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_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).
70 *
71 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
72 * file-backed pagecache (see mm/vmscan.c).
73 *
74 * PG_error is set to indicate that an I/O error occurred on this page.
75 *
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
78 * the page cache.
79 *
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!
83 */
84
85 /*
86 * Don't use the pageflags directly. Use the PageFoo macros.
87 *
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.
91 *
92 * | FIELD | ... | FLAGS |
93 * N-1 ^ 0
94 * (NR_PAGEFLAGS)
95 *
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).
99 */
100 enum pageflags {
101 PG_locked, /* Page is locked. Don't touch. */
102 PG_writeback, /* Page is under writeback */
103 PG_referenced,
104 PG_uptodate,
105 PG_dirty,
106 PG_lru,
107 PG_head, /* Must be in bit 6 */
108 PG_waiters, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
109 PG_active,
110 PG_workingset,
111 PG_error,
112 PG_slab,
113 PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
114 PG_arch_1,
115 PG_reserved,
116 PG_private, /* If pagecache, has fs-private data */
117 PG_private_2, /* If pagecache, has fs aux data */
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" */
122 #ifdef CONFIG_MMU
123 PG_mlocked, /* Page is vma mlocked */
124 #endif
125 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
126 PG_uncached, /* Page has been mapped as uncached */
127 #endif
128 #ifdef CONFIG_MEMORY_FAILURE
129 PG_hwpoison, /* hardware poisoned page. Don't touch */
130 #endif
131 #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
132 PG_young,
133 PG_idle,
134 #endif
135 #ifdef CONFIG_ARCH_USES_PG_ARCH_X
136 PG_arch_2,
137 PG_arch_3,
138 #endif
139 __NR_PAGEFLAGS,
140
141 PG_readahead = PG_reclaim,
142
143 /*
144 * Depending on the way an anonymous folio can be mapped into a page
145 * table (e.g., single PMD/PUD/CONT of the head page vs. PTE-mapped
146 * THP), PG_anon_exclusive may be set only for the head page or for
147 * tail pages of an anonymous folio. For now, we only expect it to be
148 * set on tail pages for PTE-mapped THP.
149 */
150 PG_anon_exclusive = PG_mappedtodisk,
151
152 /* Filesystems */
153 PG_checked = PG_owner_priv_1,
154
155 /* SwapBacked */
156 PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */
157
158 /* Two page bits are conscripted by FS-Cache to maintain local caching
159 * state. These bits are set on pages belonging to the netfs's inodes
160 * when those inodes are being locally cached.
161 */
162 PG_fscache = PG_private_2, /* page backed by cache */
163
164 /* XEN */
165 /* Pinned in Xen as a read-only pagetable page. */
166 PG_pinned = PG_owner_priv_1,
167 /* Pinned as part of domain save (see xen_mm_pin_all()). */
168 PG_savepinned = PG_dirty,
169 /* Has a grant mapping of another (foreign) domain's page. */
170 PG_foreign = PG_owner_priv_1,
171 /* Remapped by swiotlb-xen. */
172 PG_xen_remapped = PG_owner_priv_1,
173
174 /* non-lru isolated movable page */
175 PG_isolated = PG_reclaim,
176
177 /* Only valid for buddy pages. Used to track pages that are reported */
178 PG_reported = PG_uptodate,
179
180 #ifdef CONFIG_MEMORY_HOTPLUG
181 /* For self-hosted memmap pages */
182 PG_vmemmap_self_hosted = PG_owner_priv_1,
183 #endif
184
185 /*
186 * Flags only valid for compound pages. Stored in first tail page's
187 * flags word. Cannot use the first 8 flags or any flag marked as
188 * PF_ANY.
189 */
190
191 /* At least one page in this folio has the hwpoison flag set */
192 PG_has_hwpoisoned = PG_error,
193 PG_large_rmappable = PG_workingset, /* anon or file-backed */
194 };
195
196 #define PAGEFLAGS_MASK ((1UL << NR_PAGEFLAGS) - 1)
197
198 #ifndef __GENERATING_BOUNDS_H
199
200 #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
201 DECLARE_STATIC_KEY_FALSE(hugetlb_optimize_vmemmap_key);
202
203 /*
204 * Return the real head page struct iff the @page is a fake head page, otherwise
205 * return the @page itself. See Documentation/mm/vmemmap_dedup.rst.
206 */
page_fixed_fake_head(const struct page * page)207 static __always_inline const struct page *page_fixed_fake_head(const struct page *page)
208 {
209 if (!static_branch_unlikely(&hugetlb_optimize_vmemmap_key))
210 return page;
211
212 /*
213 * Only addresses aligned with PAGE_SIZE of struct page may be fake head
214 * struct page. The alignment check aims to avoid access the fields (
215 * e.g. compound_head) of the @page[1]. It can avoid touch a (possibly)
216 * cold cacheline in some cases.
217 */
218 if (IS_ALIGNED((unsigned long)page, PAGE_SIZE) &&
219 test_bit(PG_head, &page->flags)) {
220 /*
221 * We can safely access the field of the @page[1] with PG_head
222 * because the @page is a compound page composed with at least
223 * two contiguous pages.
