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,
178 PG_slob_free = PG_private,
180 #ifdef CONFIG_MEMORY_FAILURE
182 * Compound pages. Stored in first tail page's flags.
183 * Indicates that at least one subpage is hwpoisoned in the
186 PG_has_hwpoisoned = PG_error,
189 /* non-lru isolated movable page */
190 PG_isolated = PG_reclaim,
192 /* Only valid for buddy pages. Used to track pages that are reported */
193 PG_reported = PG_uptodate,
195 #ifdef CONFIG_MEMORY_HOTPLUG
196 /* For self-hosted memmap pages */
197 PG_vmemmap_self_hosted = PG_owner_priv_1,
201 #define PAGEFLAGS_MASK ((1UL << NR_PAGEFLAGS) - 1)
203 #ifndef __GENERATING_BOUNDS_H
205 #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
206 DECLARE_STATIC_KEY_FALSE(hugetlb_optimize_vmemmap_key);
209 * Return the real head page struct iff the @page is a fake head page, otherwise
210 * return the @page itself. See Documentation/mm/vmemmap_dedup.rst.
212 static __always_inline const struct page *page_fixed_fake_head(const struct page *page)
214 if (!static_branch_unlikely(&hugetlb_optimize_vmemmap_key))
218 * Only addresses aligned with PAGE_SIZE of struct page may be fake head
219 * struct page. The alignment check aims to avoid access the fields (
220 * e.g. compound_head) of the @page[1]. It can avoid touch a (possibly)
221 * cold cacheline in some cases.
223 if (IS_ALIGNED((unsigned long)page, PAGE_SIZE) &&
224 test_bit(PG_head, &page->flags)) {
226 * We can safely access the field of the @page[1] with PG_head
227 * because the @page is a compound page composed with at least
228 * two contiguous pages.
230 unsigned long head = READ_ONCE(page[1].compound_head);
232 if (likely(head & 1))
233 return (const struct page *)(head - 1);
238 static inline const struct page *page_fixed_fake_head(const struct page *page)
244 static __always_inline int page_is_fake_head(struct page *page)
246 return page_fixed_fake_head(page) != page;
249 static inline unsigned long _compound_head(const struct page *page)
251 unsigned long head = READ_ONCE(page->compound_head);
253 if (unlikely(head & 1))
255 return (unsigned long)page_fixed_fake_head(page);
258 #define compound_head(page) ((typeof(page))_compound_head(page))
261 * page_folio - Converts from page to folio.
264 * Every page is part of a folio. This function cannot be called on a
267 * Context: No reference, nor lock is required on @page. If the caller
268 * does not hold a reference, this call may race with a folio split, so
269 * it should re-check the folio still contains this page after gaining
270 * a reference on the folio.
271 * Return: The folio which contains this page.
273 #define page_folio(p) (_Generic((p), \
274 const struct page *: (const struct folio *)_compound_head(p), \
275 struct page *: (struct folio *)_compound_head(p)))
278 * folio_page - Return a page from a folio.
280 * @n: The page number to return.
282 * @n is relative to the start of the folio. This function does not
283 * check that the page number lies within @folio; the caller is presumed
284 * to have a reference to the page.
286 #define folio_page(folio, n) nth_page(&(folio)->page, n)
288 static __always_inline int PageTail(struct page *page)
290 return READ_ONCE(page->compound_head) & 1 || page_is_fake_head(page);
293 static __always_inline int PageCompound(struct page *page)
295 return test_bit(PG_head, &page->flags) ||
296 READ_ONCE(page->compound_head) & 1;
299 #define PAGE_POISON_PATTERN -1l
300 static inline int PagePoisoned(const struct page *page)
302 return READ_ONCE(page->flags) == PAGE_POISON_PATTERN;
305 #ifdef CONFIG_DEBUG_VM
306 void page_init_poison(struct page *page, size_t size);
308 static inline void page_init_poison(struct page *page, size_t size)
313 static unsigned long *folio_flags(struct folio *folio, unsigned n)
315 struct page *page = &folio->page;
317 VM_BUG_ON_PGFLAGS(PageTail(page), page);
318 VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags), page);
319 return &page[n].flags;
323 * Page flags policies wrt compound pages
326 * check if this struct page poisoned/uninitialized
329 * the page flag is relevant for small, head and tail pages.
