1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Macros for manipulating and testing page->flags
4 */
5
6#ifndef PAGE_FLAGS_H
7#define PAGE_FLAGS_H
8
9#include <linux/types.h>
10#include <linux/bug.h>
11#include <linux/mmdebug.h>
12#ifndef __GENERATING_BOUNDS_H
13#include <linux/mm_types.h>
14#include <generated/bounds.h>
15#endif /* !__GENERATING_BOUNDS_H */
16
17/*
18 * Various page->flags bits:
19 *
20 * PG_reserved is set for special pages. The "struct page" of such a page
21 * should in general not be touched (e.g. set dirty) except by its owner.
22 * Pages marked as PG_reserved include:
23 * - Pages part of the kernel image (including vDSO) and similar (e.g. BIOS,
24 * initrd, HW tables)
25 * - Pages reserved or allocated early during boot (before the page allocator
26 * was initialized). This includes (depending on the architecture) the
27 * initial vmemmap, initial page tables, crashkernel, elfcorehdr, and much
28 * much more. Once (if ever) freed, PG_reserved is cleared and they will
29 * be given to the page allocator.
30 * - Pages falling into physical memory gaps - not IORESOURCE_SYSRAM. Trying
31 * to read/write these pages might end badly. Don't touch!
32 * - The zero page(s)
33 * - Pages not added to the page allocator when onlining a section because
34 * they were excluded via the online_page_callback() or because they are
35 * PG_hwpoison.
36 * - Pages allocated in the context of kexec/kdump (loaded kernel image,
37 * control pages, vmcoreinfo)
38 * - MMIO/DMA pages. Some architectures don't allow to ioremap pages that are
39 * not marked PG_reserved (as they might be in use by somebody else who does
40 * not respect the caching strategy).
41 * - Pages part of an offline section (struct pages of offline sections should
42 * not be trusted as they will be initialized when first onlined).
43 * - MCA pages on ia64
44 * - Pages holding CPU notes for POWER Firmware Assisted Dump
45 * - Device memory (e.g. PMEM, DAX, HMM)
46 * Some PG_reserved pages will be excluded from the hibernation image.
47 * PG_reserved does in general not hinder anybody from dumping or swapping
48 * and is no longer required for remap_pfn_range(). ioremap might require it.
49 * Consequently, PG_reserved for a page mapped into user space can indicate
50 * the zero page, the vDSO, MMIO pages or device memory.
51 *
52 * The PG_private bitflag is set on pagecache pages if they contain filesystem
53 * specific data (which is normally at page->private). It can be used by
54 * private allocations for its own usage.
55 *
56 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O
57 * and cleared when writeback _starts_ or when read _completes_. PG_writeback
58 * is set before writeback starts and cleared when it finishes.
59 *
60 * PG_locked also pins a page in pagecache, and blocks truncation of the file
61 * while it is held.
62 *
63 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
64 * to become unlocked.
65 *
66 * PG_uptodate tells whether the page's contents is valid. When a read
67 * completes, the page becomes uptodate, unless a disk I/O error happened.
68 *
69 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
70 * file-backed pagecache (see mm/vmscan.c).
71 *
72 * PG_error is set to indicate that an I/O error occurred on this page.
73 *
74 * PG_arch_1 is an architecture specific page state bit. The generic code
75 * guarantees that this bit is cleared for a page when it first is entered into
76 * the page cache.
77 *
78 * PG_hwpoison indicates that a page got corrupted in hardware and contains
79 * data with incorrect ECC bits that triggered a machine check. Accessing is
80 * not safe since it may cause another machine check. Don't touch!
81 */
82
83/*
84 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
85 * locked- and dirty-page accounting.
86 *
87 * The page flags field is split into two parts, the main flags area
88 * which extends from the low bits upwards, and the fields area which
89 * extends from the high bits downwards.
