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 */
70 enum 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
138 struct page; /* forward declaration */
139
compound_head(struct page * page)140 static 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
PageTail(struct page * page)149 static __always_inline int PageTail(struct page *page)
150 {
151 return READ_ONCE(page->compound_head) & 1;
152 }
153
PageCompound(struct page * page)154 static __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
PagePoisoned(const struct page * page)160 static 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) \
207 static __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) \
211 static __always_inline void SetPage##uname(struct page *page) \
212 { set_bit(PG_##lname, &policy(page, 1)->flags); }
213
214 #define CLEARPAGEFLAG(uname, lname, policy) \
215 static __always_inline void ClearPage##uname(struct page *page) \
216 { clear_bit(PG_##lname, &policy(page, 1)->flags); }
217
218 #define __SETPAGEFLAG(uname, lname, policy) \
219 static __always_inline void __SetPage##uname(struct page *page) \
220 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
221
222 #define __CLEARPAGEFLAG(uname, lname, policy) \
223 static __always_inline void __ClearPage##uname(struct page *page) \
224 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
225
226 #define TESTSETFLAG(uname, lname, policy) \
227 static __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) \
231 static __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) \
249 static inline int Page##uname(const struct page *page) { return 0; }
250
251 #define SETPAGEFLAG_NOOP(uname) \
252 static inline void SetPage##uname(struct page *page) { }
253
254 #define CLEARPAGEFLAG_NOOP(uname) \
255 static inline void ClearPage##uname(struct page *page) { }
256
257 #define __CLEARPAGEFLAG_NOOP(uname) \
258 static inline void __ClearPage##uname(struct page *page) { }
259
260 #define TESTSETFLAG_FALSE(uname) \
261 static inline int TestSetPage##uname(struct page *page) { return 0; }
262
263 #define TESTCLEARFLAG_FALSE(uname) \
264 static 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)
273 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
274 PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND)
275 PAGEFLAG(Referenced, referenced, PF_HEAD)
276 TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
277 __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
278 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
279 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
280 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
281 PAGEFLAG(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)
285 PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
286
287 /* Xen */
288 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
289 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
290 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
291 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
292
PAGEFLAG(Reserved,reserved,PF_NO_COMPOUND)293 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
294 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
295 PAGEFLAG(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 */
304 PAGEFLAG(Private, private, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY)
305 __CLEARPAGEFLAG(Private, private, PF_ANY)
306 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
307 PAGEFLAG(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 */
314 TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL)
315 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)
316 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
317
318 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
319 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
320 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
321 PAGEFLAG(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
331 PAGEFLAG_FALSE(HighMem)
332 #endif
333
334 #ifdef CONFIG_SWAP
335 static __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 }
343 SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
344 CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
345 #else
346 PAGEFLAG_FALSE(SwapCache)
347 #endif
348
349 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
350 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
351 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
352
353 #ifdef CONFIG_MMU
354 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
355 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
356 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
357 #else
358 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
359 TESTSCFLAG_FALSE(Mlocked)
360 #endif
361
362 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
363 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
364 #else
365 PAGEFLAG_FALSE(Uncached)
366 #endif
367
368 #ifdef CONFIG_MEMORY_FAILURE
369 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
370 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
371 #define __PG_HWPOISON (1UL << PG_hwpoison)
372 extern bool set_hwpoison_free_buddy_page(struct page *page);
373 #else
374 PAGEFLAG_FALSE(HWPoison)
375 static inline bool set_hwpoison_free_buddy_page(struct page *page)
376 {
377 return 0;
378 }
379 #define __PG_HWPOISON 0
380 #endif
381
382 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
TESTPAGEFLAG(Young,young,PF_ANY)383 TESTPAGEFLAG(Young, young, PF_ANY)
384 SETPAGEFLAG(Young, young, PF_ANY)
385 TESTCLEARFLAG(Young, young, PF_ANY)
386 PAGEFLAG(Idle, idle, PF_ANY)
387 #endif
388
389 /*
390 * On an anonymous page mapped into a user virtual memory area,
391 * page->mapping points to its anon_vma, not to a struct address_space;
392 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
393 *
394 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
395 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
396 * bit; and then page->mapping points, not to an anon_vma, but to a private
397 * structure which KSM associates with that merged page. See ksm.h.
398 *
399 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
400 * page and then page->mapping points a struct address_space.
401 *
402 * Please note that, confusingly, "page_mapping" refers to the inode
403 * address_space which maps the page from disk; whereas "page_mapped"
404 * refers to user virtual address space into which the page is mapped.