332 * for compound page all operations related to the page flag applied to
336 * for compound page, callers only ever operate on the head page.
339 * modifications of the page flag must be done on small or head pages,
340 * checks can be done on tail pages too.
343 * the page flag is not relevant for compound pages.
346 * the page flag is stored in the first tail page.
348 #define PF_POISONED_CHECK(page) ({ \
349 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \
351 #define PF_ANY(page, enforce) PF_POISONED_CHECK(page)
352 #define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page))
353 #define PF_ONLY_HEAD(page, enforce) ({ \
354 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
355 PF_POISONED_CHECK(page); })
356 #define PF_NO_TAIL(page, enforce) ({ \
357 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
358 PF_POISONED_CHECK(compound_head(page)); })
359 #define PF_NO_COMPOUND(page, enforce) ({ \
360 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
361 PF_POISONED_CHECK(page); })
362 #define PF_SECOND(page, enforce) ({ \
363 VM_BUG_ON_PGFLAGS(!PageHead(page), page); \
364 PF_POISONED_CHECK(&page[1]); })
366 /* Which page is the flag stored in */
367 #define FOLIO_PF_ANY 0
368 #define FOLIO_PF_HEAD 0
369 #define FOLIO_PF_ONLY_HEAD 0
370 #define FOLIO_PF_NO_TAIL 0
371 #define FOLIO_PF_NO_COMPOUND 0
372 #define FOLIO_PF_SECOND 1
375 * Macros to create function definitions for page flags
377 #define TESTPAGEFLAG(uname, lname, policy) \
378 static __always_inline bool folio_test_##lname(struct folio *folio) \
379 { return test_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
380 static __always_inline int Page##uname(struct page *page) \
381 { return test_bit(PG_##lname, &policy(page, 0)->flags); }
383 #define SETPAGEFLAG(uname, lname, policy) \
384 static __always_inline \
385 void folio_set_##lname(struct folio *folio) \
386 { set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
387 static __always_inline void SetPage##uname(struct page *page) \
388 { set_bit(PG_##lname, &policy(page, 1)->flags); }
390 #define CLEARPAGEFLAG(uname, lname, policy) \
391 static __always_inline \
392 void folio_clear_##lname(struct folio *folio) \
393 { clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
394 static __always_inline void ClearPage##uname(struct page *page) \
395 { clear_bit(PG_##lname, &policy(page, 1)->flags); }
397 #define __SETPAGEFLAG(uname, lname, policy) \
398 static __always_inline \
399 void __folio_set_##lname(struct folio *folio) \
400 { __set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
401 static __always_inline void __SetPage##uname(struct page *page) \
402 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
404 #define __CLEARPAGEFLAG(uname, lname, policy) \
405 static __always_inline \
406 void __folio_clear_##lname(struct folio *folio) \
407 { __clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
408 static __always_inline void __ClearPage##uname(struct page *page) \
409 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
411 #define TESTSETFLAG(uname, lname, policy) \
412 static __always_inline \
413 bool folio_test_set_##lname(struct folio *folio) \
414 { return test_and_set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
415 static __always_inline int TestSetPage##uname(struct page *page) \
416 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
418 #define TESTCLEARFLAG(uname, lname, policy) \
419 static __always_inline \
420 bool folio_test_clear_##lname(struct folio *folio) \
421 { return test_and_clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
422 static __always_inline int TestClearPage##uname(struct page *page) \
423 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
425 #define PAGEFLAG(uname, lname, policy) \
426 TESTPAGEFLAG(uname, lname, policy) \
427 SETPAGEFLAG(uname, lname, policy) \
428 CLEARPAGEFLAG(uname, lname, policy)
430 #define __PAGEFLAG(uname, lname, policy) \
431 TESTPAGEFLAG(uname, lname, policy) \
432 __SETPAGEFLAG(uname, lname, policy) \
433 __CLEARPAGEFLAG(uname, lname, policy)
435 #define TESTSCFLAG(uname, lname, policy) \
436 TESTSETFLAG(uname, lname, policy) \
437 TESTCLEARFLAG(uname, lname, policy)