90 *
91 * | FIELD | ... | FLAGS |
92 * N-1 ^ 0
93 * (NR_PAGEFLAGS)
94 *
95 * The fields area is reserved for fields mapping zone, node (for NUMA) and
96 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like
97 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
98 */
99enum pageflags {
100 PG_locked, /* Page is locked. Don't touch. */
101 PG_referenced,
102 PG_uptodate,
103 PG_dirty,
104 PG_lru,
105 PG_active,
106 PG_workingset,
107 PG_waiters, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
108 PG_error,
109 PG_slab,
110 PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
111 PG_arch_1,
112 PG_reserved,
113 PG_private, /* If pagecache, has fs-private data */
114 PG_private_2, /* If pagecache, has fs aux data */
115 PG_writeback, /* Page is under writeback */
116 PG_head, /* A head page */
117 PG_mappedtodisk, /* Has blocks allocated on-disk */
118 PG_reclaim, /* To be reclaimed asap */
119 PG_swapbacked, /* Page is backed by RAM/swap */
120 PG_unevictable, /* Page is "unevictable" */
121#ifdef CONFIG_MMU
122 PG_mlocked, /* Page is vma mlocked */
123#endif
124#ifdef CONFIG_ARCH_USES_PG_UNCACHED
125 PG_uncached, /* Page has been mapped as uncached */
126#endif
127#ifdef CONFIG_MEMORY_FAILURE
128 PG_hwpoison, /* hardware poisoned page. Don't touch */
129#endif
130#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
131 PG_young,
132 PG_idle,
133#endif
134 __NR_PAGEFLAGS,
135
136 /* Filesystems */
137 PG_checked = PG_owner_priv_1,
138
139 /* SwapBacked */
140 PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */
141
142 /* Two page bits are conscripted by FS-Cache to maintain local caching
143 * state. These bits are set on pages belonging to the netfs's inodes
144 * when those inodes are being locally cached.
145 */
146 PG_fscache = PG_private_2, /* page backed by cache */
147
148 /* XEN */
149 /* Pinned in Xen as a read-only pagetable page. */
150 PG_pinned = PG_owner_priv_1,
151 /* Pinned as part of domain save (see xen_mm_pin_all()). */
152 PG_savepinned = PG_dirty,
153 /* Has a grant mapping of another (foreign) domain's page. */
154 PG_foreign = PG_owner_priv_1,
155
156 /* SLOB */
157 PG_slob_free = PG_private,
158
159 /* Compound pages. Stored in first tail page's flags */
160 PG_double_map = PG_private_2,
161
162 /* non-lru isolated movable page */
163 PG_isolated = PG_reclaim,
164};
165
166#ifndef __GENERATING_BOUNDS_H
167
168struct page; /* forward declaration */
169
170static inline struct page *compound_head(struct page *page)
171{
172 unsigned long head = READ_ONCE(page->compound_head);
173
174 if (unlikely(head & 1))
175 return (struct page *) (head - 1);
176 return page;
177}
178
179static __always_inline int PageTail(struct page *page)
180{
181 return READ_ONCE(page->compound_head) & 1;
182}
183
184static __always_inline int PageCompound(struct page *page)
185{
186 return test_bit(PG_head, &page->flags) || PageTail(page);
187}
188
189#define PAGE_POISON_PATTERN -1l
190static inline int PagePoisoned(const struct page *page)
191{
192 return page->flags == PAGE_POISON_PATTERN;
193}
194
195#ifdef CONFIG_DEBUG_VM
196void page_init_poison(struct page *page, size_t size);
197#else
198static inline void page_init_poison(struct page *page, size_t size)
199{
200}
201#endif
202
203/*
204 * Page flags policies wrt compound pages
205 *
206 * PF_POISONED_CHECK
207 * check if this struct page poisoned/uninitialized
208 *
209 * PF_ANY:
210 * the page flag is relevant for small, head and tail pages.
211 *
212 * PF_HEAD:
213 * for compound page all operations related to the page flag applied to
214 * head page.
215 *
216 * PF_ONLY_HEAD:
217 * for compound page, callers only ever operate on the head page.
218 *
219 * PF_NO_TAIL:
220 * modifications of the page flag must be done on small or head pages,
221 * checks can be done on tail pages too.
