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_uptodate tells whether the page's contents is valid. When a read
72 * completes, the page becomes uptodate, unless a disk I/O error happened.
73 *
74 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
75 * file-backed pagecache (see mm/vmscan.c).
76 *
77 * PG_error is set to indicate that an I/O error occurred on this page.
78 *
79 * PG_arch_1 is an architecture specific page state bit. The generic code
80 * guarantees that this bit is cleared for a page when it first is entered into
81 * the page cache.
82 *
83 * PG_hwpoison indicates that a page got corrupted in hardware and contains
84 * data with incorrect ECC bits that triggered a machine check. Accessing is
85 * not safe since it may cause another machine check. Don't touch!
86 */
87
88 /*
89 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
90 * locked- and dirty-page accounting.
91 *
92 * The page flags field is split into two parts, the main flags area
93 * which extends from the low bits upwards, and the fields area which
94 * extends from the high bits downwards.
95 *
96 * | FIELD | ... | FLAGS |
97 * N-1 ^ 0
98 * (NR_PAGEFLAGS)
99 *
100 * The fields area is reserved for fields mapping zone, node (for NUMA) and
101 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like
102 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
103 */
104 enum pageflags {
105 PG_locked, /* Page is locked. Don't touch. */
106 PG_referenced,
107 PG_uptodate,
108 PG_dirty,
109 PG_lru,
110 PG_active,
111 PG_workingset,
112 PG_waiters, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
113 PG_error,
114 PG_slab,
115 PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
116 PG_arch_1,
117 PG_reserved,
118 PG_private, /* If pagecache, has fs-private data */
119 PG_private_2, /* If pagecache, has fs aux data */
120 PG_writeback, /* Page is under writeback */
121 PG_head, /* A head page */
122 PG_mappedtodisk, /* Has blocks allocated on-disk */
123 PG_reclaim, /* To be reclaimed asap */
124 PG_swapbacked, /* Page is backed by RAM/swap */
125 PG_unevictable, /* Page is "unevictable" */
126 #ifdef CONFIG_MMU
127 PG_mlocked, /* Page is vma mlocked */
128 #endif
129 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
130 PG_uncached, /* Page has been mapped as uncached */
131 #endif
132 #ifdef CONFIG_MEMORY_FAILURE
133 PG_hwpoison, /* hardware poisoned page. Don't touch */
134 #endif
135 #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
136 PG_young,
137 PG_idle,
138 #endif
139 #ifdef CONFIG_64BIT
140 PG_arch_2,
141 #endif
142 #ifdef CONFIG_KASAN_HW_TAGS
143 PG_skip_kasan_poison,
144 #endif
145 __NR_PAGEFLAGS,
146
147 /* Filesystems */
148 PG_checked = PG_owner_priv_1,
149
150 /* SwapBacked */
151 PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */
152
153 /* Two page bits are conscripted by FS-Cache to maintain local caching
154 * state. These bits are set on pages belonging to the netfs's inodes
155 * when those inodes are being locally cached.