224 */
225 unsigned long head = READ_ONCE(page[1].compound_head);
226
227 if (likely(head & 1))
228 return (const struct page *)(head - 1);
229 }
230 return page;
231 }
232 #else
page_fixed_fake_head(const struct page * page)233 static inline const struct page *page_fixed_fake_head(const struct page *page)
234 {
235 return page;
236 }
237 #endif
238
page_is_fake_head(struct page * page)239 static __always_inline int page_is_fake_head(struct page *page)
240 {
241 return page_fixed_fake_head(page) != page;
242 }
243
_compound_head(const struct page * page)244 static inline unsigned long _compound_head(const struct page *page)
245 {
246 unsigned long head = READ_ONCE(page->compound_head);
247
248 if (unlikely(head & 1))
249 return head - 1;
250 return (unsigned long)page_fixed_fake_head(page);
251 }
252
253 #define compound_head(page) ((typeof(page))_compound_head(page))
254
255 /**
256 * page_folio - Converts from page to folio.
257 * @p: The page.
258 *
259 * Every page is part of a folio. This function cannot be called on a
260 * NULL pointer.
261 *
262 * Context: No reference, nor lock is required on @page. If the caller
263 * does not hold a reference, this call may race with a folio split, so
264 * it should re-check the folio still contains this page after gaining
265 * a reference on the folio.
266 * Return: The folio which contains this page.
267 */
268 #define page_folio(p) (_Generic((p), \
269 const struct page *: (const struct folio *)_compound_head(p), \
270 struct page *: (struct folio *)_compound_head(p)))
271
272 /**
273 * folio_page - Return a page from a folio.
274 * @folio: The folio.
275 * @n: The page number to return.
276 *
277 * @n is relative to the start of the folio. This function does not
278 * check that the page number lies within @folio; the caller is presumed
279 * to have a reference to the page.
280 */
281 #define folio_page(folio, n) nth_page(&(folio)->page, n)
282
PageTail(struct page * page)283 static __always_inline int PageTail(struct page *page)
284 {
285 return READ_ONCE(page->compound_head) & 1 || page_is_fake_head(page);
286 }
287
PageCompound(struct page * page)288 static __always_inline int PageCompound(struct page *page)
289 {
290 return test_bit(PG_head, &page->flags) ||
291 READ_ONCE(page->compound_head) & 1;
292 }
293
294 #define PAGE_POISON_PATTERN -1l
PagePoisoned(const struct page * page)295 static inline int PagePoisoned(const struct page *page)
296 {
297 return READ_ONCE(page->flags) == PAGE_POISON_PATTERN;
298 }
299
300 #ifdef CONFIG_DEBUG_VM
301 void page_init_poison(struct page *page, size_t size);
302 #else
page_init_poison(struct page * page,size_t size)303 static inline void page_init_poison(struct page *page, size_t size)
304 {
305 }
306 #endif
307
folio_flags(struct folio * folio,unsigned n)308 static unsigned long *folio_flags(struct folio *folio, unsigned n)
309 {
310 struct page *page = &folio->page;
311
312 VM_BUG_ON_PGFLAGS(PageTail(page), page);
313 VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags), page);
314 return &page[n].flags;
315 }
316
317 /*
318 * Page flags policies wrt compound pages
319 *
320 * PF_POISONED_CHECK
321 * check if this struct page poisoned/uninitialized
322 *
323 * PF_ANY:
324 * the page flag is relevant for small, head and tail pages.
325 *
326 * PF_HEAD:
327 * for compound page all operations related to the page flag applied to
328 * head page.
329 *
330 * PF_ONLY_HEAD:
331 * for compound page, callers only ever operate on the head page.
332 *
333 * PF_NO_TAIL:
334 * modifications of the page flag must be done on small or head pages,
335 * checks can be done on tail pages too.
336 *
337 * PF_NO_COMPOUND:
338 * the page flag is not relevant for compound pages.
339 *
340 * PF_SECOND:
341 * the page flag is stored in the first tail page.