222 *
223 * PF_NO_COMPOUND:
224 * the page flag is not relevant for compound pages.
225 */
226#define PF_POISONED_CHECK(page) ({ \
227 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \
228 page; })
229#define PF_ANY(page, enforce) PF_POISONED_CHECK(page)
230#define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page))
231#define PF_ONLY_HEAD(page, enforce) ({ \
232 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
233 PF_POISONED_CHECK(page); })
234#define PF_NO_TAIL(page, enforce) ({ \
235 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
236 PF_POISONED_CHECK(compound_head(page)); })
237#define PF_NO_COMPOUND(page, enforce) ({ \
238 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
239 PF_POISONED_CHECK(page); })
240
241/*
242 * Macros to create function definitions for page flags
243 */
244#define TESTPAGEFLAG(uname, lname, policy) \
245static __always_inline int Page##uname(struct page *page) \
246 { return test_bit(PG_##lname, &policy(page, 0)->flags); }
247
248#define SETPAGEFLAG(uname, lname, policy) \
249static __always_inline void SetPage##uname(struct page *page) \
250 { set_bit(PG_##lname, &policy(page, 1)->flags); }
251
252#define CLEARPAGEFLAG(uname, lname, policy) \
253static __always_inline void ClearPage##uname(struct page *page) \
254 { clear_bit(PG_##lname, &policy(page, 1)->flags); }
255
256#define __SETPAGEFLAG(uname, lname, policy) \
257static __always_inline void __SetPage##uname(struct page *page) \
258 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
259
260#define __CLEARPAGEFLAG(uname, lname, policy) \
261static __always_inline void __ClearPage##uname(struct page *page) \
262 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
263
264#define TESTSETFLAG(uname, lname, policy) \
265static __always_inline int TestSetPage##uname(struct page *page) \
266 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
267
268#define TESTCLEARFLAG(uname, lname, policy) \
269static __always_inline int TestClearPage##uname(struct page *page) \
270 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
271
272#define PAGEFLAG(uname, lname, policy) \
273 TESTPAGEFLAG(uname, lname, policy) \
274 SETPAGEFLAG(uname, lname, policy) \
275 CLEARPAGEFLAG(uname, lname, policy)
276
277#define __PAGEFLAG(uname, lname, policy) \
278 TESTPAGEFLAG(uname, lname, policy) \
279 __SETPAGEFLAG(uname, lname, policy) \
280 __CLEARPAGEFLAG(uname, lname, policy)
281
282#define TESTSCFLAG(uname, lname, policy) \
283 TESTSETFLAG(uname, lname, policy) \
284 TESTCLEARFLAG(uname, lname, policy)
285
286#define TESTPAGEFLAG_FALSE(uname) \
287static inline int Page##uname(const struct page *page) { return 0; }
288
289#define SETPAGEFLAG_NOOP(uname) \
290static inline void SetPage##uname(struct page *page) { }
291
292#define CLEARPAGEFLAG_NOOP(uname) \
293static inline void ClearPage##uname(struct page *page) { }
294
295#define __CLEARPAGEFLAG_NOOP(uname) \
296static inline void __ClearPage##uname(struct page *page) { }
297
298#define TESTSETFLAG_FALSE(uname) \
299static inline int TestSetPage##uname(struct page *page) { return 0; }
300
301#define TESTCLEARFLAG_FALSE(uname) \
302static inline int TestClearPage##uname(struct page *page) { return 0; }
303
304#define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \
305 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
306
307#define TESTSCFLAG_FALSE(uname) \
308 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
309
310__PAGEFLAG(Locked, locked, PF_NO_TAIL)
311PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
312PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND)
313PAGEFLAG(Referenced, referenced, PF_HEAD)
314 TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
315 __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
316PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
317 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
318PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
319PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
320 TESTCLEARFLAG(Active, active, PF_HEAD)
321PAGEFLAG(Workingset, workingset, PF_HEAD)
322 TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
323__PAGEFLAG(Slab, slab, PF_NO_TAIL)
324__PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
325PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
326
327/* Xen */
328PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
329 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
330PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
331PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
332
333PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
334 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
335 __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
336PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
337 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
338 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
339
340/*
341 * Private page markings that may be used by the filesystem that owns the page
342 * for its own purposes.
