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)
138 #ifdef CONFIG_KASAN_HW_TAGS
139 PG_skip_kasan_poison,
143 PG_readahead = PG_reclaim,
146 PG_checked = PG_owner_priv_1,
149 PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */
151 /* Two page bits are conscripted by FS-Cache to maintain local caching
152 * state. These bits are set on pages belonging to the netfs's inodes
153 * when those inodes are being locally cached.
155 PG_fscache = PG_private_2, /* page backed by cache */
158 /* Pinned in Xen as a read-only pagetable page. */
159 PG_pinned = PG_owner_priv_1,
160 /* Pinned as part of domain save (see xen_mm_pin_all()). */
161 PG_savepinned = PG_dirty,
162 /* Has a grant mapping of another (foreign) domain's page. */
163 PG_foreign = PG_owner_priv_1,
164 /* Remapped by swiotlb-xen. */
165 PG_xen_remapped = PG_owner_priv_1,
168 PG_slob_free = PG_private,
170 /* Compound pages. Stored in first tail page's flags */
171 PG_double_map = PG_workingset,
173 #ifdef CONFIG_MEMORY_FAILURE
175 * Compound pages. Stored in first tail page's flags.
176 * Indicates that at least one subpage is hwpoisoned in the
179 PG_has_hwpoisoned = PG_mappedtodisk,
182 /* non-lru isolated movable page */
183 PG_isolated = PG_reclaim,
185 /* Only valid for buddy pages. Used to track pages that are reported */
186 PG_reported = PG_uptodate,
189 #define PAGEFLAGS_MASK ((1UL << NR_PAGEFLAGS) - 1)
191 #ifndef __GENERATING_BOUNDS_H
193 static inline unsigned long _compound_head(const struct page *page)
195 unsigned long head = READ_ONCE(page->compound_head);
197 if (unlikely(head & 1))
199 return (unsigned long)page;
202 #define compound_head(page) ((typeof(page))_compound_head(page))
205 * page_folio - Converts from page to folio.
208 * Every page is part of a folio. This function cannot be called on a
211 * Context: No reference, nor lock is required on @page. If the caller
212 * does not hold a reference, this call may race with a folio split, so
213 * it should re-check the folio still contains this page after gaining
214 * a reference on the folio.
215 * Return: The folio which contains this page.
217 #define page_folio(p) (_Generic((p), \
218 const struct page *: (const struct folio *)_compound_head(p), \
219 struct page *: (struct folio *)_compound_head(p)))
222 * folio_page - Return a page from a folio.
224 * @n: The page number to return.
226 * @n is relative to the start of the folio. This function does not
227 * check that the page number lies within @folio; the caller is presumed
228 * to have a reference to the page.
230 #define folio_page(folio, n) nth_page(&(folio)->page, n)
232 static __always_inline int PageTail(struct page *page)
234 return READ_ONCE(page->compound_head) & 1;
237 static __always_inline int PageCompound(struct page *page)
239 return test_bit(PG_head, &page->flags) || PageTail(page);
242 #define PAGE_POISON_PATTERN -1l
243 static inline int PagePoisoned(const struct page *page)
245 return READ_ONCE(page->flags) == PAGE_POISON_PATTERN;
248 #ifdef CONFIG_DEBUG_VM
249 void page_init_poison(struct page *page, size_t size);
251 static inline void page_init_poison(struct page *page, size_t size)
256 static unsigned long *folio_flags(struct folio *folio, unsigned n)
258 struct page *page = &folio->page;
260 VM_BUG_ON_PGFLAGS(PageTail(page), page);
261 VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags), page);
262 return &page[n].flags;
266 * Page flags policies wrt compound pages
269 * check if this struct page poisoned/uninitialized
272 * the page flag is relevant for small, head and tail pages.
275 * for compound page all operations related to the page flag applied to
279 * for compound page, callers only ever operate on the head page.
282 * modifications of the page flag must be done on small or head pages,
283 * checks can be done on tail pages too.
286 * the page flag is not relevant for compound pages.
289 * the page flag is stored in the first tail page.