156 */
157 PG_fscache = PG_private_2, /* page backed by cache */
158
159 /* XEN */
160 /* Pinned in Xen as a read-only pagetable page. */
161 PG_pinned = PG_owner_priv_1,
162 /* Pinned as part of domain save (see xen_mm_pin_all()). */
163 PG_savepinned = PG_dirty,
164 /* Has a grant mapping of another (foreign) domain's page. */
165 PG_foreign = PG_owner_priv_1,
166 /* Remapped by swiotlb-xen. */
167 PG_xen_remapped = PG_owner_priv_1,
168
169 /* SLOB */
170 PG_slob_free = PG_private,
171
172 /* Compound pages. Stored in first tail page's flags */
173 PG_double_map = PG_workingset,
174
175 /* non-lru isolated movable page */
176 PG_isolated = PG_reclaim,
177
178 /* Only valid for buddy pages. Used to track pages that are reported */
179 PG_reported = PG_uptodate,
180 };
181
182 #ifndef __GENERATING_BOUNDS_H
183
184 struct page; /* forward declaration */
185
compound_head(struct page * page)186 static inline struct page *compound_head(struct page *page)
187 {
188 unsigned long head = READ_ONCE(page->compound_head);
189
190 if (unlikely(head & 1))
191 return (struct page *) (head - 1);
192 return page;
193 }
194
PageTail(struct page * page)195 static __always_inline int PageTail(struct page *page)
196 {
197 return READ_ONCE(page->compound_head) & 1;
198 }
199
PageCompound(struct page * page)200 static __always_inline int PageCompound(struct page *page)
201 {
202 return test_bit(PG_head, &page->flags) || PageTail(page);
203 }
204
205 #define PAGE_POISON_PATTERN -1l
PagePoisoned(const struct page * page)206 static inline int PagePoisoned(const struct page *page)
207 {
208 return page->flags == PAGE_POISON_PATTERN;
209 }
210
211 #ifdef CONFIG_DEBUG_VM
212 void page_init_poison(struct page *page, size_t size);
213 #else
page_init_poison(struct page * page,size_t size)214 static inline void page_init_poison(struct page *page, size_t size)
215 {
216 }
217 #endif
218
219 /*
220 * Page flags policies wrt compound pages
221 *
222 * PF_POISONED_CHECK
223 * check if this struct page poisoned/uninitialized
224 *
225 * PF_ANY:
226 * the page flag is relevant for small, head and tail pages.
227 *
228 * PF_HEAD:
229 * for compound page all operations related to the page flag applied to
230 * head page.
231 *
232 * PF_ONLY_HEAD:
233 * for compound page, callers only ever operate on the head page.
234 *
235 * PF_NO_TAIL:
236 * modifications of the page flag must be done on small or head pages,
237 * checks can be done on tail pages too.
238 *
239 * PF_NO_COMPOUND:
240 * the page flag is not relevant for compound pages.
241 *
242 * PF_SECOND:
243 * the page flag is stored in the first tail page.
244 */
245 #define PF_POISONED_CHECK(page) ({ \
246 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \
247 page; })
248 #define PF_ANY(page, enforce) PF_POISONED_CHECK(page)
249 #define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page))
250 #define PF_ONLY_HEAD(page, enforce) ({ \
251 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
252 PF_POISONED_CHECK(page); })
253 #define PF_NO_TAIL(page, enforce) ({ \
254 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
255 PF_POISONED_CHECK(compound_head(page)); })
256 #define PF_NO_COMPOUND(page, enforce) ({ \
257 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
258 PF_POISONED_CHECK(page); })
259 #define PF_SECOND(page, enforce) ({ \
260 VM_BUG_ON_PGFLAGS(!PageHead(page), page); \
261 PF_POISONED_CHECK(&page[1]); })
262
263 /*
264 * Macros to create function definitions for page flags
265 */
266 #define TESTPAGEFLAG(uname, lname, policy) \
267 static __always_inline int Page##uname(struct page *page) \
268 { return test_bit(PG_##lname, &policy(page, 0)->flags); }
269
270 #define SETPAGEFLAG(uname, lname, policy) \
271 static __always_inline void SetPage##uname(struct page *page) \
272 { set_bit(PG_##lname, &policy(page, 1)->flags); }
273
274 #define CLEARPAGEFLAG(uname, lname, policy) \
275 static __always_inline void ClearPage##uname(struct page *page) \
276 { clear_bit(PG_##lname, &policy(page, 1)->flags); }
277
278 #define __SETPAGEFLAG(uname, lname, policy) \
279 static __always_inline void __SetPage##uname(struct page *page) \
280 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
281
282 #define __CLEARPAGEFLAG(uname, lname, policy) \
283 static __always_inline void __ClearPage##uname(struct page *page) \
284 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
285
286 #define TESTSETFLAG(uname, lname, policy) \
287 static __always_inline int TestSetPage##uname(struct page *page) \
288 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
289
290 #define TESTCLEARFLAG(uname, lname, policy) \
291 static __always_inline int TestClearPage##uname(struct page *page) \
292 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
293
294 #define PAGEFLAG(uname, lname, policy) \
295 TESTPAGEFLAG(uname, lname, policy) \
296 SETPAGEFLAG(uname, lname, policy) \
297 CLEARPAGEFLAG(uname, lname, policy)
298
299 #define __PAGEFLAG(uname, lname, policy) \
300 TESTPAGEFLAG(uname, lname, policy) \
301 __SETPAGEFLAG(uname, lname, policy) \
302 __CLEARPAGEFLAG(uname, lname, policy)
303
304 #define TESTSCFLAG(uname, lname, policy) \
305 TESTSETFLAG(uname, lname, policy) \
306 TESTCLEARFLAG(uname, lname, policy)
307
308 #define TESTPAGEFLAG_FALSE(uname) \
309 static inline int Page##uname(const struct page *page) { return 0; }
310
311 #define SETPAGEFLAG_NOOP(uname) \
312 static inline void SetPage##uname(struct page *page) { }
313
314 #define CLEARPAGEFLAG_NOOP(uname) \
315 static inline void ClearPage##uname(struct page *page) { }
316
317 #define __CLEARPAGEFLAG_NOOP(uname) \
318 static inline void __ClearPage##uname(struct page *page) { }