439 #define TESTPAGEFLAG_FALSE(uname, lname) \
440 static inline bool folio_test_##lname(const struct folio *folio) { return false; } \
441 static inline int Page##uname(const struct page *page) { return 0; }
443 #define SETPAGEFLAG_NOOP(uname, lname) \
444 static inline void folio_set_##lname(struct folio *folio) { } \
445 static inline void SetPage##uname(struct page *page) { }
447 #define CLEARPAGEFLAG_NOOP(uname, lname) \
448 static inline void folio_clear_##lname(struct folio *folio) { } \
449 static inline void ClearPage##uname(struct page *page) { }
451 #define __CLEARPAGEFLAG_NOOP(uname, lname) \
452 static inline void __folio_clear_##lname(struct folio *folio) { } \
453 static inline void __ClearPage##uname(struct page *page) { }
455 #define TESTSETFLAG_FALSE(uname, lname) \
456 static inline bool folio_test_set_##lname(struct folio *folio) \
458 static inline int TestSetPage##uname(struct page *page) { return 0; }
460 #define TESTCLEARFLAG_FALSE(uname, lname) \
461 static inline bool folio_test_clear_##lname(struct folio *folio) \
463 static inline int TestClearPage##uname(struct page *page) { return 0; }
465 #define PAGEFLAG_FALSE(uname, lname) TESTPAGEFLAG_FALSE(uname, lname) \
466 SETPAGEFLAG_NOOP(uname, lname) CLEARPAGEFLAG_NOOP(uname, lname)
468 #define TESTSCFLAG_FALSE(uname, lname) \
469 TESTSETFLAG_FALSE(uname, lname) TESTCLEARFLAG_FALSE(uname, lname)
471 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
472 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
473 PAGEFLAG(Error, error, PF_NO_TAIL) TESTCLEARFLAG(Error, error, PF_NO_TAIL)
474 PAGEFLAG(Referenced, referenced, PF_HEAD)
475 TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
476 __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
477 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
478 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
479 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
480 TESTCLEARFLAG(LRU, lru, PF_HEAD)
481 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
482 TESTCLEARFLAG(Active, active, PF_HEAD)
483 PAGEFLAG(Workingset, workingset, PF_HEAD)
484 TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
485 __PAGEFLAG(Slab, slab, PF_NO_TAIL)
486 __PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
487 PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
490 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
491 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
492 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
493 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
494 PAGEFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
495 TESTCLEARFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
497 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
498 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
499 __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
500 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
501 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
502 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
505 * Private page markings that may be used by the filesystem that owns the page
506 * for its own purposes.
507 * - PG_private and PG_private_2 cause release_folio() and co to be invoked
509 PAGEFLAG(Private, private, PF_ANY)
510 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
511 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
512 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
515 * Only test-and-set exist for PG_writeback. The unconditional operators are
516 * risky: they bypass page accounting.
518 TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL)
519 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)
520 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
522 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
523 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
524 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
525 PAGEFLAG(Readahead, readahead, PF_NO_COMPOUND)
526 TESTCLEARFLAG(Readahead, readahead, PF_NO_COMPOUND)
528 #ifdef CONFIG_HIGHMEM
530 * Must use a macro here due to header dependency issues. page_zone() is not
531 * available at this point.