291 #define PF_POISONED_CHECK(page) ({ \
292 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \
294 #define PF_ANY(page, enforce) PF_POISONED_CHECK(page)
295 #define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page))
296 #define PF_ONLY_HEAD(page, enforce) ({ \
297 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
298 PF_POISONED_CHECK(page); })
299 #define PF_NO_TAIL(page, enforce) ({ \
300 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
301 PF_POISONED_CHECK(compound_head(page)); })
302 #define PF_NO_COMPOUND(page, enforce) ({ \
303 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
304 PF_POISONED_CHECK(page); })
305 #define PF_SECOND(page, enforce) ({ \
306 VM_BUG_ON_PGFLAGS(!PageHead(page), page); \
307 PF_POISONED_CHECK(&page[1]); })
309 /* Which page is the flag stored in */
310 #define FOLIO_PF_ANY 0
311 #define FOLIO_PF_HEAD 0
312 #define FOLIO_PF_ONLY_HEAD 0
313 #define FOLIO_PF_NO_TAIL 0
314 #define FOLIO_PF_NO_COMPOUND 0
315 #define FOLIO_PF_SECOND 1
318 * Macros to create function definitions for page flags
320 #define TESTPAGEFLAG(uname, lname, policy) \
321 static __always_inline bool folio_test_##lname(struct folio *folio) \
322 { return test_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
323 static __always_inline int Page##uname(struct page *page) \
324 { return test_bit(PG_##lname, &policy(page, 0)->flags); }
326 #define SETPAGEFLAG(uname, lname, policy) \
327 static __always_inline \
328 void folio_set_##lname(struct folio *folio) \
329 { set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
330 static __always_inline void SetPage##uname(struct page *page) \
331 { set_bit(PG_##lname, &policy(page, 1)->flags); }
333 #define CLEARPAGEFLAG(uname, lname, policy) \
334 static __always_inline \
335 void folio_clear_##lname(struct folio *folio) \
336 { clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
337 static __always_inline void ClearPage##uname(struct page *page) \
338 { clear_bit(PG_##lname, &policy(page, 1)->flags); }
340 #define __SETPAGEFLAG(uname, lname, policy) \
341 static __always_inline \
342 void __folio_set_##lname(struct folio *folio) \
343 { __set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
344 static __always_inline void __SetPage##uname(struct page *page) \
345 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
347 #define __CLEARPAGEFLAG(uname, lname, policy) \
348 static __always_inline \
349 void __folio_clear_##lname(struct folio *folio) \
350 { __clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
351 static __always_inline void __ClearPage##uname(struct page *page) \
352 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
354 #define TESTSETFLAG(uname, lname, policy) \
355 static __always_inline \
356 bool folio_test_set_##lname(struct folio *folio) \
357 { return test_and_set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
358 static __always_inline int TestSetPage##uname(struct page *page) \
359 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
361 #define TESTCLEARFLAG(uname, lname, policy) \
362 static __always_inline \
363 bool folio_test_clear_##lname(struct folio *folio) \
364 { return test_and_clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
365 static __always_inline int TestClearPage##uname(struct page *page) \
366 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
368 #define PAGEFLAG(uname, lname, policy) \
369 TESTPAGEFLAG(uname, lname, policy) \
370 SETPAGEFLAG(uname, lname, policy) \
371 CLEARPAGEFLAG(uname, lname, policy)
373 #define __PAGEFLAG(uname, lname, policy) \
374 TESTPAGEFLAG(uname, lname, policy) \
375 __SETPAGEFLAG(uname, lname, policy) \
376 __CLEARPAGEFLAG(uname, lname, policy)
378 #define TESTSCFLAG(uname, lname, policy) \
379 TESTSETFLAG(uname, lname, policy) \
380 TESTCLEARFLAG(uname, lname, policy)
382 #define TESTPAGEFLAG_FALSE(uname, lname) \
383 static inline bool folio_test_##lname(const struct folio *folio) { return false; } \
384 static inline int Page##uname(const struct page *page) { return 0; }
386 #define SETPAGEFLAG_NOOP(uname, lname) \
387 static inline void folio_set_##lname(struct folio *folio) { } \
388 static inline void SetPage##uname(struct page *page) { }
390 #define CLEARPAGEFLAG_NOOP(uname, lname) \
391 static inline void folio_clear_##lname(struct folio *folio) { } \
392 static inline void ClearPage##uname(struct page *page) { }
394 #define __CLEARPAGEFLAG_NOOP(uname, lname) \
395 static inline void __folio_clear_##lname(struct folio *folio) { } \
396 static inline void __ClearPage##uname(struct page *page) { }
398 #define TESTSETFLAG_FALSE(uname, lname) \
399 static inline bool folio_test_set_##lname(struct folio *folio) \
401 static inline int TestSetPage##uname(struct page *page) { return 0; }
403 #define TESTCLEARFLAG_FALSE(uname, lname) \
404 static inline bool folio_test_clear_##lname(struct folio *folio) \
406 static inline int TestClearPage##uname(struct page *page) { return 0; }
408 #define PAGEFLAG_FALSE(uname, lname) TESTPAGEFLAG_FALSE(uname, lname) \
409 SETPAGEFLAG_NOOP(uname, lname) CLEARPAGEFLAG_NOOP(uname, lname)
411 #define TESTSCFLAG_FALSE(uname, lname) \