319
320 #define TESTSETFLAG_FALSE(uname) \
321 static inline int TestSetPage##uname(struct page *page) { return 0; }
322
323 #define TESTCLEARFLAG_FALSE(uname) \
324 static inline int TestClearPage##uname(struct page *page) { return 0; }
325
326 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \
327 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
328
329 #define TESTSCFLAG_FALSE(uname) \
330 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
331
332 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
333 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
334 PAGEFLAG(Error, error, PF_NO_TAIL) TESTCLEARFLAG(Error, error, PF_NO_TAIL)
335 PAGEFLAG(Referenced, referenced, PF_HEAD)
336 TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
337 __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
338 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
339 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
340 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
341 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
342 TESTCLEARFLAG(Active, active, PF_HEAD)
343 PAGEFLAG(Workingset, workingset, PF_HEAD)
344 TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
345 __PAGEFLAG(Slab, slab, PF_NO_TAIL)
346 __PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
347 PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
348
349 /* Xen */
350 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
351 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
352 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
353 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
PAGEFLAG(XenRemapped,xen_remapped,PF_NO_COMPOUND)354 PAGEFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
355 TESTCLEARFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
356
357 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
358 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
359 __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
360 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
361 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
362 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
363
364 /*
365 * Private page markings that may be used by the filesystem that owns the page
366 * for its own purposes.
367 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
368 */
369 PAGEFLAG(Private, private, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY)
370 __CLEARPAGEFLAG(Private, private, PF_ANY)
371 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
372 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
373 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
374
375 /*
376 * Only test-and-set exist for PG_writeback. The unconditional operators are
377 * risky: they bypass page accounting.
378 */
379 TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL)
380 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)
381 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
382
383 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
384 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
385 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
386 PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
387 TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
388
389 #ifdef CONFIG_HIGHMEM
390 /*
391 * Must use a macro here due to header dependency issues. page_zone() is not
392 * available at this point.
393 */
394 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
395 #else
396 PAGEFLAG_FALSE(HighMem)
397 #endif
398
399 #ifdef CONFIG_SWAP
400 static __always_inline int PageSwapCache(struct page *page)
401 {
402 #ifdef CONFIG_THP_SWAP
403 page = compound_head(page);
404 #endif
405 return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags);
406
407 }
408 SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
409 CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
410 #else
411 PAGEFLAG_FALSE(SwapCache)
412 #endif
413
414 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
415 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
416 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
417
418 #ifdef CONFIG_MMU
419 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
420 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
421 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
422 #else
423 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
424 TESTSCFLAG_FALSE(Mlocked)
425 #endif
426
427 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
428 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
429 #else
430 PAGEFLAG_FALSE(Uncached)
431 #endif
432
433 #ifdef CONFIG_MEMORY_FAILURE
434 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
435 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
436 #define __PG_HWPOISON (1UL << PG_hwpoison)
437 extern bool take_page_off_buddy(struct page *page);
438 #else
439 PAGEFLAG_FALSE(HWPoison)
440 #define __PG_HWPOISON 0
441 #endif
442
443 #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
TESTPAGEFLAG(Young,young,PF_ANY)444 TESTPAGEFLAG(Young, young, PF_ANY)
445 SETPAGEFLAG(Young, young, PF_ANY)
446 TESTCLEARFLAG(Young, young, PF_ANY)
447 PAGEFLAG(Idle, idle, PF_ANY)
448 #endif
449
450 #ifdef CONFIG_KASAN_HW_TAGS
451 PAGEFLAG(SkipKASanPoison, skip_kasan_poison, PF_HEAD)
452 #else
453 PAGEFLAG_FALSE(SkipKASanPoison)
454 #endif
455
456 /*
457 * PageReported() is used to track reported free pages within the Buddy
458 * allocator. We can use the non-atomic version of the test and set
459 * operations as both should be shielded with the zone lock to prevent
460 * any possible races on the setting or clearing of the bit.