343 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
344 */
345PAGEFLAG(Private, private, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY)
346 __CLEARPAGEFLAG(Private, private, PF_ANY)
347PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
348PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
349 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
350
351/*
352 * Only test-and-set exist for PG_writeback. The unconditional operators are
353 * risky: they bypass page accounting.
354 */
355TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL)
356 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)
357PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
358
359/* PG_readahead is only used for reads; PG_reclaim is only for writes */
360PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
361 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
362PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
363 TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
364
365#ifdef CONFIG_HIGHMEM
366/*
367 * Must use a macro here due to header dependency issues. page_zone() is not
368 * available at this point.
369 */
370#define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
371#else
372PAGEFLAG_FALSE(HighMem)
373#endif
374
375#ifdef CONFIG_SWAP
376static __always_inline int PageSwapCache(struct page *page)
377{
378#ifdef CONFIG_THP_SWAP
379 page = compound_head(page);
380#endif
381 return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags);
382
383}
384SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
385CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
386#else
387PAGEFLAG_FALSE(SwapCache)
388#endif
389
390PAGEFLAG(Unevictable, unevictable, PF_HEAD)
391 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
392 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
393
394#ifdef CONFIG_MMU
395PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
396 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
397 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
398#else
399PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
400 TESTSCFLAG_FALSE(Mlocked)
401#endif
402
403#ifdef CONFIG_ARCH_USES_PG_UNCACHED
404PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
405#else
406PAGEFLAG_FALSE(Uncached)
407#endif
408
409#ifdef CONFIG_MEMORY_FAILURE
410PAGEFLAG(HWPoison, hwpoison, PF_ANY)
411TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
412#define __PG_HWPOISON (1UL << PG_hwpoison)
413extern bool set_hwpoison_free_buddy_page(struct page *page);
414#else
415PAGEFLAG_FALSE(HWPoison)
416static inline bool set_hwpoison_free_buddy_page(struct page *page)
417{
418 return 0;
419}
420#define __PG_HWPOISON 0
421#endif
422
423#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
424TESTPAGEFLAG(Young, young, PF_ANY)
425SETPAGEFLAG(Young, young, PF_ANY)
426TESTCLEARFLAG(Young, young, PF_ANY)
427PAGEFLAG(Idle, idle, PF_ANY)
428#endif
429
430/*
431 * On an anonymous page mapped into a user virtual memory area,
432 * page->mapping points to its anon_vma, not to a struct address_space;
433 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
434 *
435 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
436 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
437 * bit; and then page->mapping points, not to an anon_vma, but to a private
438 * structure which KSM associates with that merged page. See ksm.h.
439 *
440 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
441 * page and then page->mapping points a struct address_space.
442 *
443 * Please note that, confusingly, "page_mapping" refers to the inode
444 * address_space which maps the page from disk; whereas "page_mapped"
445 * refers to user virtual address space into which the page is mapped.
446 */
447#define PAGE_MAPPING_ANON 0x1
448#define PAGE_MAPPING_MOVABLE 0x2
449#define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
450#define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
451
452static __always_inline int PageMappingFlags(struct page *page)
453{
454 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
455}
456
457static __always_inline int PageAnon(struct page *page)
458{
459 page = compound_head(page);
460 return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
461}
462
463static __always_inline int __PageMovable(struct page *page)
464{
465 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
466 PAGE_MAPPING_MOVABLE;
467}
468
469#ifdef CONFIG_KSM
470/*
471 * A KSM page is one of those write-protected "shared pages" or "merged pages"
472 * which KSM maps into multiple mms, wherever identical anonymous page content
473 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
474 * anon_vma, but to that page's node of the stable tree.