412 TESTSETFLAG_FALSE(uname, lname) TESTCLEARFLAG_FALSE(uname, lname)
414 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
415 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
416 PAGEFLAG(Error, error, PF_NO_TAIL) TESTCLEARFLAG(Error, error, PF_NO_TAIL)
417 PAGEFLAG(Referenced, referenced, PF_HEAD)
418 TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
419 __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
420 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
421 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
422 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
423 TESTCLEARFLAG(LRU, lru, PF_HEAD)
424 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
425 TESTCLEARFLAG(Active, active, PF_HEAD)
426 PAGEFLAG(Workingset, workingset, PF_HEAD)
427 TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
428 __PAGEFLAG(Slab, slab, PF_NO_TAIL)
429 __PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
430 PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
433 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
434 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
435 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
436 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
437 PAGEFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
438 TESTCLEARFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
440 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
441 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
442 __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
443 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
444 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
445 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
448 * Private page markings that may be used by the filesystem that owns the page
449 * for its own purposes.
450 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
452 PAGEFLAG(Private, private, PF_ANY)
453 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
454 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
455 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
458 * Only test-and-set exist for PG_writeback. The unconditional operators are
459 * risky: they bypass page accounting.
461 TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL)
462 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)
463 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
465 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
466 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
467 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
468 PAGEFLAG(Readahead, readahead, PF_NO_COMPOUND)
469 TESTCLEARFLAG(Readahead, readahead, PF_NO_COMPOUND)
471 #ifdef CONFIG_HIGHMEM
473 * Must use a macro here due to header dependency issues. page_zone() is not
474 * available at this point.
476 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
478 PAGEFLAG_FALSE(HighMem, highmem)
482 static __always_inline bool folio_test_swapcache(struct folio *folio)
484 return folio_test_swapbacked(folio) &&
485 test_bit(PG_swapcache, folio_flags(folio, 0));
488 static __always_inline bool PageSwapCache(struct page *page)
490 return folio_test_swapcache(page_folio(page));
493 SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
494 CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
496 PAGEFLAG_FALSE(SwapCache, swapcache)
499 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
500 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
501 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
504 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
505 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
506 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
508 PAGEFLAG_FALSE(Mlocked, mlocked) __CLEARPAGEFLAG_NOOP(Mlocked, mlocked)
509 TESTSCFLAG_FALSE(Mlocked, mlocked)
512 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
513 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
515 PAGEFLAG_FALSE(Uncached, uncached)
518 #ifdef CONFIG_MEMORY_FAILURE
519 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
520 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
521 #define __PG_HWPOISON (1UL << PG_hwpoison)
522 #define MAGIC_HWPOISON 0x48575053U /* HWPS */
523 extern void SetPageHWPoisonTakenOff(struct page *page);
524 extern void ClearPageHWPoisonTakenOff(struct page *page);
525 extern bool take_page_off_buddy(struct page *page);
526 extern bool put_page_back_buddy(struct page *page);
528 PAGEFLAG_FALSE(HWPoison, hwpoison)
529 #define __PG_HWPOISON 0
532 #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
533 TESTPAGEFLAG(Young, young, PF_ANY)
534 SETPAGEFLAG(Young, young, PF_ANY)
535 TESTCLEARFLAG(Young, young, PF_ANY)
536 PAGEFLAG(Idle, idle, PF_ANY)
539 #ifdef CONFIG_KASAN_HW_TAGS
540 PAGEFLAG(SkipKASanPoison, skip_kasan_poison, PF_HEAD)
542 PAGEFLAG_FALSE(SkipKASanPoison, skip_kasan_poison)
546 * PageReported() is used to track reported free pages within the Buddy
547 * allocator. We can use the non-atomic version of the test and set
548 * operations as both should be shielded with the zone lock to prevent
549 * any possible races on the setting or clearing of the bit.