533 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
534 #define folio_test_highmem(__f) is_highmem_idx(folio_zonenum(__f))
536 PAGEFLAG_FALSE(HighMem, highmem)
540 static __always_inline bool folio_test_swapcache(struct folio *folio)
542 return folio_test_swapbacked(folio) &&
543 test_bit(PG_swapcache, folio_flags(folio, 0));
546 static __always_inline bool PageSwapCache(struct page *page)
548 return folio_test_swapcache(page_folio(page));
551 SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
552 CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
554 PAGEFLAG_FALSE(SwapCache, swapcache)
557 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
558 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
559 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
562 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
563 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
564 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
566 PAGEFLAG_FALSE(Mlocked, mlocked) __CLEARPAGEFLAG_NOOP(Mlocked, mlocked)
567 TESTSCFLAG_FALSE(Mlocked, mlocked)
570 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
571 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
573 PAGEFLAG_FALSE(Uncached, uncached)
576 #ifdef CONFIG_MEMORY_FAILURE
577 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
578 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
579 #define __PG_HWPOISON (1UL << PG_hwpoison)
580 #define MAGIC_HWPOISON 0x48575053U /* HWPS */
581 extern void SetPageHWPoisonTakenOff(struct page *page);
582 extern void ClearPageHWPoisonTakenOff(struct page *page);
583 extern bool take_page_off_buddy(struct page *page);
584 extern bool put_page_back_buddy(struct page *page);
586 PAGEFLAG_FALSE(HWPoison, hwpoison)
587 #define __PG_HWPOISON 0
590 #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
591 TESTPAGEFLAG(Young, young, PF_ANY)
592 SETPAGEFLAG(Young, young, PF_ANY)
593 TESTCLEARFLAG(Young, young, PF_ANY)
594 PAGEFLAG(Idle, idle, PF_ANY)
597 #ifdef CONFIG_KASAN_HW_TAGS
598 PAGEFLAG(SkipKASanPoison, skip_kasan_poison, PF_HEAD)
600 PAGEFLAG_FALSE(SkipKASanPoison, skip_kasan_poison)
604 * PageReported() is used to track reported free pages within the Buddy
605 * allocator. We can use the non-atomic version of the test and set
606 * operations as both should be shielded with the zone lock to prevent
607 * any possible races on the setting or clearing of the bit.
609 __PAGEFLAG(Reported, reported, PF_NO_COMPOUND)
611 #ifdef CONFIG_MEMORY_HOTPLUG
612 PAGEFLAG(VmemmapSelfHosted, vmemmap_self_hosted, PF_ANY)
614 PAGEFLAG_FALSE(VmemmapSelfHosted, vmemmap_self_hosted)
618 * On an anonymous page mapped into a user virtual memory area,
619 * page->mapping points to its anon_vma, not to a struct address_space;
620 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
622 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
623 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
624 * bit; and then page->mapping points, not to an anon_vma, but to a private
625 * structure which KSM associates with that merged page. See ksm.h.
627 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
628 * page and then page->mapping points to a struct movable_operations.
630 * Please note that, confusingly, "page_mapping" refers to the inode
631 * address_space which maps the page from disk; whereas "page_mapped"
632 * refers to user virtual address space into which the page is mapped.
634 #define PAGE_MAPPING_ANON 0x1
635 #define PAGE_MAPPING_MOVABLE 0x2
636 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
637 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
640 * Different with flags above, this flag is used only for fsdax mode. It
641 * indicates that this page->mapping is now under reflink case.
643 #define PAGE_MAPPING_DAX_SHARED ((void *)0x1)
645 static __always_inline bool folio_mapping_flags(struct folio *folio)
647 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) != 0;
650 static __always_inline int PageMappingFlags(struct page *page)
652 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
655 static __always_inline bool folio_test_anon(struct folio *folio)
657 return ((unsigned long)folio->mapping & PAGE_MAPPING_ANON) != 0;
660 static __always_inline bool PageAnon(struct page *page)
662 return folio_test_anon(page_folio(page));
665 static __always_inline bool __folio_test_movable(const struct folio *folio)
667 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
668 PAGE_MAPPING_MOVABLE;
671 static __always_inline int __PageMovable(struct page *page)
673 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
674 PAGE_MAPPING_MOVABLE;
679 * A KSM page is one of those write-protected "shared pages" or "merged pages"
680 * which KSM maps into multiple mms, wherever identical anonymous page content
681 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
682 * anon_vma, but to that page's node of the stable tree.