475 */
476static __always_inline int PageKsm(struct page *page)
477{
478 page = compound_head(page);
479 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
480 PAGE_MAPPING_KSM;
481}
482#else
483TESTPAGEFLAG_FALSE(Ksm)
484#endif
485
486u64 stable_page_flags(struct page *page);
487
488static inline int PageUptodate(struct page *page)
489{
490 int ret;
491 page = compound_head(page);
492 ret = test_bit(PG_uptodate, &(page)->flags);
493 /*
494 * Must ensure that the data we read out of the page is loaded
495 * _after_ we've loaded page->flags to check for PageUptodate.
496 * We can skip the barrier if the page is not uptodate, because
497 * we wouldn't be reading anything from it.
498 *
499 * See SetPageUptodate() for the other side of the story.
500 */
501 if (ret)
502 smp_rmb();
503
504 return ret;
505}
506
507static __always_inline void __SetPageUptodate(struct page *page)
508{
509 VM_BUG_ON_PAGE(PageTail(page), page);
510 smp_wmb();
511 __set_bit(PG_uptodate, &page->flags);
512}
513
514static __always_inline void SetPageUptodate(struct page *page)
515{
516 VM_BUG_ON_PAGE(PageTail(page), page);
517 /*
518 * Memory barrier must be issued before setting the PG_uptodate bit,
519 * so that all previous stores issued in order to bring the page
520 * uptodate are actually visible before PageUptodate becomes true.
521 */
522 smp_wmb();
523 set_bit(PG_uptodate, &page->flags);
524}
525
526CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
527
528int test_clear_page_writeback(struct page *page);
529int __test_set_page_writeback(struct page *page, bool keep_write);
530
531#define test_set_page_writeback(page) \
532 __test_set_page_writeback(page, false)
533#define test_set_page_writeback_keepwrite(page) \
534 __test_set_page_writeback(page, true)
535
536static inline void set_page_writeback(struct page *page)
537{
538 test_set_page_writeback(page);
539}
540
541static inline void set_page_writeback_keepwrite(struct page *page)
542{
543 test_set_page_writeback_keepwrite(page);
544}
545
546__PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
547
548static __always_inline void set_compound_head(struct page *page, struct page *head)
549{
550 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
551}
552
553static __always_inline void clear_compound_head(struct page *page)
554{
555 WRITE_ONCE(page->compound_head, 0);
556}
557
558#ifdef CONFIG_TRANSPARENT_HUGEPAGE
559static inline void ClearPageCompound(struct page *page)
560{
561 BUG_ON(!PageHead(page));
562 ClearPageHead(page);
563}
564#endif
565
566#define PG_head_mask ((1UL << PG_head))
567
568#ifdef CONFIG_HUGETLB_PAGE
569int PageHuge(struct page *page);
570int PageHeadHuge(struct page *page);
571bool page_huge_active(struct page *page);
572#else
573TESTPAGEFLAG_FALSE(Huge)
574TESTPAGEFLAG_FALSE(HeadHuge)
575
576static inline bool page_huge_active(struct page *page)
577{
578 return 0;
579}
580#endif
581
582
583#ifdef CONFIG_TRANSPARENT_HUGEPAGE
584/*
585 * PageHuge() only returns true for hugetlbfs pages, but not for
586 * normal or transparent huge pages.
587 *
588 * PageTransHuge() returns true for both transparent huge and
589 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
590 * called only in the core VM paths where hugetlbfs pages can't exist.
591 */
592static inline int PageTransHuge(struct page *page)
593{
594 VM_BUG_ON_PAGE(PageTail(page), page);
595 return PageHead(page);
596}
597
598/*
599 * PageTransCompound returns true for both transparent huge pages
600 * and hugetlbfs pages, so it should only be called when it's known
601 * that hugetlbfs pages aren't involved.
602 */
603static inline int PageTransCompound(struct page *page)
604{
605 return PageCompound(page);
606}
607
608/*
609 * PageTransCompoundMap is the same as PageTransCompound, but it also
610 * guarantees the primary MMU has the entire compound page mapped
611 * through pmd_trans_huge, which in turn guarantees the secondary MMUs
612 * can also map the entire compound page. This allows the secondary
613 * MMUs to call get_user_pages() only once for each compound page and
614 * to immediately map the entire compound page with a single secondary
615 * MMU fault. If there will be a pmd split later, the secondary MMUs
616 * will get an update through the MMU notifier invalidation through
617 * split_huge_pmd().