342 */
343 #define PF_POISONED_CHECK(page) ({ \
344 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \
345 page; })
346 #define PF_ANY(page, enforce) PF_POISONED_CHECK(page)
347 #define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page))
348 #define PF_ONLY_HEAD(page, enforce) ({ \
349 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
350 PF_POISONED_CHECK(page); })
351 #define PF_NO_TAIL(page, enforce) ({ \
352 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
353 PF_POISONED_CHECK(compound_head(page)); })
354 #define PF_NO_COMPOUND(page, enforce) ({ \
355 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
356 PF_POISONED_CHECK(page); })
357 #define PF_SECOND(page, enforce) ({ \
358 VM_BUG_ON_PGFLAGS(!PageHead(page), page); \
359 PF_POISONED_CHECK(&page[1]); })
360
361 /* Which page is the flag stored in */
362 #define FOLIO_PF_ANY 0
363 #define FOLIO_PF_HEAD 0
364 #define FOLIO_PF_ONLY_HEAD 0
365 #define FOLIO_PF_NO_TAIL 0
366 #define FOLIO_PF_NO_COMPOUND 0
367 #define FOLIO_PF_SECOND 1
368
369 /*
370 * Macros to create function definitions for page flags
371 */
372 #define TESTPAGEFLAG(uname, lname, policy) \
373 static __always_inline bool folio_test_##lname(struct folio *folio) \
374 { return test_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
375 static __always_inline int Page##uname(struct page *page) \
376 { return test_bit(PG_##lname, &policy(page, 0)->flags); }
377
378 #define SETPAGEFLAG(uname, lname, policy) \
379 static __always_inline \
380 void folio_set_##lname(struct folio *folio) \
381 { set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
382 static __always_inline void SetPage##uname(struct page *page) \
383 { set_bit(PG_##lname, &policy(page, 1)->flags); }
384
385 #define CLEARPAGEFLAG(uname, lname, policy) \
386 static __always_inline \
387 void folio_clear_##lname(struct folio *folio) \
388 { clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
389 static __always_inline void ClearPage##uname(struct page *page) \
390 { clear_bit(PG_##lname, &policy(page, 1)->flags); }
391
392 #define __SETPAGEFLAG(uname, lname, policy) \
393 static __always_inline \
394 void __folio_set_##lname(struct folio *folio) \
395 { __set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
396 static __always_inline void __SetPage##uname(struct page *page) \
397 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
398
399 #define __CLEARPAGEFLAG(uname, lname, policy) \
400 static __always_inline \
401 void __folio_clear_##lname(struct folio *folio) \
402 { __clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
403 static __always_inline void __ClearPage##uname(struct page *page) \
404 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
405
406 #define TESTSETFLAG(uname, lname, policy) \
407 static __always_inline \
408 bool folio_test_set_##lname(struct folio *folio) \
409 { return test_and_set_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
410 static __always_inline int TestSetPage##uname(struct page *page) \
411 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
412
413 #define TESTCLEARFLAG(uname, lname, policy) \
414 static __always_inline \
415 bool folio_test_clear_##lname(struct folio *folio) \
416 { return test_and_clear_bit(PG_##lname, folio_flags(folio, FOLIO_##policy)); } \
417 static __always_inline int TestClearPage##uname(struct page *page) \
418 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
419
420 #define PAGEFLAG(uname, lname, policy) \
421 TESTPAGEFLAG(uname, lname, policy) \
422 SETPAGEFLAG(uname, lname, policy) \
423 CLEARPAGEFLAG(uname, lname, policy)
424
425 #define __PAGEFLAG(uname, lname, policy) \
426 TESTPAGEFLAG(uname, lname, policy) \
427 __SETPAGEFLAG(uname, lname, policy) \
428 __CLEARPAGEFLAG(uname, lname, policy)
429
430 #define TESTSCFLAG(uname, lname, policy) \
431 TESTSETFLAG(uname, lname, policy) \
432 TESTCLEARFLAG(uname, lname, policy)
433
434 #define FOLIO_TEST_FLAG_FALSE(name) \
435 static inline bool folio_test_##name(const struct folio *folio) \
436 { return false; }
437 #define FOLIO_SET_FLAG_NOOP(name) \
438 static inline void folio_set_##name(struct folio *folio) { }
439 #define FOLIO_CLEAR_FLAG_NOOP(name) \
440 static inline void folio_clear_##name(struct folio *folio) { }
441 #define __FOLIO_SET_FLAG_NOOP(name) \
442 static inline void __folio_set_##name(struct folio *folio) { }
443 #define __FOLIO_CLEAR_FLAG_NOOP(name) \
444 static inline void __folio_clear_##name(struct folio *folio) { }
445 #define FOLIO_TEST_SET_FLAG_FALSE(name) \
446 static inline bool folio_test_set_##name(struct folio *folio) \
447 { return false; }
448 #define FOLIO_TEST_CLEAR_FLAG_FALSE(name) \
449 static inline bool folio_test_clear_##name(struct folio *folio) \
450 { return false; }
451
452 #define FOLIO_FLAG_FALSE(name) \
453 FOLIO_TEST_FLAG_FALSE(name) \
454 FOLIO_SET_FLAG_NOOP(name) \
455 FOLIO_CLEAR_FLAG_NOOP(name)
456
457 #define TESTPAGEFLAG_FALSE(uname, lname) \
458 FOLIO_TEST_FLAG_FALSE(lname) \
459 static inline int Page##uname(const struct page *page) { return 0; }
460
461 #define SETPAGEFLAG_NOOP(uname, lname) \
462 FOLIO_SET_FLAG_NOOP(lname) \
463 static inline void SetPage##uname(struct page *page) { }
464
465 #define CLEARPAGEFLAG_NOOP(uname, lname) \
466 FOLIO_CLEAR_FLAG_NOOP(lname) \
467 static inline void ClearPage##uname(struct page *page) { }
468
469 #define __CLEARPAGEFLAG_NOOP(uname, lname) \
470 __FOLIO_CLEAR_FLAG_NOOP(lname) \
471 static inline void __ClearPage##uname(struct page *page) { }
472
473 #define TESTSETFLAG_FALSE(uname, lname) \
474 FOLIO_TEST_SET_FLAG_FALSE(lname) \
475 static inline int TestSetPage##uname(struct page *page) { return 0; }
476
477 #define TESTCLEARFLAG_FALSE(uname, lname) \
478 FOLIO_TEST_CLEAR_FLAG_FALSE(lname) \
479 static inline int TestClearPage##uname(struct page *page) { return 0; }
480
481 #define PAGEFLAG_FALSE(uname, lname) TESTPAGEFLAG_FALSE(uname, lname) \
