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