618 *
619 * Unlike PageTransCompound, this is safe to be called only while
620 * split_huge_pmd() cannot run from under us, like if protected by the
621 * MMU notifier, otherwise it may result in page->_mapcount < 0 false
622 * positives.
623 */
624static inline int PageTransCompoundMap(struct page *page)
625{
626 return PageTransCompound(page) && atomic_read(&page->_mapcount) < 0;
627}
628
629/*
630 * PageTransTail returns true for both transparent huge pages
631 * and hugetlbfs pages, so it should only be called when it's known
632 * that hugetlbfs pages aren't involved.
633 */
634static inline int PageTransTail(struct page *page)
635{
636 return PageTail(page);
637}
638
639/*
640 * PageDoubleMap indicates that the compound page is mapped with PTEs as well
641 * as PMDs.
642 *
643 * This is required for optimization of rmap operations for THP: we can postpone
644 * per small page mapcount accounting (and its overhead from atomic operations)
645 * until the first PMD split.
646 *
647 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
648 * by one. This reference will go away with last compound_mapcount.
649 *
650 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
651 */
652static inline int PageDoubleMap(struct page *page)
653{
654 return PageHead(page) && test_bit(PG_double_map, &page[1].flags);
655}
656
657static inline void SetPageDoubleMap(struct page *page)
658{
659 VM_BUG_ON_PAGE(!PageHead(page), page);
660 set_bit(PG_double_map, &page[1].flags);
661}
662
663static inline void ClearPageDoubleMap(struct page *page)
664{
665 VM_BUG_ON_PAGE(!PageHead(page), page);
666 clear_bit(PG_double_map, &page[1].flags);
667}
668static inline int TestSetPageDoubleMap(struct page *page)
669{
670 VM_BUG_ON_PAGE(!PageHead(page), page);
671 return test_and_set_bit(PG_double_map, &page[1].flags);
672}
673
674static inline int TestClearPageDoubleMap(struct page *page)
675{
676 VM_BUG_ON_PAGE(!PageHead(page), page);
677 return test_and_clear_bit(PG_double_map, &page[1].flags);
678}
679
680#else
681TESTPAGEFLAG_FALSE(TransHuge)
682TESTPAGEFLAG_FALSE(TransCompound)
683TESTPAGEFLAG_FALSE(TransCompoundMap)
684TESTPAGEFLAG_FALSE(TransTail)
685PAGEFLAG_FALSE(DoubleMap)
686 TESTSETFLAG_FALSE(DoubleMap)
687 TESTCLEARFLAG_FALSE(DoubleMap)
688#endif
689
690/*
691 * For pages that are never mapped to userspace (and aren't PageSlab),
692 * page_type may be used. Because it is initialised to -1, we invert the
693 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
694 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
695 * low bits so that an underflow or overflow of page_mapcount() won't be
696 * mistaken for a page type value.
697 */
698
699#define PAGE_TYPE_BASE 0xf0000000
700/* Reserve 0x0000007f to catch underflows of page_mapcount */
701#define PAGE_MAPCOUNT_RESERVE -128
702#define PG_buddy 0x00000080
703#define PG_offline 0x00000100
704#define PG_kmemcg 0x00000200
705#define PG_table 0x00000400
706
707#define PageType(page, flag) \
708 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
709
710static inline int page_has_type(struct page *page)
711{
712 return (int)page->page_type < PAGE_MAPCOUNT_RESERVE;
713}
714
715#define PAGE_TYPE_OPS(uname, lname) \
716static __always_inline int Page##uname(struct page *page) \
717{ \
718 return PageType(page, PG_##lname); \
719} \
720static __always_inline void __SetPage##uname(struct page *page) \
721{ \
722 VM_BUG_ON_PAGE(!PageType(page, 0), page); \
723 page->page_type &= ~PG_##lname; \
724} \
725static __always_inline void __ClearPage##uname(struct page *page) \
726{ \
727 VM_BUG_ON_PAGE(!Page##uname(page), page); \
728 page->page_type |= PG_##lname; \
729}
730
731/*
732 * PageBuddy() indicates that the page is free and in the buddy system
733 * (see mm/page_alloc.c).