482 SETPAGEFLAG_NOOP(uname, lname) CLEARPAGEFLAG_NOOP(uname, lname)
483
484 #define TESTSCFLAG_FALSE(uname, lname) \
485 TESTSETFLAG_FALSE(uname, lname) TESTCLEARFLAG_FALSE(uname, lname)
486
487 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
488 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
489 PAGEFLAG(Error, error, PF_NO_TAIL) TESTCLEARFLAG(Error, error, PF_NO_TAIL)
490 PAGEFLAG(Referenced, referenced, PF_HEAD)
491 TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
492 __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
493 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
494 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
495 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
496 TESTCLEARFLAG(LRU, lru, PF_HEAD)
497 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
498 TESTCLEARFLAG(Active, active, PF_HEAD)
499 PAGEFLAG(Workingset, workingset, PF_HEAD)
500 TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
501 __PAGEFLAG(Slab, slab, PF_NO_TAIL)
502 PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
503
504 /* Xen */
505 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
506 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
507 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
508 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
PAGEFLAG(XenRemapped,xen_remapped,PF_NO_COMPOUND)509 PAGEFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
510 TESTCLEARFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
511
512 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
513 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
514 __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
515 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
516 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
517 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
518
519 /*
520 * Private page markings that may be used by the filesystem that owns the page
521 * for its own purposes.
522 * - PG_private and PG_private_2 cause release_folio() and co to be invoked
523 */
524 PAGEFLAG(Private, private, PF_ANY)
525 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
526 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
527 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
528
529 /*
530 * Only test-and-set exist for PG_writeback. The unconditional operators are
531 * risky: they bypass page accounting.
532 */
533 TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL)
534 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)
535 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
536
537 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
538 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
539 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
540 PAGEFLAG(Readahead, readahead, PF_NO_COMPOUND)
541 TESTCLEARFLAG(Readahead, readahead, PF_NO_COMPOUND)
542
543 #ifdef CONFIG_HIGHMEM
544 /*
545 * Must use a macro here due to header dependency issues. page_zone() is not
546 * available at this point.
547 */
548 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
549 #define folio_test_highmem(__f) is_highmem_idx(folio_zonenum(__f))
550 #else
551 PAGEFLAG_FALSE(HighMem, highmem)
552 #endif
553
554 /* Does kmap_local_folio() only allow access to one page of the folio? */
555 #ifdef CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP
556 #define folio_test_partial_kmap(f) true
557 #else
558 #define folio_test_partial_kmap(f) folio_test_highmem(f)
559 #endif
560
561 #ifdef CONFIG_SWAP
562 static __always_inline bool folio_test_swapcache(struct folio *folio)
563 {
564 return folio_test_swapbacked(folio) &&
565 test_bit(PG_swapcache, folio_flags(folio, 0));
566 }
567
PageSwapCache(struct page * page)568 static __always_inline bool PageSwapCache(struct page *page)
569 {
570 return folio_test_swapcache(page_folio(page));
571 }
572
573 SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
574 CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
575 #else
576 PAGEFLAG_FALSE(SwapCache, swapcache)
577 #endif
578
579 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
580 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
581 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
582
583 #ifdef CONFIG_MMU
584 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
585 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
586 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
587 #else
588 PAGEFLAG_FALSE(Mlocked, mlocked) __CLEARPAGEFLAG_NOOP(Mlocked, mlocked)
589 TESTSCFLAG_FALSE(Mlocked, mlocked)
590 #endif
591
592 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
593 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
594 #else
595 PAGEFLAG_FALSE(Uncached, uncached)
596 #endif
597
598 #ifdef CONFIG_MEMORY_FAILURE
599 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
600 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
601 #define __PG_HWPOISON (1UL << PG_hwpoison)
602 #define MAGIC_HWPOISON 0x48575053U /* HWPS */
603 extern void SetPageHWPoisonTakenOff(struct page *page);
604 extern void ClearPageHWPoisonTakenOff(struct page *page);
605 extern bool take_page_off_buddy(struct page *page);
606 extern bool put_page_back_buddy(struct page *page);
607 #else
608 PAGEFLAG_FALSE(HWPoison, hwpoison)
609 #define __PG_HWPOISON 0
610 #endif
611
612 #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
TESTPAGEFLAG(Young,young,PF_ANY)613 TESTPAGEFLAG(Young, young, PF_ANY)
614 SETPAGEFLAG(Young, young, PF_ANY)
615 TESTCLEARFLAG(Young, young, PF_ANY)
616 PAGEFLAG(Idle, idle, PF_ANY)
617 #endif
618
619 /*
620 * PageReported() is used to track reported free pages within the Buddy
621 * allocator. We can use the non-atomic version of the test and set
622 * operations as both should be shielded with the zone lock to prevent
623 * any possible races on the setting or clearing of the bit.