684 static __always_inline bool folio_test_ksm(struct folio *folio)
686 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
690 static __always_inline bool PageKsm(struct page *page)
692 return folio_test_ksm(page_folio(page));
695 TESTPAGEFLAG_FALSE(Ksm, ksm)
698 u64 stable_page_flags(struct page *page);
701 * folio_test_uptodate - Is this folio up to date?
704 * The uptodate flag is set on a folio when every byte in the folio is
705 * at least as new as the corresponding bytes on storage. Anonymous
706 * and CoW folios are always uptodate. If the folio is not uptodate,
707 * some of the bytes in it may be; see the is_partially_uptodate()
708 * address_space operation.
710 static inline bool folio_test_uptodate(struct folio *folio)
712 bool ret = test_bit(PG_uptodate, folio_flags(folio, 0));
714 * Must ensure that the data we read out of the folio is loaded
715 * _after_ we've loaded folio->flags to check the uptodate bit.
716 * We can skip the barrier if the folio is not uptodate, because
717 * we wouldn't be reading anything from it.
719 * See folio_mark_uptodate() for the other side of the story.
727 static inline int PageUptodate(struct page *page)
729 return folio_test_uptodate(page_folio(page));
732 static __always_inline void __folio_mark_uptodate(struct folio *folio)
735 __set_bit(PG_uptodate, folio_flags(folio, 0));
738 static __always_inline void folio_mark_uptodate(struct folio *folio)
741 * Memory barrier must be issued before setting the PG_uptodate bit,
742 * so that all previous stores issued in order to bring the folio
743 * uptodate are actually visible before folio_test_uptodate becomes true.
746 set_bit(PG_uptodate, folio_flags(folio, 0));
749 static __always_inline void __SetPageUptodate(struct page *page)
751 __folio_mark_uptodate((struct folio *)page);
754 static __always_inline void SetPageUptodate(struct page *page)
756 folio_mark_uptodate((struct folio *)page);
759 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
761 bool __folio_start_writeback(struct folio *folio, bool keep_write);
762 bool set_page_writeback(struct page *page);
764 #define folio_start_writeback(folio) \
765 __folio_start_writeback(folio, false)
766 #define folio_start_writeback_keepwrite(folio) \
767 __folio_start_writeback(folio, true)
769 static inline void set_page_writeback_keepwrite(struct page *page)
771 folio_start_writeback_keepwrite(page_folio(page));
774 static inline bool test_set_page_writeback(struct page *page)
776 return set_page_writeback(page);
779 static __always_inline bool folio_test_head(struct folio *folio)
781 return test_bit(PG_head, folio_flags(folio, FOLIO_PF_ANY));
784 static __always_inline int PageHead(struct page *page)
786 PF_POISONED_CHECK(page);
787 return test_bit(PG_head, &page->flags) && !page_is_fake_head(page);
790 __SETPAGEFLAG(Head, head, PF_ANY)
791 __CLEARPAGEFLAG(Head, head, PF_ANY)
792 CLEARPAGEFLAG(Head, head, PF_ANY)
795 * folio_test_large() - Does this folio contain more than one page?
796 * @folio: The folio to test.
798 * Return: True if the folio is larger than one page.
800 static inline bool folio_test_large(struct folio *folio)
802 return folio_test_head(folio);
805 static __always_inline void set_compound_head(struct page *page, struct page *head)
807 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
810 static __always_inline void clear_compound_head(struct page *page)
812 WRITE_ONCE(page->compound_head, 0);
815 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
816 static inline void ClearPageCompound(struct page *page)
818 BUG_ON(!PageHead(page));
823 #define PG_head_mask ((1UL << PG_head))
825 #ifdef CONFIG_HUGETLB_PAGE
826 int PageHuge(struct page *page);
827 int PageHeadHuge(struct page *page);
828 static inline bool folio_test_hugetlb(struct folio *folio)
830 return PageHeadHuge(&folio->page);
833 TESTPAGEFLAG_FALSE(Huge, hugetlb)
834 TESTPAGEFLAG_FALSE(HeadHuge, headhuge)
837 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
839 * PageHuge() only returns true for hugetlbfs pages, but not for
840 * normal or transparent huge pages.