734 */
735PAGE_TYPE_OPS(Buddy, buddy)
736
737/*
738 * PageOffline() indicates that the page is logically offline although the
739 * containing section is online. (e.g. inflated in a balloon driver or
740 * not onlined when onlining the section).
741 * The content of these pages is effectively stale. Such pages should not
742 * be touched (read/write/dump/save) except by their owner.
743 */
744PAGE_TYPE_OPS(Offline, offline)
745
746/*
747 * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on
748 * pages allocated with __GFP_ACCOUNT. It gets cleared on page free.
749 */
750PAGE_TYPE_OPS(Kmemcg, kmemcg)
751
752/*
753 * Marks pages in use as page tables.
754 */
755PAGE_TYPE_OPS(Table, table)
756
757extern bool is_free_buddy_page(struct page *page);
758
759__PAGEFLAG(Isolated, isolated, PF_ANY);
760
761/*
762 * If network-based swap is enabled, sl*b must keep track of whether pages
763 * were allocated from pfmemalloc reserves.
764 */
765static inline int PageSlabPfmemalloc(struct page *page)
766{
767 VM_BUG_ON_PAGE(!PageSlab(page), page);
768 return PageActive(page);
769}
770
771static inline void SetPageSlabPfmemalloc(struct page *page)
772{
773 VM_BUG_ON_PAGE(!PageSlab(page), page);
774 SetPageActive(page);
775}
776
777static inline void __ClearPageSlabPfmemalloc(struct page *page)
778{
779 VM_BUG_ON_PAGE(!PageSlab(page), page);
780 __ClearPageActive(page);
781}
782
783static inline void ClearPageSlabPfmemalloc(struct page *page)
784{
785 VM_BUG_ON_PAGE(!PageSlab(page), page);
786 ClearPageActive(page);
787}
788
789#ifdef CONFIG_MMU
790#define __PG_MLOCKED (1UL << PG_mlocked)
791#else
792#define __PG_MLOCKED 0
793#endif
794
795/*
796 * Flags checked when a page is freed. Pages being freed should not have
797 * these flags set. It they are, there is a problem.
798 */
799#define PAGE_FLAGS_CHECK_AT_FREE \
800 (1UL << PG_lru | 1UL << PG_locked | \
801 1UL << PG_private | 1UL << PG_private_2 | \
802 1UL << PG_writeback | 1UL << PG_reserved | \
803 1UL << PG_slab | 1UL << PG_active | \
804 1UL << PG_unevictable | __PG_MLOCKED)
805
806/*
807 * Flags checked when a page is prepped for return by the page allocator.
808 * Pages being prepped should not have these flags set. It they are set,
809 * there has been a kernel bug or struct page corruption.
810 *
811 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
812 * alloc-free cycle to prevent from reusing the page.
813 */
814#define PAGE_FLAGS_CHECK_AT_PREP \
815 (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
816
817#define PAGE_FLAGS_PRIVATE \
818 (1UL << PG_private | 1UL << PG_private_2)
819/**
820 * page_has_private - Determine if page has private stuff
821 * @page: The page to be checked
822 *
823 * Determine if a page has private stuff, indicating that release routines
824 * should be invoked upon it.
825 */
826static inline int page_has_private(struct page *page)
827{
828 return !!(page->flags & PAGE_FLAGS_PRIVATE);
829}
830
831#undef PF_ANY
832#undef PF_HEAD
833#undef PF_ONLY_HEAD
834#undef PF_NO_TAIL
835#undef PF_NO_COMPOUND
836#endif /* !__GENERATING_BOUNDS_H */
837
838#endif /* PAGE_FLAGS_H */
839