624 */
625 __PAGEFLAG(Reported, reported, PF_NO_COMPOUND)
626
627 #ifdef CONFIG_MEMORY_HOTPLUG
628 PAGEFLAG(VmemmapSelfHosted, vmemmap_self_hosted, PF_ANY)
629 #else
630 PAGEFLAG_FALSE(VmemmapSelfHosted, vmemmap_self_hosted)
631 #endif
632
633 /*
634 * On an anonymous page mapped into a user virtual memory area,
635 * page->mapping points to its anon_vma, not to a struct address_space;
636 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
637 *
638 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
639 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
640 * bit; and then page->mapping points, not to an anon_vma, but to a private
641 * structure which KSM associates with that merged page. See ksm.h.
642 *
643 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
644 * page and then page->mapping points to a struct movable_operations.
645 *
646 * Please note that, confusingly, "page_mapping" refers to the inode
647 * address_space which maps the page from disk; whereas "page_mapped"
648 * refers to user virtual address space into which the page is mapped.
649 *
650 * For slab pages, since slab reuses the bits in struct page to store its
651 * internal states, the page->mapping does not exist as such, nor do these
652 * flags below. So in order to avoid testing non-existent bits, please
653 * make sure that PageSlab(page) actually evaluates to false before calling
654 * the following functions (e.g., PageAnon). See mm/slab.h.
655 */
656 #define PAGE_MAPPING_ANON 0x1
657 #define PAGE_MAPPING_MOVABLE 0x2
658 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
659 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
660
661 /*
662 * Different with flags above, this flag is used only for fsdax mode. It
663 * indicates that this page->mapping is now under reflink case.
664 */
665 #define PAGE_MAPPING_DAX_SHARED ((void *)0x1)
666
667 static __always_inline bool folio_mapping_flags(struct folio *folio)
668 {
669 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) != 0;
670 }
671
PageMappingFlags(struct page * page)672 static __always_inline int PageMappingFlags(struct page *page)
673 {
674 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
675 }
676
folio_test_anon(struct folio * folio)677 static __always_inline bool folio_test_anon(struct folio *folio)
678 {
679 return ((unsigned long)folio->mapping & PAGE_MAPPING_ANON) != 0;
680 }
681
PageAnon(struct page * page)682 static __always_inline bool PageAnon(struct page *page)
683 {
684 return folio_test_anon(page_folio(page));
685 }
686
__folio_test_movable(const struct folio * folio)687 static __always_inline bool __folio_test_movable(const struct folio *folio)
688 {
689 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
690 PAGE_MAPPING_MOVABLE;
691 }
692
__PageMovable(struct page * page)693 static __always_inline int __PageMovable(struct page *page)
694 {
695 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
696 PAGE_MAPPING_MOVABLE;
697 }
698
699 #ifdef CONFIG_KSM
700 /*
701 * A KSM page is one of those write-protected "shared pages" or "merged pages"
702 * which KSM maps into multiple mms, wherever identical anonymous page content
703 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
704 * anon_vma, but to that page's node of the stable tree.
705 */
folio_test_ksm(struct folio * folio)706 static __always_inline bool folio_test_ksm(struct folio *folio)
707 {
708 return ((unsigned long)folio->mapping & PAGE_MAPPING_FLAGS) ==
709 PAGE_MAPPING_KSM;
710 }
711
PageKsm(struct page * page)712 static __always_inline bool PageKsm(struct page *page)
713 {
714 return folio_test_ksm(page_folio(page));
715 }
716 #else
717 TESTPAGEFLAG_FALSE(Ksm, ksm)
718 #endif
719
720 u64 stable_page_flags(struct page *page);
721
722 /**
723 * folio_test_uptodate - Is this folio up to date?
724 * @folio: The folio.
725 *
726 * The uptodate flag is set on a folio when every byte in the folio is
727 * at least as new as the corresponding bytes on storage. Anonymous
728 * and CoW folios are always uptodate. If the folio is not uptodate,
729 * some of the bytes in it may be; see the is_partially_uptodate()
730 * address_space operation.
731 */
folio_test_uptodate(struct folio * folio)732 static inline bool folio_test_uptodate(struct folio *folio)
733 {
734 bool ret = test_bit(PG_uptodate, folio_flags(folio, 0));
735 /*
736 * Must ensure that the data we read out of the folio is loaded
737 * _after_ we've loaded folio->flags to check the uptodate bit.
738 * We can skip the barrier if the folio is not uptodate, because
739 * we wouldn't be reading anything from it.
740 *
741 * See folio_mark_uptodate() for the other side of the story.
