_uptodate() for the other side of the story.
723 static inline int PageUptodate(struct page *page)
725 return folio_test_uptodate(page_folio(page));
728 static __always_inline void __folio_mark_uptodate(struct folio *folio)
731 __set_bit(PG_uptodate, folio_flags(folio, 0));
734 static __always_inline void folio_mark_uptodate(struct folio *folio)
737 * Memory barrier must be issued before setting the PG_uptodate bit,
738 * so that all previous stores issued in order to bring the folio
739 * uptodate are actually visible before folio_test_uptodate becomes true.
742 set_bit(PG_uptodate, folio_flags(folio, 0));
745 static __always_inline void __SetPageUptodate(struct page *page)
747 __folio_mark_uptodate((struct folio *)page);
750 static __always_inline void SetPageUptodate(struct page *page)
752 folio_mark_uptodate((struct folio *)page);
755 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
757 bool __folio_start_writeback(struct folio *folio, bool keep_write);
758 bool set_page_writeback(struct page *page);
760 #define folio_start_writeback(folio) \
761 __folio_start_writeback(folio, false)
762 #define folio_start_writeback_keepwrite(folio) \
763 __folio_start_writeback(folio, true)
765 static inline bool test_set_page_writeback(struct page *page)
767 return set_page_writeback(page);
770 static __always_inline bool folio_test_head(struct folio *folio)
772 return test_bit(PG_head, folio_flags(folio, FOLIO_PF_ANY));
775 static __always_inline int PageHead(struct page *page)
777 PF_POISONED_CHECK(page);
778 return test_bit(PG_head, &page->flags) && !page_is_fake_head(page);
781 __SETPAGEFLAG(Head, head, PF_ANY)
782 __CLEARPAGEFLAG(Head, head, PF_ANY)
783 CLEARPAGEFLAG(Head, head, PF_ANY)
786 * folio_test_large() - Does this folio contain more than one page?
787 * @folio: The folio to test.
789 * Return: True if the folio is larger than one page.
791 static inline bool folio_test_large(struct folio *folio)
793 return folio_test_head(folio);
796 static __always_inline void set_compound_head(struct page *page, struct page *head)
798 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
801 static __always_inline void clear_compound_head(struct page *page)
803 WRITE_ONCE(page->compound_head, 0);
806 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
807 static inline void ClearPageCompound(struct page *page)
809 BUG_ON(!PageHead(page));
814 #define PG_head_mask ((1UL << PG_head))
816 #ifdef CONFIG_HUGETLB_PAGE
817 int PageHuge(struct page *page);
818 int PageHeadHuge(struct page *page);
819 static inline bool folio_test_hugetlb(struct folio *folio)
821 return PageHeadHuge(&folio->page);
824 TESTPAGEFLAG_FALSE(Huge, hugetlb)
825 TESTPAGEFLAG_FALSE(HeadHuge, headhuge)
828 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
830 * PageHuge() only returns true for hugetlbfs pages, but not for
831 * normal or transparent huge pages.
833 * PageTransHuge() returns true for both transparent huge and
834 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
835 * called only in the core VM paths where hugetlbfs pages can't exist.
837 static inline int PageTransHuge(struct page *page)
839 VM_BUG_ON_PAGE(PageTail(page), page);
840 return PageHead(page);
843 static inline bool folio_test_transhuge(struct folio *folio)
845 return folio_test_head(folio);
849 * PageTransCompound returns true for both transparent huge pages
850 * and hugetlbfs pages, so it should only be called when it's known
851 * that hugetlbfs pages aren't involved.
853 static inline int PageTransCompound(struct page *page)
855 return PageCompound(page);
859 * PageTransTail 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.
863 static inline int PageTransTail(struct page *page)
865 return PageTail(page);
868 TESTPAGEFLAG_FALSE(TransHuge, transhuge)
869 TESTPAGEFLAG_FALSE(TransCompound, transcompound)
870 TESTPAGEFLAG_FALSE(TransCompoundMap, transcompoundmap)
871 TESTPAGEFLAG_FALSE(TransTail, transtail)
874 #if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
876 * PageHasHWPoisoned indicates that at least one subpage is hwpoisoned in the
879 * This flag is set by hwpoison handler. Cleared by THP split or free page.
881 PAGEFLAG(HasHWPoisoned, has_hwpoisoned, PF_SECOND)
882 TESTSCFLAG(HasHWPoisoned, has_hwpoisoned, PF_SECOND)
884 PAGEFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
885 TESTSCFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
889 * Check if a page is currently marked HWPoisoned. Note that this check is
890 * best effort only and inherently racy: there is no way to synchronize with
893 static inline bool is_page_hwpoison(struct page *page)
895 if (PageHWPoison(page))
897 return PageHuge(page) && PageHWPoison(compound_head(page));
901 * For pages that are never mapped to userspace (and aren't PageSlab),
902 * page_type may be used. Because it is initialised to -1, we invert the
903 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
904 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
905 * low bits so that an underflow or overflow of page_mapcount() won't be
906 * mistaken for a page type value.