461 */
462 __PAGEFLAG(Reported, reported, PF_NO_COMPOUND)
463
464 /*
465 * On an anonymous page mapped into a user virtual memory area,
466 * page->mapping points to its anon_vma, not to a struct address_space;
467 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
468 *
469 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
470 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
471 * bit; and then page->mapping points, not to an anon_vma, but to a private
472 * structure which KSM associates with that merged page. See ksm.h.
473 *
474 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
475 * page and then page->mapping points a struct address_space.
476 *
477 * Please note that, confusingly, "page_mapping" refers to the inode
478 * address_space which maps the page from disk; whereas "page_mapped"
479 * refers to user virtual address space into which the page is mapped.
480 */
481 #define PAGE_MAPPING_ANON 0x1
482 #define PAGE_MAPPING_MOVABLE 0x2
483 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
484 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
485
486 static __always_inline int PageMappingFlags(struct page *page)
487 {
488 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
489 }
490
PageAnon(struct page * page)491 static __always_inline int PageAnon(struct page *page)
492 {
493 page = compound_head(page);
494 return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
495 }
496
__PageMovable(struct page * page)497 static __always_inline int __PageMovable(struct page *page)
498 {
499 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
500 PAGE_MAPPING_MOVABLE;
501 }
502
503 #ifdef CONFIG_KSM
504 /*
505 * A KSM page is one of those write-protected "shared pages" or "merged pages"
506 * which KSM maps into multiple mms, wherever identical anonymous page content
507 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
508 * anon_vma, but to that page's node of the stable tree.
509 */
PageKsm(struct page * page)510 static __always_inline int PageKsm(struct page *page)
511 {
512 page = compound_head(page);
513 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
514 PAGE_MAPPING_KSM;
515 }
516 #else
517 TESTPAGEFLAG_FALSE(Ksm)
518 #endif
519
520 u64 stable_page_flags(struct page *page);
521
PageUptodate(struct page * page)522 static inline int PageUptodate(struct page *page)
523 {
524 int ret;
525 page = compound_head(page);
526 ret = test_bit(PG_uptodate, &(page)->flags);
527 /*
528 * Must ensure that the data we read out of the page is loaded
529 * _after_ we've loaded page->flags to check for PageUptodate.
530 * We can skip the barrier if the page is not uptodate, because
531 * we wouldn't be reading anything from it.
532 *
533 * See SetPageUptodate() for the other side of the story.
534 */
535 if (ret)
536 smp_rmb();
537
538 return ret;
539 }
540
__SetPageUptodate(struct page * page)541 static __always_inline void __SetPageUptodate(struct page *page)
542 {
543 VM_BUG_ON_PAGE(PageTail(page), page);
544 smp_wmb();
545 __set_bit(PG_uptodate, &page->flags);
546 }
547
SetPageUptodate(struct page * page)548 static __always_inline void SetPageUptodate(struct page *page)
549 {
550 VM_BUG_ON_PAGE(PageTail(page), page);
551 /*
552 * Memory barrier must be issued before setting the PG_uptodate bit,
553 * so that all previous stores issued in order to bring the page
554 * uptodate are actually visible before PageUptodate becomes true.