742 */
743 if (ret)
744 smp_rmb();
745
746 return ret;
747 }
748
PageUptodate(struct page * page)749 static inline int PageUptodate(struct page *page)
750 {
751 return folio_test_uptodate(page_folio(page));
752 }
753
__folio_mark_uptodate(struct folio * folio)754 static __always_inline void __folio_mark_uptodate(struct folio *folio)
755 {
756 smp_wmb();
757 __set_bit(PG_uptodate, folio_flags(folio, 0));
758 }
759
folio_mark_uptodate(struct folio * folio)760 static __always_inline void folio_mark_uptodate(struct folio *folio)
761 {
762 /*
763 * Memory barrier must be issued before setting the PG_uptodate bit,
764 * so that all previous stores issued in order to bring the folio
765 * uptodate are actually visible before folio_test_uptodate becomes true.
766 */
767 smp_wmb();
768 set_bit(PG_uptodate, folio_flags(folio, 0));
769 }
770
__SetPageUptodate(struct page * page)771 static __always_inline void __SetPageUptodate(struct page *page)
772 {
773 __folio_mark_uptodate((struct folio *)page);
774 }
775
SetPageUptodate(struct page * page)776 static __always_inline void SetPageUptodate(struct page *page)
777 {
778 folio_mark_uptodate((struct folio *)page);
779 }
780
781 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
782
783 bool __folio_start_writeback(struct folio *folio, bool keep_write);
784 bool set_page_writeback(struct page *page);
785
786 #define folio_start_writeback(folio) \
787 __folio_start_writeback(folio, false)
788 #define folio_start_writeback_keepwrite(folio) \
789 __folio_start_writeback(folio, true)
790
test_set_page_writeback(struct page * page)791 static inline bool test_set_page_writeback(struct page *page)
792 {
793 return set_page_writeback(page);
794 }
795
folio_test_head(struct folio * folio)796 static __always_inline bool folio_test_head(struct folio *folio)
797 {
798 return test_bit(PG_head, folio_flags(folio, FOLIO_PF_ANY));
799 }
800
PageHead(struct page * page)801 static __always_inline int PageHead(struct page *page)
802 {
803 PF_POISONED_CHECK(page);
804 return test_bit(PG_head, &page->flags) && !page_is_fake_head(page);
805 }
806
__SETPAGEFLAG(Head,head,PF_ANY)807 __SETPAGEFLAG(Head, head, PF_ANY)
808 __CLEARPAGEFLAG(Head, head, PF_ANY)
809 CLEARPAGEFLAG(Head, head, PF_ANY)
810
811 /**
812 * folio_test_large() - Does this folio contain more than one page?
813 * @folio: The folio to test.
814 *
815 * Return: True if the folio is larger than one page.
816 */
817 static inline bool folio_test_large(struct folio *folio)
818 {
819 return folio_test_head(folio);
820 }
821
set_compound_head(struct page * page,struct page * head)822 static __always_inline void set_compound_head(struct page *page, struct page *head)
823 {
824 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
825 }
826
clear_compound_head(struct page * page)827 static __always_inline void clear_compound_head(struct page *page)
828 {
829 WRITE_ONCE(page->compound_head, 0);
830 }
831
832 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
ClearPageCompound(struct page * page)833 static inline void ClearPageCompound(struct page *page)
834 {
835 BUG_ON(!PageHead(page));
836 ClearPageHead(page);
837 }
PAGEFLAG(LargeRmappable,large_rmappable,PF_SECOND)838 PAGEFLAG(LargeRmappable, large_rmappable, PF_SECOND)
839 #else
840 TESTPAGEFLAG_FALSE(LargeRmappable, large_rmappable)
841 #endif
842
843 #define PG_head_mask ((1UL << PG_head))
844
845 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
846 /*
847 * PageHuge() only returns true for hugetlbfs pages, but not for
848 * normal or transparent huge pages.
849 *
850 * PageTransHuge() returns true for both transparent huge and
851 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
852 * called only in the core VM paths where hugetlbfs pages can't exist.
853 */
854 static inline int PageTransHuge(struct page *page)
855 {
856 VM_BUG_ON_PAGE(PageTail(page), page);
857 return PageHead(page);
858 }
859
860 /*
861 * PageTransCompound returns true for both transparent huge pages
862 * and hugetlbfs pages, so it should only be called when it's known
863 * that hugetlbfs pages aren't involved.
864 */
PageTransCompound(struct page * page)865 static inline int PageTransCompound(struct page *page)
866 {
867 return PageCompound(page);
868 }
869
870 /*
871 * PageTransTail returns true for both transparent huge pages
872 * and hugetlbfs pages, so it should only be called when it's known
873 * that hugetlbfs pages aren't involved.
874 */
PageTransTail(struct page * page)875 static inline int PageTransTail(struct page *page)
876 {
877 return PageTail(page);
878 }
879 #else
880 TESTPAGEFLAG_FALSE(TransHuge, transhuge)
881 TESTPAGEFLAG_FALSE(TransCompound, transcompound)
882 TESTPAGEFLAG_FALSE(TransCompoundMap, transcompoundmap)
883 TESTPAGEFLAG_FALSE(TransTail, transtail)
884 #endif
885
886 #if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
887 /*
888 * PageHasHWPoisoned indicates that at least one subpage is hwpoisoned in the
889 * compound page.