842 * PageTransHuge() returns true for both transparent huge and
843 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
844 * called only in the core VM paths where hugetlbfs pages can't exist.
846 static inline int PageTransHuge(struct page *page)
848 VM_BUG_ON_PAGE(PageTail(page), page);
849 return PageHead(page);
852 static inline bool folio_test_transhuge(struct folio *folio)
854 return folio_test_head(folio);
858 * PageTransCompound returns true for both transparent huge pages
859 * and hugetlbfs pages, so it should only be called when it's known
860 * that hugetlbfs pages aren't involved.
862 static inline int PageTransCompound(struct page *page)
864 return PageCompound(page);
868 * PageTransTail returns true for both transparent huge pages
869 * and hugetlbfs pages, so it should only be called when it's known
870 * that hugetlbfs pages aren't involved.
872 static inline int PageTransTail(struct page *page)
874 return PageTail(page);
877 TESTPAGEFLAG_FALSE(TransHuge, transhuge)
878 TESTPAGEFLAG_FALSE(TransCompound, transcompound)
879 TESTPAGEFLAG_FALSE(TransCompoundMap, transcompoundmap)
880 TESTPAGEFLAG_FALSE(TransTail, transtail)
883 #if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
885 * PageHasHWPoisoned indicates that at least one subpage is hwpoisoned in the
888 * This flag is set by hwpoison handler. Cleared by THP split or free page.
890 PAGEFLAG(HasHWPoisoned, has_hwpoisoned, PF_SECOND)
891 TESTSCFLAG(HasHWPoisoned, has_hwpoisoned, PF_SECOND)
893 PAGEFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
894 TESTSCFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
898 * Check if a page is currently marked HWPoisoned. Note that this check is
899 * best effort only and inherently racy: there is no way to synchronize with
902 static inline bool is_page_hwpoison(struct page *page)
904 if (PageHWPoison(page))
906 return PageHuge(page) && PageHWPoison(compound_head(page));
910 * For pages that are never mapped to userspace (and aren't PageSlab),
911 * page_type may be used. Because it is initialised to -1, we invert the
912 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
913 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
914 * low bits so that an underflow or overflow of page_mapcount() won't be
915 * mistaken for a page type value.
918 #define PAGE_TYPE_BASE 0xf0000000
919 /* Reserve 0x0000007f to catch underflows of page_mapcount */
920 #define PAGE_MAPCOUNT_RESERVE -128
921 #define PG_buddy 0x00000080
922 #define PG_offline 0x00000100
923 #define PG_table 0x00000200
924 #define PG_guard 0x00000400
926 #define PageType(page, flag) \
927 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
929 static inline int page_has_type(struct page *page)
931 return (int)page->page_type < PAGE_MAPCOUNT_RESERVE;
934 #define PAGE_TYPE_OPS(uname, lname) \
935 static __always_inline int Page##uname(struct page *page) \
937 return PageType(page, PG_##lname); \
939 static __always_inline void __SetPage##uname(struct page *page) \
941 VM_BUG_ON_PAGE(!PageType(page, 0), page); \
942 page->page_type &= ~PG_##lname; \
944 static __always_inline void __ClearPage##uname(struct page *page) \
946 VM_BUG_ON_PAGE(!Page##uname(page), page); \
947 page->page_type |= PG_##lname; \
951 * PageBuddy() indicates that the page is free and in the buddy system
952 * (see mm/page_alloc.c).
954 PAGE_TYPE_OPS(Buddy, buddy)
957 * PageOffline() indicates that the page is logically offline although the
958 * containing section is online. (e.g. inflated in a balloon driver or
959 * not onlined when onlining the section).