555 */
556 smp_wmb();
557 set_bit(PG_uptodate, &page->flags);
558 }
559
560 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
561
562 int test_clear_page_writeback(struct page *page);
563 int __test_set_page_writeback(struct page *page, bool keep_write);
564
565 #define test_set_page_writeback(page) \
566 __test_set_page_writeback(page, false)
567 #define test_set_page_writeback_keepwrite(page) \
568 __test_set_page_writeback(page, true)
569
set_page_writeback(struct page * page)570 static inline void set_page_writeback(struct page *page)
571 {
572 test_set_page_writeback(page);
573 }
574
set_page_writeback_keepwrite(struct page * page)575 static inline void set_page_writeback_keepwrite(struct page *page)
576 {
577 test_set_page_writeback_keepwrite(page);
578 }
579
__PAGEFLAG(Head,head,PF_ANY)580 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
581
582 static __always_inline void set_compound_head(struct page *page, struct page *head)
583 {
584 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
585 }
586
clear_compound_head(struct page * page)587 static __always_inline void clear_compound_head(struct page *page)
588 {
589 WRITE_ONCE(page->compound_head, 0);
590 }
591
592 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
ClearPageCompound(struct page * page)593 static inline void ClearPageCompound(struct page *page)
594 {
595 BUG_ON(!PageHead(page));
596 ClearPageHead(page);
597 }
598 #endif
599
600 #define PG_head_mask ((1UL << PG_head))
601
602 #ifdef CONFIG_HUGETLB_PAGE
603 int PageHuge(struct page *page);
604 int PageHeadHuge(struct page *page);
605 bool page_huge_active(struct page *page);
606 #else
607 TESTPAGEFLAG_FALSE(Huge)
TESTPAGEFLAG_FALSE(HeadHuge)608 TESTPAGEFLAG_FALSE(HeadHuge)
609
610 static inline bool page_huge_active(struct page *page)
611 {
612 return 0;
613 }
614 #endif
615
616
617 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
618 /*
619 * PageHuge() only returns true for hugetlbfs pages, but not for
620 * normal or transparent huge pages.
621 *
622 * PageTransHuge() returns true for both transparent huge and
623 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
624 * called only in the core VM paths where hugetlbfs pages can't exist.
625 */
PageTransHuge(struct page * page)626 static inline int PageTransHuge(struct page *page)
627 {
628 VM_BUG_ON_PAGE(PageTail(page), page);
629 return PageHead(page);
630 }
631
632 /*
633 * PageTransCompound returns true for both transparent huge pages
634 * and hugetlbfs pages, so it should only be called when it's known
635 * that hugetlbfs pages aren't involved.
636 */
PageTransCompound(struct page * page)637 static inline int PageTransCompound(struct page *page)
638 {
639 return PageCompound(page);
640 }
641
642 /*
643 * PageTransCompoundMap is the same as PageTransCompound, but it also
644 * guarantees the primary MMU has the entire compound page mapped
645 * through pmd_trans_huge, which in turn guarantees the secondary MMUs
646 * can also map the entire compound page. This allows the secondary
647 * MMUs to call get_user_pages() only once for each compound page and
648 * to immediately map the entire compound page with a single secondary
649 * MMU fault. If there will be a pmd split later, the secondary MMUs
650 * will get an update through the MMU notifier invalidation through
651 * split_huge_pmd().
652 *
653 * Unlike PageTransCompound, this is safe to be called only while
654 * split_huge_pmd() cannot run from under us, like if protected by the
655 * MMU notifier, otherwise it may result in page->_mapcount check false
656 * positives.
657 *
658 * We have to treat page cache THP differently since every subpage of it
659 * would get _mapcount inc'ed once it is PMD mapped. But, it may be PTE
660 * mapped in the current process so comparing subpage's _mapcount to
661 * compound_mapcount to filter out PTE mapped case.