890 *
891 * This flag is set by hwpoison handler. Cleared by THP split or free page.
892 */
PAGEFLAG(HasHWPoisoned,has_hwpoisoned,PF_SECOND)893 PAGEFLAG(HasHWPoisoned, has_hwpoisoned, PF_SECOND)
894 TESTSCFLAG(HasHWPoisoned, has_hwpoisoned, PF_SECOND)
895 #else
896 PAGEFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
897 TESTSCFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
898 #endif
899
900 /*
901 * For pages that are never mapped to userspace (and aren't PageSlab),
902 * page_type may be used. Because it is initialised to -1, we invert the
903 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
904 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
905 * low bits so that an underflow or overflow of _mapcount won't be
906 * mistaken for a page type value.
907 */
908
909 #define PAGE_TYPE_BASE 0xf0000000
910 /* Reserve 0x0000007f to catch underflows of _mapcount */
911 #define PAGE_MAPCOUNT_RESERVE -128
912 #define PG_buddy 0x00000080
913 #define PG_offline 0x00000100
914 #define PG_table 0x00000200
915 #define PG_guard 0x00000400
916 #define PG_hugetlb 0x00000800
917
918 #define PageType(page, flag) \
919 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
920 #define folio_test_type(folio, flag) \
921 ((folio->page.page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
922
923 static inline int page_type_has_type(unsigned int page_type)
924 {
925 return (int)page_type < PAGE_MAPCOUNT_RESERVE;
926 }
927
page_has_type(struct page * page)928 static inline int page_has_type(struct page *page)
929 {
930 return page_type_has_type(page->page_type);
931 }
932
933 #define FOLIO_TYPE_OPS(lname, fname) \
934 static __always_inline bool folio_test_##fname(const struct folio *folio)\
935 { \
936 return folio_test_type(folio, PG_##lname); \
937 } \
938 static __always_inline void __folio_set_##fname(struct folio *folio) \
939 { \
940 VM_BUG_ON_FOLIO(!folio_test_type(folio, 0), folio); \
941 folio->page.page_type &= ~PG_##lname; \
942 } \
943 static __always_inline void __folio_clear_##fname(struct folio *folio) \
944 { \
945 VM_BUG_ON_FOLIO(!folio_test_##fname(folio), folio); \
946 folio->page.page_type |= PG_##lname; \
947 }
948
949 #define PAGE_TYPE_OPS(uname, lname, fname) \
950 FOLIO_TYPE_OPS(lname, fname) \
951 static __always_inline int Page##uname(const struct page *page) \
952 { \
953 return PageType(page, PG_##lname); \
954 } \
955 static __always_inline void __SetPage##uname(struct page *page) \
956 { \
957 VM_BUG_ON_PAGE(!PageType(page, 0), page); \
958 page->page_type &= ~PG_##lname; \
959 } \
960 static __always_inline void __ClearPage##uname(struct page *page) \
961 { \
962 VM_BUG_ON_PAGE(!Page##uname(page), page); \
963 page->page_type |= PG_##lname; \
964 }
965
966 /*
967 * PageBuddy() indicates that the page is free and in the buddy system
968 * (see mm/page_alloc.c).
969 */
970 PAGE_TYPE_OPS(Buddy, buddy, buddy)
971
972 /*
973 * PageOffline() indicates that the page is logically offline although the
974 * containing section is online. (e.g. inflated in a balloon driver or
975 * not onlined when onlining the section).
976 * The content of these pages is effectively stale. Such pages should not
977 * be touched (read/write/dump/save) except by their owner.
978 *
979 * If a driver wants to allow to offline unmovable PageOffline() pages without
980 * putting them back to the buddy, it can do so via the memory notifier by
981 * decrementing the reference count in MEM_GOING_OFFLINE and incrementing the
982 * reference count in MEM_CANCEL_OFFLINE. When offlining, the PageOffline()
983 * pages (now with a reference count of zero) are treated like free pages,
984 * allowing the containing memory block to get offlined. A driver that
985 * relies on this feature is aware that re-onlining the memory block will
986 * require to re-set the pages PageOffline() and not giving them to the
987 * buddy via online_page_callback_t.
988 *
989 * There are drivers that mark a page PageOffline() and expect there won't be
990 * any further access to page content. PFN walkers that read content of random
991 * pages should check PageOffline() and synchronize with such drivers using
992 * page_offline_freeze()/page_offline_thaw().
993 */
994 PAGE_TYPE_OPS(Offline, offline, offline)
995
996 extern void page_offline_freeze(void);
997 extern void page_offline_thaw(void);
998 extern void page_offline_begin(void);
999 extern void page_offline_end(void);
1000
1001 /*
1002 * Marks pages in use as page tables.
1003 */
PAGE_TYPE_OPS(Table,table,pgtable)1004 PAGE_TYPE_OPS(Table, table, pgtable)
1005
1006 /*
1007 * Marks guardpages used with debug_pagealloc.