551 __PAGEFLAG(Reported, reported, PF_NO_COMPOUND)
554 * On an anonymous page mapped into a user virtual memory area,
555 * page->mapping points to its anon_vma, not to a struct address_space;
556 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
558 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
559 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
560 * bit; and then page->mapping points, not to an anon_vma, but to a private
561 * structure which KSM associates with that merged page. See ksm.h.
563 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
564 * page and then page->mapping points a struct address_space.
566 * Please note that, confusingly, "page_mapping" refers to the inode
567 * address_space which maps the page from disk; whereas "page_mapped"
568 * refers to user virtual address space into which the page is mapped.
570 #define PAGE_MAPPING_ANON 0x1
571 #define PAGE_MAPPING_MOVABLE 0x2
572 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
573 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
575 static __always_inline int PageMappingFlags(struct page *page)
577 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
580 static __always_inline bool folio_test_anon(struct folio *folio)
582 return ((unsigned long)folio->mapping & PAGE_MAPPING_ANON) != 0;
585 static __always_inline bool PageAnon(struct page *page)
587 return folio_test_anon(page_folio(page));
590 static __always_inline int __PageMovable(struct page *page)
592 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
593 PAGE_MAPPING_MOVABLE;
598 * A KSM page is one of those write-protected "shared pages" or "merged pages"
599 * which KSM maps into multiple mms, wherever identical anonymous page content
600 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
601 * anon_vma, but to that page's node of the stable tree.
603 static __always_inline bool folio_test_ksm(struct folio *folio)
605 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
609 static __always_inline bool PageKsm(struct page *page)
611 return folio_test_ksm(page_folio(page));
614 TESTPAGEFLAG_FALSE(Ksm, ksm)
617 u64 stable_page_flags(struct page *page);
620 * folio_test_uptodate - Is this folio up to date?
623 * The uptodate flag is set on a folio when every byte in the folio is
624 * at least as new as the corresponding bytes on storage. Anonymous
625 * and CoW folios are always uptodate. If the folio is not uptodate,
626 * some of the bytes in it may be; see the is_partially_uptodate()
627 * address_space operation.
629 static inline bool folio_test_uptodate(struct folio *folio)
631 bool ret = test_bit(PG_uptodate, folio_flags(folio, 0));
633 * Must ensure that the data we read out of the folio is loaded
634 * _after_ we've loaded folio->flags to check the uptodate bit.
635 * We can skip the barrier if the folio is not uptodate, because
636 * we wouldn't be reading anything from it.
638 * See folio_mark_uptodate() for the other side of the story.
646 static inline int PageUptodate(struct page *page)
648 return folio_test_uptodate(page_folio(page));
651 static __always_inline void __folio_mark_uptodate(struct folio *folio)
654 __set_bit(PG_uptodate, folio_flags(folio, 0));
657 static __always_inline void folio_mark_uptodate(struct folio *folio)
660 * Memory barrier must be issued before setting the PG_uptodate bit,
661 * so that all previous stores issued in order to bring the folio
662 * uptodate are actually visible before folio_test_uptodate becomes true.
665 set_bit(PG_uptodate, folio_flags(folio, 0));
668 static __always_inline void __SetPageUptodate(struct page *page)
670 __folio_mark_uptodate((struct folio *)page);
673 static __always_inline void SetPageUptodate(struct page *page)
675 folio_mark_uptodate((struct folio *)page);
678 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
680 bool __folio_start_writeback(struct folio *folio, bool keep_write);
681 bool set_page_writeback(struct page *page);
683 #define folio_start_writeback(folio) \
684 __folio_start_writeback(folio, false)
685 #define folio_start_writeback_keepwrite(folio) \
686 __folio_start_writeback(folio, true)
688 static inline void set_page_writeback_keepwrite(struct page *page)
690 folio_start_writeback_keepwrite(page_folio(page));
693 static inline bool test_set_page_writeback(struct page *page)
695 return set_page_writeback(page);
698 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
701 * folio_test_large() - Does this folio contain more than one page?
702 * @folio: The folio to test.
704 * Return: True if the folio is larger than one page.
706 static inline bool folio_test_large(struct folio *folio)
708 return folio_test_head(folio);
711 static __always_inline void set_compound_head(struct page *page, struct page *head)
713 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
716 static __always_inline void clear_compound_head(struct page *page)
718 WRITE_ONCE(page->compound_head, 0);
721 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
722 static inline void ClearPageCompound(struct page *page)
724 BUG_ON(!PageHead(page));
729 #define PG_head_mask ((1UL << PG_head))
731 #ifdef CONFIG_HUGETLB_PAGE
732 int PageHuge(struct page *page);
733 int PageHeadHuge(struct page *page);
734 static inline bool folio_test_hugetlb(struct folio *folio)
736 return PageHeadHuge(&folio->page);
739 TESTPAGEFLAG_FALSE(Huge, hugetlb)
740 TESTPAGEFLAG_FALSE(HeadHuge, headhuge)
743 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
745 * PageHuge() only returns true for hugetlbfs pages, but not for
746 * normal or transparent huge pages.