662 */
PageTransCompoundMap(struct page * page)663 static inline int PageTransCompoundMap(struct page *page)
664 {
665 struct page *head;
666
667 if (!PageTransCompound(page))
668 return 0;
669
670 if (PageAnon(page))
671 return atomic_read(&page->_mapcount) < 0;
672
673 head = compound_head(page);
674 /* File THP is PMD mapped and not PTE mapped */
675 return atomic_read(&page->_mapcount) ==
676 atomic_read(compound_mapcount_ptr(head));
677 }
678
679 /*
680 * PageTransTail returns true for both transparent huge pages
681 * and hugetlbfs pages, so it should only be called when it's known
682 * that hugetlbfs pages aren't involved.
683 */
PageTransTail(struct page * page)684 static inline int PageTransTail(struct page *page)
685 {
686 return PageTail(page);
687 }
688
689 /*
690 * PageDoubleMap indicates that the compound page is mapped with PTEs as well
691 * as PMDs.
692 *
693 * This is required for optimization of rmap operations for THP: we can postpone
694 * per small page mapcount accounting (and its overhead from atomic operations)
695 * until the first PMD split.
696 *
697 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
698 * by one. This reference will go away with last compound_mapcount.
699 *
700 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
701 */
PAGEFLAG(DoubleMap,double_map,PF_SECOND)702 PAGEFLAG(DoubleMap, double_map, PF_SECOND)
703 TESTSCFLAG(DoubleMap, double_map, PF_SECOND)
704 #else
705 TESTPAGEFLAG_FALSE(TransHuge)
706 TESTPAGEFLAG_FALSE(TransCompound)
707 TESTPAGEFLAG_FALSE(TransCompoundMap)
708 TESTPAGEFLAG_FALSE(TransTail)
709 PAGEFLAG_FALSE(DoubleMap)
710 TESTSCFLAG_FALSE(DoubleMap)
711 #endif
712
713 /*
714 * For pages that are never mapped to userspace (and aren't PageSlab),
715 * page_type may be used. Because it is initialised to -1, we invert the
716 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
717 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
718 * low bits so that an underflow or overflow of page_mapcount() won't be
719 * mistaken for a page type value.
720 */
721
722 #define PAGE_TYPE_BASE 0xf0000000
723 /* Reserve 0x0000007f to catch underflows of page_mapcount */
724 #define PAGE_MAPCOUNT_RESERVE -128
725 #define PG_buddy 0x00000080
726 #define PG_offline 0x00000100
727 #define PG_kmemcg 0x00000200
728 #define PG_table 0x00000400
729 #define PG_guard 0x00000800
730
731 #define PageType(page, flag) \
732 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
733
734 static inline int page_has_type(struct page *page)
735 {
736 return (int)page->page_type < PAGE_MAPCOUNT_RESERVE;
737 }
738
739 #define PAGE_TYPE_OPS(uname, lname) \
740 static __always_inline int Page##uname(struct page *page) \
741 { \
742 return PageType(page, PG_##lname); \
743 } \
744 static __always_inline void __SetPage##uname(struct page *page) \
745 { \
746 VM_BUG_ON_PAGE(!PageType(page, 0), page); \
747 page->page_type &= ~PG_##lname; \
748 } \
749 static __always_inline void __ClearPage##uname(struct page *page) \
750 { \
751 VM_BUG_ON_PAGE(!Page##uname(page), page); \
752 page->page_type |= PG_##lname; \
753 }
754
755 /*
756 * PageBuddy() indicates that the page is free and in the buddy system
757 * (see mm/page_alloc.c).
758 */
759 PAGE_TYPE_OPS(Buddy, buddy)
760
761 /*
762 * PageOffline() indicates that the page is logically offline although the
763 * containing section is online. (e.g. inflated in a balloon driver or
764 * not onlined when onlining the section).
765 * The content of these pages is effectively stale. Such pages should not
766 * be touched (read/write/dump/save) except by their owner.
767 *
768 * If a driver wants to allow to offline unmovable PageOffline() pages without
769 * putting them back to the buddy, it can do so via the memory notifier by
770 * decrementing the reference count in MEM_GOING_OFFLINE and incrementing the
771 * reference count in MEM_CANCEL_OFFLINE. When offlining, the PageOffline()
772 * pages (now with a reference count of zero) are treated like free pages,
773 * allowing the containing memory block to get offlined. A driver that
774 * relies on this feature is aware that re-onlining the memory block will
775 * require to re-set the pages PageOffline() and not giving them to the
776 * buddy via online_page_callback_t.