1008 */
1009 PAGE_TYPE_OPS(Guard, guard, guard)
1010
1011 #ifdef CONFIG_HUGETLB_PAGE
1012 FOLIO_TYPE_OPS(hugetlb, hugetlb)
1013 #else
1014 FOLIO_TEST_FLAG_FALSE(hugetlb)
1015 #endif
1016
1017 /**
1018 * PageHuge - Determine if the page belongs to hugetlbfs
1019 * @page: The page to test.
1020 *
1021 * Context: Any context.
1022 * Return: True for hugetlbfs pages, false for anon pages or pages
1023 * belonging to other filesystems.
1024 */
1025 static inline bool PageHuge(const struct page *page)
1026 {
1027 return folio_test_hugetlb(page_folio(page));
1028 }
1029
1030 /*
1031 * Check if a page is currently marked HWPoisoned. Note that this check is
1032 * best effort only and inherently racy: there is no way to synchronize with
1033 * failing hardware.
1034 */
is_page_hwpoison(struct page * page)1035 static inline bool is_page_hwpoison(struct page *page)
1036 {
1037 if (PageHWPoison(page))
1038 return true;
1039 return PageHuge(page) && PageHWPoison(compound_head(page));
1040 }
1041
1042 extern bool is_free_buddy_page(struct page *page);
1043
1044 PAGEFLAG(Isolated, isolated, PF_ANY);
1045
PageAnonExclusive(struct page * page)1046 static __always_inline int PageAnonExclusive(struct page *page)
1047 {
1048 VM_BUG_ON_PGFLAGS(!PageAnon(page), page);
1049 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1050 return test_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1051 }
1052
SetPageAnonExclusive(struct page * page)1053 static __always_inline void SetPageAnonExclusive(struct page *page)
1054 {
1055 VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
1056 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1057 set_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1058 }
1059
ClearPageAnonExclusive(struct page * page)1060 static __always_inline void ClearPageAnonExclusive(struct page *page)
1061 {
1062 VM_BUG_ON_PGFLAGS(!PageAnon(page) || PageKsm(page), page);
1063 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1064 clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1065 }
1066
__ClearPageAnonExclusive(struct page * page)1067 static __always_inline void __ClearPageAnonExclusive(struct page *page)
1068 {
1069 VM_BUG_ON_PGFLAGS(!PageAnon(page), page);
1070 VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page);
1071 __clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags);
1072 }
1073
1074 #ifdef CONFIG_MMU
1075 #define __PG_MLOCKED (1UL << PG_mlocked)
1076 #else
1077 #define __PG_MLOCKED 0
1078 #endif
1079
1080 /*
1081 * Flags checked when a page is freed. Pages being freed should not have
1082 * these flags set. If they are, there is a problem.
1083 */
1084 #define PAGE_FLAGS_CHECK_AT_FREE \
1085 (1UL << PG_lru | 1UL << PG_locked | \
1086 1UL << PG_private | 1UL << PG_private_2 | \
1087 1UL << PG_writeback | 1UL << PG_reserved | \
1088 1UL << PG_slab | 1UL << PG_active | \
1089 1UL << PG_unevictable | __PG_MLOCKED | LRU_GEN_MASK)
1090
1091 /*
1092 * Flags checked when a page is prepped for return by the page allocator.
1093 * Pages being prepped should not have these flags set. If they are set,
1094 * there has been a kernel bug or struct page corruption.
1095 *
1096 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
1097 * alloc-free cycle to prevent from reusing the page.
1098 */
1099 #define PAGE_FLAGS_CHECK_AT_PREP \
1100 ((PAGEFLAGS_MASK & ~__PG_HWPOISON) | LRU_GEN_MASK | LRU_REFS_MASK)
1101
1102 /*
1103 * Flags stored in the second page of a compound page. They may overlap
1104 * the CHECK_AT_FREE flags above, so need to be cleared.
1105 */
1106 #define PAGE_FLAGS_SECOND \
1107 (0xffUL /* order */ | 1UL << PG_has_hwpoisoned | \
1108 1UL << PG_large_rmappable)
1109
1110 #define PAGE_FLAGS_PRIVATE \
1111 (1UL << PG_private | 1UL << PG_private_2)
1112 /**
1113 * page_has_private - Determine if page has private stuff
1114 * @page: The page to be checked
1115 *
1116 * Determine if a page has private stuff, indicating that release routines
1117 * should be invoked upon it.
1118 */
page_has_private(struct page * page)1119 static inline int page_has_private(struct page *page)
1120 {
1121 return !!(page->flags & PAGE_FLAGS_PRIVATE);
1122 }
1123
folio_has_private(struct folio * folio)1124 static inline bool folio_has_private(struct folio *folio)
1125 {
1126 return page_has_private(&folio->page);
1127 }
1128
1129 #undef PF_ANY
1130 #undef PF_HEAD
1131 #undef PF_ONLY_HEAD
1132 #undef PF_NO_TAIL
1133 #undef PF_NO_COMPOUND
1134 #undef PF_SECOND
1135 #endif /* !__GENERATING_BOUNDS_H */
1136
1137 #endif /* PAGE_FLAGS_H */
1138