405 */
406 #define PAGE_MAPPING_ANON 0x1
407 #define PAGE_MAPPING_MOVABLE 0x2
408 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
409 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
410
411 static __always_inline int PageMappingFlags(struct page *page)
412 {
413 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
414 }
415
PageAnon(struct page * page)416 static __always_inline int PageAnon(struct page *page)
417 {
418 page = compound_head(page);
419 return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
420 }
421
__PageMovable(struct page * page)422 static __always_inline int __PageMovable(struct page *page)
423 {
424 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
425 PAGE_MAPPING_MOVABLE;
426 }
427
428 #ifdef CONFIG_KSM
429 /*
430 * A KSM page is one of those write-protected "shared pages" or "merged pages"
431 * which KSM maps into multiple mms, wherever identical anonymous page content
432 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
433 * anon_vma, but to that page's node of the stable tree.
434 */
PageKsm(struct page * page)435 static __always_inline int PageKsm(struct page *page)
436 {
437 page = compound_head(page);
438 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
439 PAGE_MAPPING_KSM;
440 }
441 #else
442 TESTPAGEFLAG_FALSE(Ksm)
443 #endif
444
445 u64 stable_page_flags(struct page *page);
446
PageUptodate(struct page * page)447 static inline int PageUptodate(struct page *page)
448 {
449 int ret;
450 page = compound_head(page);
451 ret = test_bit(PG_uptodate, &(page)->flags);
452 /*
453 * Must ensure that the data we read out of the page is loaded
454 * _after_ we've loaded page->flags to check for PageUptodate.
455 * We can skip the barrier if the page is not uptodate, because
456 * we wouldn't be reading anything from it.
457 *
458 * See SetPageUptodate() for the other side of the story.
459 */
460 if (ret)
461 smp_rmb();
462
463 return ret;
464 }
465
__SetPageUptodate(struct page * page)466 static __always_inline void __SetPageUptodate(struct page *page)
467 {
468 VM_BUG_ON_PAGE(PageTail(page), page);
469 smp_wmb();
470 __set_bit(PG_uptodate, &page->flags);
471 }
472
SetPageUptodate(struct page * page)473 static __always_inline void SetPageUptodate(struct page *page)
474 {
475 VM_BUG_ON_PAGE(PageTail(page), page);
476 /*
477 * Memory barrier must be issued before setting the PG_uptodate bit,
478 * so that all previous stores issued in order to bring the page
479 * uptodate are actually visible before PageUptodate becomes true.
480 */
481 smp_wmb();
482 set_bit(PG_uptodate, &page->flags);
483 }
484
485 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
486
487 int test_clear_page_writeback(struct page *page);
488 int __test_set_page_writeback(struct page *page, bool keep_write);
489
490 #define test_set_page_writeback(page) \
491 __test_set_page_writeback(page, false)
492 #define test_set_page_writeback_keepwrite(page) \
493 __test_set_page_writeback(page, true)
494
set_page_writeback(struct page * page)495 static inline void set_page_writeback(struct page *page)
496 {
497 test_set_page_writeback(page);
498 }
499
set_page_writeback_keepwrite(struct page * page)500 static inline void set_page_writeback_keepwrite(struct page *page)
501 {
502 test_set_page_writeback_keepwrite(page);
503 }
504
__PAGEFLAG(Head,head,PF_ANY)505 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
506
507 static __always_inline void set_compound_head(struct page *page, struct page *head)
508 {
509 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
510 }
511
clear_compound_head(struct page * page)512 static __always_inline void clear_compound_head(struct page *page)
513 {
514 WRITE_ONCE(page->compound_head, 0);
515 }
516
517 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
ClearPageCompound(struct page * page)518 static inline void ClearPageCompound(struct page *page)
519 {
520 BUG_ON(!PageHead(page));
521 ClearPageHead(page);
522 }
523 #endif
524
525 #define PG_head_mask ((1UL << PG_head))
526
527 #ifdef CONFIG_HUGETLB_PAGE
528 int PageHuge(struct page *page);
529 int PageHeadHuge(struct page *page);
530 bool page_huge_active(struct page *page);
531 #else
532 TESTPAGEFLAG_FALSE(Huge)
TESTPAGEFLAG_FALSE(HeadHuge)533 TESTPAGEFLAG_FALSE(HeadHuge)
534
535 static inline bool page_huge_active(struct page *page)
536 {
537 return 0;
538 }
539 #endif
540
541
542 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
543 /*
544 * PageHuge() only returns true for hugetlbfs pages, but not for
545 * normal or transparent huge pages.
546 *
547 * PageTransHuge() returns true for both transparent huge and
548 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
549 * called only in the core VM paths where hugetlbfs pages can't exist.