748 * PageTransHuge() returns true for both transparent huge and
749 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
750 * called only in the core VM paths where hugetlbfs pages can't exist.
752 static inline int PageTransHuge(struct page *page)
754 VM_BUG_ON_PAGE(PageTail(page), page);
755 return PageHead(page);
758 static inline bool folio_test_transhuge(struct folio *folio)
760 return folio_test_head(folio);
764 * PageTransCompound returns true for both transparent huge pages
765 * and hugetlbfs pages, so it should only be called when it's known
766 * that hugetlbfs pages aren't involved.
768 static inline int PageTransCompound(struct page *page)
770 return PageCompound(page);
774 * PageTransTail returns true for both transparent huge pages
775 * and hugetlbfs pages, so it should only be called when it's known
776 * that hugetlbfs pages aren't involved.
778 static inline int PageTransTail(struct page *page)
780 return PageTail(page);
784 * PageDoubleMap indicates that the compound page is mapped with PTEs as well
787 * This is required for optimization of rmap operations for THP: we can postpone
788 * per small page mapcount accounting (and its overhead from atomic operations)
789 * until the first PMD split.
791 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
792 * by one. This reference will go away with last compound_mapcount.
794 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
796 PAGEFLAG(DoubleMap, double_map, PF_SECOND)
797 TESTSCFLAG(DoubleMap, double_map, PF_SECOND)
799 TESTPAGEFLAG_FALSE(TransHuge, transhuge)
800 TESTPAGEFLAG_FALSE(TransCompound, transcompound)
801 TESTPAGEFLAG_FALSE(TransCompoundMap, transcompoundmap)
802 TESTPAGEFLAG_FALSE(TransTail, transtail)
803 PAGEFLAG_FALSE(DoubleMap, double_map)
804 TESTSCFLAG_FALSE(DoubleMap, double_map)
807 #if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
809 * PageHasHWPoisoned indicates that at least one subpage is hwpoisoned in the
812 * This flag is set by hwpoison handler. Cleared by THP split or free page.
814 PAGEFLAG(HasHWPoisoned, has_hwpoisoned, PF_SECOND)
815 TESTSCFLAG(HasHWPoisoned, has_hwpoisoned, PF_SECOND)
817 PAGEFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
818 TESTSCFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
822 * Check if a page is currently marked HWPoisoned. Note that this check is
823 * best effort only and inherently racy: there is no way to synchronize with
826 static inline bool is_page_hwpoison(struct page *page)
828 if (PageHWPoison(page))
830 return PageHuge(page) && PageHWPoison(compound_head(page));
834 * For pages that are never mapped to userspace (and aren't PageSlab),
835 * page_type may be used. Because it is initialised to -1, we invert the
836 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
837 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
838 * low bits so that an underflow or overflow of page_mapcount() won't be
839 * mistaken for a page type value.
842 #define PAGE_TYPE_BASE 0xf0000000
843 /* Reserve 0x0000007f to catch underflows of page_mapcount */
844 #define PAGE_MAPCOUNT_RESERVE -128
845 #define PG_buddy 0x00000080
846 #define PG_offline 0x00000100
847 #define PG_table 0x00000200
848 #define PG_guard 0x00000400
850 #define PageType(page, flag) \
851 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
853 static inline int page_has_type(struct page *page)
855 return (int)page->page_type < PAGE_MAPCOUNT_RESERVE;
858 #define PAGE_TYPE_OPS(uname, lname) \
859 static __always_inline int Page##uname(struct page *page) \
861 return PageType(page, PG_##lname); \
863 static __always_inline void __SetPage##uname(struct page *page) \
865 VM_BUG_ON_PAGE(!PageType(page, 0), page); \
866 page->page_type &= ~PG_##lname; \
868 static __always_inline void __ClearPage##uname(struct page *page) \
870 VM_BUG_ON_PAGE(!Page##uname(page), page); \
871 page->page_type |= PG_##lname; \
875 * PageBuddy() indicates that the page is free and in the buddy system
876 * (see mm/page_alloc.c).