960 * The content of these pages is effectively stale. Such pages should not
961 * be touched (read/write/dump/save) except by their owner.
963 * If a driver wants to allow to offline unmovable PageOffline() pages without
964 * putting them back to the buddy, it can do so via the memory notifier by
965 * decrementing the reference count in MEM_GOING_OFFLINE and incrementing the
966 * reference count in MEM_CANCEL_OFFLINE. When offlining, the PageOffline()
967 * pages (now with a reference count of zero) are treated like free pages,
968 * allowing the containing memory block to get offlined. A driver that
969 * relies on this feature is aware that re-onlining the memory block will
970 * require to re-set the pages PageOffline() and not giving them to the
971 * buddy via online_page_callback_t.
973 * There are drivers that mark a page PageOffline() and expect there won't be
974 * any further access to page content. PFN walkers that read content of random
975 * pages should check PageOffline() and synchronize with such drivers using
976 * page_offline_freeze()/page_offline_thaw().
978 PAGE_TYPE_OPS(Offline, offline)
980 extern void page_offline_freeze(void);
981 extern void page_offline_thaw(void);
982 extern void page_offline_begin(void);
983 extern void page_offline_end(void);
986 * Marks pages in use as page tables.
988 PAGE_TYPE_OPS(Table, table)
991 * Marks guardpages used with debug_pagealloc.
993 PAGE_TYPE_OPS(Guard, guard)
995 extern bool is_free_buddy_page(struct page *page);
997 PAGEFLAG(Isolated, isolated, PF_ANY);
999 static __always_inline int PageAnonExclusive(struct page *page)
1001 VM_BUG_ON_PGFLAGS(!PageAnon(page), page);
1002 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1003 return test_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1006 static __always_inline void SetPageAnonExclusive(struct page *page)
1008 VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
1009 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1010 set_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1013 static __always_inline void ClearPageAnonExclusive(struct page *page)
1015 VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
1016 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1017 clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1020 static __always_inline void __ClearPageAnonExclusive(struct page *page)
1022 VM_BUG_ON_PGFLAGS(!PageAnon(page), page);
1023 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1024 __clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1028 #define __PG_MLOCKED (1UL << PG_mlocked)
1030 #define __PG_MLOCKED 0
1034 * Flags checked when a page is freed. Pages being freed should not have
1035 * these flags set. If they are, there is a problem.
1037 #define PAGE_FLAGS_CHECK_AT_FREE \
1038 (1UL << PG_lru | 1UL << PG_locked | \
1039 1UL << PG_private | 1UL << PG_private_2 | \
1040 1UL << PG_writeback | 1UL << PG_reserved | \
1041 1UL << PG_slab | 1UL << PG_active | \
1042 1UL << PG_unevictable | __PG_MLOCKED | LRU_GEN_MASK)
1045 * Flags checked when a page is prepped for return by the page allocator.
1046 * Pages being prepped should not have these flags set. If they are set,
1047 * there has been a kernel bug or struct page corruption.
1049 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
1050 * alloc-free cycle to prevent from reusing the page.
1052 #define PAGE_FLAGS_CHECK_AT_PREP \
1053 ((PAGEFLAGS_MASK & ~__PG_HWPOISON) | LRU_GEN_MASK | LRU_REFS_MASK)
1055 #define PAGE_FLAGS_PRIVATE \
1056 (1UL << PG_private | 1UL << PG_private_2)
1058 * page_has_private - Determine if page has private stuff
1059 * @page: The page to be checked
1061 * Determine if a page has private stuff, indicating that release routines
1062 * should be invoked upon it.
1064 static inline int page_has_private(struct page *page)
1066 return !!(page->flags & PAGE_FLAGS_PRIVATE);
1069 static inline bool folio_has_private(struct folio *folio)
1071 return page_has_private(&folio->page);
1078 #undef PF_NO_COMPOUND
1080 #endif /* !__GENERATING_BOUNDS_H */
1082 #endif /* PAGE_FLAGS_H */