550 */
PageTransHuge(struct page * page)551 static inline int PageTransHuge(struct page *page)
552 {
553 VM_BUG_ON_PAGE(PageTail(page), page);
554 return PageHead(page);
555 }
556
557 /*
558 * PageTransCompound returns true for both transparent huge pages
559 * and hugetlbfs pages, so it should only be called when it's known
560 * that hugetlbfs pages aren't involved.
561 */
PageTransCompound(struct page * page)562 static inline int PageTransCompound(struct page *page)
563 {
564 return PageCompound(page);
565 }
566
567 /*
568 * PageTransCompoundMap is the same as PageTransCompound, but it also
569 * guarantees the primary MMU has the entire compound page mapped
570 * through pmd_trans_huge, which in turn guarantees the secondary MMUs
571 * can also map the entire compound page. This allows the secondary
572 * MMUs to call get_user_pages() only once for each compound page and
573 * to immediately map the entire compound page with a single secondary
574 * MMU fault. If there will be a pmd split later, the secondary MMUs
575 * will get an update through the MMU notifier invalidation through
576 * split_huge_pmd().
577 *
578 * Unlike PageTransCompound, this is safe to be called only while
579 * split_huge_pmd() cannot run from under us, like if protected by the
580 * MMU notifier, otherwise it may result in page->_mapcount < 0 false
581 * positives.
582 */
PageTransCompoundMap(struct page * page)583 static inline int PageTransCompoundMap(struct page *page)
584 {
585 return PageTransCompound(page) && atomic_read(&page->_mapcount) < 0;
586 }
587
588 /*
589 * PageTransTail returns true for both transparent huge pages
590 * and hugetlbfs pages, so it should only be called when it's known
591 * that hugetlbfs pages aren't involved.
592 */
PageTransTail(struct page * page)593 static inline int PageTransTail(struct page *page)
594 {
595 return PageTail(page);
596 }
597
598 /*
599 * PageDoubleMap indicates that the compound page is mapped with PTEs as well
600 * as PMDs.
601 *
602 * This is required for optimization of rmap operations for THP: we can postpone
603 * per small page mapcount accounting (and its overhead from atomic operations)
604 * until the first PMD split.
605 *
606 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
607 * by one. This reference will go away with last compound_mapcount.
608 *
609 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
610 */
PageDoubleMap(struct page * page)611 static inline int PageDoubleMap(struct page *page)
612 {
613 return PageHead(page) && test_bit(PG_double_map, &page[1].flags);
614 }
615
SetPageDoubleMap(struct page * page)616 static inline void SetPageDoubleMap(struct page *page)
617 {
618 VM_BUG_ON_PAGE(!PageHead(page), page);
619 set_bit(PG_double_map, &page[1].flags);
620 }
621
ClearPageDoubleMap(struct page * page)622 static inline void ClearPageDoubleMap(struct page *page)
623 {
624 VM_BUG_ON_PAGE(!PageHead(page), page);
625 clear_bit(PG_double_map, &page[1].flags);
626 }
TestSetPageDoubleMap(struct page * page)627 static inline int TestSetPageDoubleMap(struct page *page)
628 {
629 VM_BUG_ON_PAGE(!PageHead(page), page);
630 return test_and_set_bit(PG_double_map, &page[1].flags);
631 }
632
TestClearPageDoubleMap(struct page * page)633 static inline int TestClearPageDoubleMap(struct page *page)
634 {
635 VM_BUG_ON_PAGE(!PageHead(page), page);
636 return test_and_clear_bit(PG_double_map, &page[1].flags);
637 }
638
639 #else
640 TESTPAGEFLAG_FALSE(TransHuge)
641 TESTPAGEFLAG_FALSE(TransCompound)
642 TESTPAGEFLAG_FALSE(TransCompoundMap)
643 TESTPAGEFLAG_FALSE(TransTail)
644 PAGEFLAG_FALSE(DoubleMap)
645 TESTSETFLAG_FALSE(DoubleMap)
646 TESTCLEARFLAG_FALSE(DoubleMap)
647 #endif
648
649 /*
650 * For pages that are never mapped to userspace (and aren't PageSlab),
651 * page_type may be used. Because it is initialised to -1, we invert the
652 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
653 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
654 * low bits so that an underflow or overflow of page_mapcount() won't be
655 * mistaken for a page type value.