777 */
778 PAGE_TYPE_OPS(Offline, offline)
779
780 /*
781 * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on
782 * pages allocated with __GFP_ACCOUNT. It gets cleared on page free.
783 */
784 PAGE_TYPE_OPS(Kmemcg, kmemcg)
785
786 /*
787 * Marks pages in use as page tables.
788 */
789 PAGE_TYPE_OPS(Table, table)
790
791 /*
792 * Marks guardpages used with debug_pagealloc.
793 */
794 PAGE_TYPE_OPS(Guard, guard)
795
796 extern bool is_free_buddy_page(struct page *page);
797
798 PAGEFLAG(Isolated, isolated, PF_ANY);
799
800 /*
801 * If network-based swap is enabled, sl*b must keep track of whether pages
802 * were allocated from pfmemalloc reserves.
803 */
PageSlabPfmemalloc(struct page * page)804 static inline int PageSlabPfmemalloc(struct page *page)
805 {
806 VM_BUG_ON_PAGE(!PageSlab(page), page);
807 return PageActive(page);
808 }
809
SetPageSlabPfmemalloc(struct page * page)810 static inline void SetPageSlabPfmemalloc(struct page *page)
811 {
812 VM_BUG_ON_PAGE(!PageSlab(page), page);
813 SetPageActive(page);
814 }
815
__ClearPageSlabPfmemalloc(struct page * page)816 static inline void __ClearPageSlabPfmemalloc(struct page *page)
817 {
818 VM_BUG_ON_PAGE(!PageSlab(page), page);
819 __ClearPageActive(page);
820 }
821
ClearPageSlabPfmemalloc(struct page * page)822 static inline void ClearPageSlabPfmemalloc(struct page *page)
823 {
824 VM_BUG_ON_PAGE(!PageSlab(page), page);
825 ClearPageActive(page);
826 }
827
828 #ifdef CONFIG_MMU
829 #define __PG_MLOCKED (1UL << PG_mlocked)
830 #else
831 #define __PG_MLOCKED 0
832 #endif
833
834 /*
835 * Flags checked when a page is freed. Pages being freed should not have
836 * these flags set. It they are, there is a problem.
837 */
838 #define PAGE_FLAGS_CHECK_AT_FREE \
839 (1UL << PG_lru | 1UL << PG_locked | \
840 1UL << PG_private | 1UL << PG_private_2 | \
841 1UL << PG_writeback | 1UL << PG_reserved | \
842 1UL << PG_slab | 1UL << PG_active | \
843 1UL << PG_unevictable | __PG_MLOCKED)
844
845 /*
846 * Flags checked when a page is prepped for return by the page allocator.
847 * Pages being prepped should not have these flags set. It they are set,
848 * there has been a kernel bug or struct page corruption.
849 *
850 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
851 * alloc-free cycle to prevent from reusing the page.
852 */
853 #define PAGE_FLAGS_CHECK_AT_PREP \
854 (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
855
856 #define PAGE_FLAGS_PRIVATE \
857 (1UL << PG_private | 1UL << PG_private_2)
858 /**
859 * page_has_private - Determine if page has private stuff
860 * @page: The page to be checked
861 *
862 * Determine if a page has private stuff, indicating that release routines
863 * should be invoked upon it.
864 */
page_has_private(struct page * page)865 static inline int page_has_private(struct page *page)
866 {
867 return !!(page->flags & PAGE_FLAGS_PRIVATE);
868 }
869
870 #undef PF_ANY
871 #undef PF_HEAD
872 #undef PF_ONLY_HEAD
873 #undef PF_NO_TAIL
874 #undef PF_NO_COMPOUND
875 #undef PF_SECOND
876 #endif /* !__GENERATING_BOUNDS_H */
877
878 #endif /* PAGE_FLAGS_H */
879