878 PAGE_TYPE_OPS(Buddy, buddy)
881 * PageOffline() indicates that the page is logically offline although the
882 * containing section is online. (e.g. inflated in a balloon driver or
883 * not onlined when onlining the section).
884 * The content of these pages is effectively stale. Such pages should not
885 * be touched (read/write/dump/save) except by their owner.
887 * If a driver wants to allow to offline unmovable PageOffline() pages without
888 * putting them back to the buddy, it can do so via the memory notifier by
889 * decrementing the reference count in MEM_GOING_OFFLINE and incrementing the
890 * reference count in MEM_CANCEL_OFFLINE. When offlining, the PageOffline()
891 * pages (now with a reference count of zero) are treated like free pages,
892 * allowing the containing memory block to get offlined. A driver that
893 * relies on this feature is aware that re-onlining the memory block will
894 * require to re-set the pages PageOffline() and not giving them to the
895 * buddy via online_page_callback_t.
897 * There are drivers that mark a page PageOffline() and expect there won't be
898 * any further access to page content. PFN walkers that read content of random
899 * pages should check PageOffline() and synchronize with such drivers using
900 * page_offline_freeze()/page_offline_thaw().
902 PAGE_TYPE_OPS(Offline, offline)
904 extern void page_offline_freeze(void);
905 extern void page_offline_thaw(void);
906 extern void page_offline_begin(void);
907 extern void page_offline_end(void);
910 * Marks pages in use as page tables.
912 PAGE_TYPE_OPS(Table, table)
915 * Marks guardpages used with debug_pagealloc.
917 PAGE_TYPE_OPS(Guard, guard)
919 extern bool is_free_buddy_page(struct page *page);
921 __PAGEFLAG(Isolated, isolated, PF_ANY);
924 * If network-based swap is enabled, sl*b must keep track of whether pages
925 * were allocated from pfmemalloc reserves.
927 static inline int PageSlabPfmemalloc(struct page *page)
929 VM_BUG_ON_PAGE(!PageSlab(page), page);
930 return PageActive(page);
934 * A version of PageSlabPfmemalloc() for opportunistic checks where the page
935 * might have been freed under us and not be a PageSlab anymore.
937 static inline int __PageSlabPfmemalloc(struct page *page)
939 return PageActive(page);
942 static inline void SetPageSlabPfmemalloc(struct page *page)
944 VM_BUG_ON_PAGE(!PageSlab(page), page);
948 static inline void __ClearPageSlabPfmemalloc(struct page *page)
950 VM_BUG_ON_PAGE(!PageSlab(page), page);
951 __ClearPageActive(page);
954 static inline void ClearPageSlabPfmemalloc(struct page *page)
956 VM_BUG_ON_PAGE(!PageSlab(page), page);
957 ClearPageActive(page);
961 #define __PG_MLOCKED (1UL << PG_mlocked)
963 #define __PG_MLOCKED 0
967 * Flags checked when a page is freed. Pages being freed should not have
968 * these flags set. If they are, there is a problem.
970 #define PAGE_FLAGS_CHECK_AT_FREE \
971 (1UL << PG_lru | 1UL << PG_locked | \
972 1UL << PG_private | 1UL << PG_private_2 | \
973 1UL << PG_writeback | 1UL << PG_reserved | \
974 1UL << PG_slab | 1UL << PG_active | \
975 1UL << PG_unevictable | __PG_MLOCKED)
978 * Flags checked when a page is prepped for return by the page allocator.
979 * Pages being prepped should not have these flags set. If they are set,
980 * there has been a kernel bug or struct page corruption.
982 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
983 * alloc-free cycle to prevent from reusing the page.
985 #define PAGE_FLAGS_CHECK_AT_PREP \
986 (PAGEFLAGS_MASK & ~__PG_HWPOISON)
988 #define PAGE_FLAGS_PRIVATE \
989 (1UL << PG_private | 1UL << PG_private_2)
991 * page_has_private - Determine if page has private stuff
992 * @page: The page to be checked
994 * Determine if a page has private stuff, indicating that release routines
995 * should be invoked upon it.
997 static inline int page_has_private(struct page *page)
999 return !!(page->flags & PAGE_FLAGS_PRIVATE);
1002 static inline bool folio_has_private(struct folio *folio)
1004 return page_has_private(&folio->page);
1011 #undef PF_NO_COMPOUND
1013 #endif /* !__GENERATING_BOUNDS_H */
1015 #endif /* PAGE_FLAGS_H */