909 #define PAGE_TYPE_BASE 0xf0000000
910 /* Reserve 0x0000007f to catch underflows of page_mapcount */
911 #define PAGE_MAPCOUNT_RESERVE -128
912 #define PG_buddy 0x00000080
913 #define PG_offline 0x00000100
914 #define PG_table 0x00000200
915 #define PG_guard 0x00000400
917 #define PageType(page, flag) \
918 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
920 static inline int page_has_type(struct page *page)
922 return (int)page->page_type < PAGE_MAPCOUNT_RESERVE;
925 #define PAGE_TYPE_OPS(uname, lname) \
926 static __always_inline int Page##uname(struct page *page) \
928 return PageType(page, PG_##lname); \
930 static __always_inline void __SetPage##uname(struct page *page) \
932 VM_BUG_ON_PAGE(!PageType(page, 0), page); \
933 page->page_type &= ~PG_##lname; \
935 static __always_inline void __ClearPage##uname(struct page *page) \
937 VM_BUG_ON_PAGE(!Page##uname(page), page); \
938 page->page_type |= PG_##lname; \
942 * PageBuddy() indicates that the page is free and in the buddy system
943 * (see mm/page_alloc.c).
945 PAGE_TYPE_OPS(Buddy, buddy)
948 * PageOffline() indicates that the page is logically offline although the
949 * containing section is online. (e.g. inflated in a balloon driver or
950 * not onlined when onlining the section).
951 * The content of these pages is effectively stale. Such pages should not
952 * be touched (read/write/dump/save) except by their owner.
954 * If a driver wants to allow to offline unmovable PageOffline() pages without
955 * putting them back to the buddy, it can do so via the memory notifier by
956 * decrementing the reference count in MEM_GOING_OFFLINE and incrementing the
957 * reference count in MEM_CANCEL_OFFLINE. When offlining, the PageOffline()
958 * pages (now with a reference count of zero) are treated like free pages,
959 * allowing the containing memory block to get offlined. A driver that
960 * relies on this feature is aware that re-onlining the memory block will
961 * require to re-set the pages PageOffline() and not giving them to the
962 * buddy via online_page_callback_t.
964 * There are drivers that mark a page PageOffline() and expect there won't be
965 * any further access to page content. PFN walkers that read content of random
966 * pages should check PageOffline() and synchronize with such drivers using
967 * page_offline_freeze()/page_offline_thaw().
969 PAGE_TYPE_OPS(Offline, offline)
971 extern void page_offline_freeze(void);
972 extern void page_offline_thaw(void);
973 extern void page_offline_begin(void);
974 extern void page_offline_end(void);
977 * Marks pages in use as page tables.
979 PAGE_TYPE_OPS(Table, table)
982 * Marks guardpages used with debug_pagealloc.
984 PAGE_TYPE_OPS(Guard, guard)
986 extern bool is_free_buddy_page(struct page *page);
988 PAGEFLAG(Isolated, isolated, PF_ANY);
990 static __always_inline int PageAnonExclusive(struct page *page)
992 VM_BUG_ON_PGFLAGS(!PageAnon(page), page);
993 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
994 return test_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
997 static __always_inline void SetPageAnonExclusive(struct page *page)
999 VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
1000 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1001 set_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1004 static __always_inline void ClearPageAnonExclusive(struct page *page)
1006 VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
1007 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1008 clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1011 static __always_inline void __ClearPageAnonExclusive(struct page *page)
1013 VM_BUG_ON_PGFLAGS(!PageAnon(page), page);
1014 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1015 __clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1019 #define __PG_MLOCKED (1UL << PG_mlocked)
1021 #define __PG_MLOCKED 0
1025 * Flags checked when a page is freed. Pages being freed should not have
1026 * these flags set. If they are, there is a problem.
1028 #define PAGE_FLAGS_CHECK_AT_FREE \
1029 (1UL << PG_lru | 1UL << PG_locked | \
1030 1UL << PG_private | 1UL << PG_private_2 | \
1031 1UL << PG_writeback | 1UL << PG_reserved | \
1032 1UL << PG_slab | 1UL << PG_active | \
1033 1UL << PG_unevictable | __PG_MLOCKED | LRU_GEN_MASK)
1036 * Flags checked when a page is prepped for return by the page allocator.
1037 * Pages being prepped should not have these flags set. If they are set,
1038 * there has been a kernel bug or struct page corruption.
1040 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
1041 * alloc-free cycle to prevent from reusing the page.
1043 #define PAGE_FLAGS_CHECK_AT_PREP \
1044 ((PAGEFLAGS_MASK & ~__PG_HWPOISON) | LRU_GEN_MASK | LRU_REFS_MASK)
1046 #define PAGE_FLAGS_PRIVATE \
1047 (1UL << PG_private | 1UL << PG_private_2)
1049 * page_has_private - Determine if page has private stuff
1050 * @page: The page to be checked
1052 * Determine if a page has private stuff, indicating that release routines
1053 * should be invoked upon it.
1055 static inline int page_has_private(struct page *page)
1057 return !!(page->flags & PAGE_FLAGS_PRIVATE);
1060 static inline bool folio_has_private(struct folio *folio)
1062 return page_has_private(&folio->page);
1069 #undef PF_NO_COMPOUND
1071 #endif /* !__GENERATING_BOUNDS_H */
1073 #endif /* PAGE_FLAGS_H */