656 */
657
658 #define PAGE_TYPE_BASE 0xf0000000
659 /* Reserve 0x0000007f to catch underflows of page_mapcount */
660 #define PG_buddy 0x00000080
661 #define PG_balloon 0x00000100
662 #define PG_kmemcg 0x00000200
663 #define PG_table 0x00000400
664
665 #define PageType(page, flag) \
666 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
667
668 #define PAGE_TYPE_OPS(uname, lname) \
669 static __always_inline int Page##uname(struct page *page) \
670 { \
671 return PageType(page, PG_##lname); \
672 } \
673 static __always_inline void __SetPage##uname(struct page *page) \
674 { \
675 VM_BUG_ON_PAGE(!PageType(page, 0), page); \
676 page->page_type &= ~PG_##lname; \
677 } \
678 static __always_inline void __ClearPage##uname(struct page *page) \
679 { \
680 VM_BUG_ON_PAGE(!Page##uname(page), page); \
681 page->page_type |= PG_##lname; \
682 }
683
684 /*
685 * PageBuddy() indicates that the page is free and in the buddy system
686 * (see mm/page_alloc.c).
687 */
688 PAGE_TYPE_OPS(Buddy, buddy)
689
690 /*
691 * PageBalloon() is true for pages that are on the balloon page list
692 * (see mm/balloon_compaction.c).
693 */
694 PAGE_TYPE_OPS(Balloon, balloon)
695
696 /*
697 * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on
698 * pages allocated with __GFP_ACCOUNT. It gets cleared on page free.
699 */
700 PAGE_TYPE_OPS(Kmemcg, kmemcg)
701
702 /*
703 * Marks pages in use as page tables.
704 */
705 PAGE_TYPE_OPS(Table, table)
706
707 extern bool is_free_buddy_page(struct page *page);
708
709 __PAGEFLAG(Isolated, isolated, PF_ANY);
710
711 /*
712 * If network-based swap is enabled, sl*b must keep track of whether pages
713 * were allocated from pfmemalloc reserves.
714 */
PageSlabPfmemalloc(struct page * page)715 static inline int PageSlabPfmemalloc(struct page *page)
716 {
717 VM_BUG_ON_PAGE(!PageSlab(page), page);
718 return PageActive(page);
719 }
720
SetPageSlabPfmemalloc(struct page * page)721 static inline void SetPageSlabPfmemalloc(struct page *page)
722 {
723 VM_BUG_ON_PAGE(!PageSlab(page), page);
724 SetPageActive(page);
725 }
726
__ClearPageSlabPfmemalloc(struct page * page)727 static inline void __ClearPageSlabPfmemalloc(struct page *page)
728 {
729 VM_BUG_ON_PAGE(!PageSlab(page), page);
730 __ClearPageActive(page);
731 }
732
ClearPageSlabPfmemalloc(struct page * page)733 static inline void ClearPageSlabPfmemalloc(struct page *page)
734 {
735 VM_BUG_ON_PAGE(!PageSlab(page), page);
736 ClearPageActive(page);
737 }
738
739 #ifdef CONFIG_MMU
740 #define __PG_MLOCKED (1UL << PG_mlocked)
741 #else
742 #define __PG_MLOCKED 0
743 #endif
744
745 /*
746 * Flags checked when a page is freed. Pages being freed should not have
747 * these flags set. It they are, there is a problem.
748 */
749 #define PAGE_FLAGS_CHECK_AT_FREE \
750 (1UL << PG_lru | 1UL << PG_locked | \
751 1UL << PG_private | 1UL << PG_private_2 | \
752 1UL << PG_writeback | 1UL << PG_reserved | \
753 1UL << PG_slab | 1UL << PG_active | \
754 1UL << PG_unevictable | __PG_MLOCKED)
755
756 /*
757 * Flags checked when a page is prepped for return by the page allocator.
758 * Pages being prepped should not have these flags set. It they are set,
759 * there has been a kernel bug or struct page corruption.
760 *
761 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
762 * alloc-free cycle to prevent from reusing the page.
763 */
764 #define PAGE_FLAGS_CHECK_AT_PREP \
765 (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
766
767 #define PAGE_FLAGS_PRIVATE \
768 (1UL << PG_private | 1UL << PG_private_2)
769 /**
770 * page_has_private - Determine if page has private stuff
771 * @page: The page to be checked
772 *
773 * Determine if a page has private stuff, indicating that release routines
774 * should be invoked upon it.
775 */
page_has_private(struct page * page)776 static inline int page_has_private(struct page *page)
777 {
778 return !!(page->flags & PAGE_FLAGS_PRIVATE);
779 }
780
781 #undef PF_ANY
782 #undef PF_HEAD
783 #undef PF_ONLY_HEAD
784 #undef PF_NO_TAIL
785 #undef PF_NO_COMPOUND
786 #endif /* !__GENERATING_BOUNDS_H */
787
788 #endif /* PAGE_FLAGS_H */
789
