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_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
136 PG_young,
137 PG_idle,
138 #endif
139 #ifdef CONFIG_64BIT
140 PG_arch_2,
141 #endif
142 #ifdef CONFIG_PAGE_TRACING
143 PG_skb,
144 PG_zspage,
145 #endif
146 #ifdef CONFIG_MEM_PURGEABLE
147 PG_purgeable,
148 #endif
149 #ifdef CONFIG_SECURITY_XPM
150 PG_xpm_readonly,
151 PG_xpm_writetainted,
152 #endif
153 __NR_PAGEFLAGS,
154
155 /* Filesystems */
156 PG_checked = PG_owner_priv_1,
157
158 /* SwapBacked */
159 PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */
160
161 /* Two page bits are conscripted by FS-Cache to maintain local caching
162 * state. These bits are set on pages belonging to the netfs's inodes
163 * when those inodes are being locally cached.
164 */
165 PG_fscache = PG_private_2, /* page backed by cache */
166
167 /* XEN */
168 /* Pinned in Xen as a read-only pagetable page. */
169 PG_pinned = PG_owner_priv_1,
170 /* Pinned as part of domain save (see xen_mm_pin_all()). */
171 PG_savepinned = PG_dirty,
172 /* Has a grant mapping of another (foreign) domain's page. */
173 PG_foreign = PG_owner_priv_1,
174 /* Remapped by swiotlb-xen. */
175 PG_xen_remapped = PG_owner_priv_1,
176
177 /* SLOB */
178 PG_slob_free = PG_private,
179
180 /* Compound pages. Stored in first tail page's flags */
181 PG_double_map = PG_workingset,
182
183 /* non-lru isolated movable page */
184 PG_isolated = PG_reclaim,
185
186 /* Only valid for buddy pages. Used to track pages that are reported */
187 PG_reported = PG_uptodate,
188 };
189
190 #ifndef __GENERATING_BOUNDS_H
191
192 struct page; /* forward declaration */
193
compound_head(struct page * page)194 static inline struct page *compound_head(struct page *page)
195 {
196 unsigned long head = READ_ONCE(page->compound_head);
197
198 if (unlikely(head & 1))
199 return (struct page *) (head - 1);
200 return page;
201 }
202
PageTail(struct page * page)203 static __always_inline int PageTail(struct page *page)
204 {
205 return READ_ONCE(page->compound_head) & 1;
206 }
207
PageCompound(struct page * page)208 static __always_inline int PageCompound(struct page *page)
209 {
210 return test_bit(PG_head, &page->flags) || PageTail(page);
211 }
212
213 #define PAGE_POISON_PATTERN -1l
PagePoisoned(const struct page * page)214 static inline int PagePoisoned(const struct page *page)
215 {
216 return page->flags == PAGE_POISON_PATTERN;
217 }
218
219 #ifdef CONFIG_DEBUG_VM
220 void page_init_poison(struct page *page, size_t size);
221 #else
page_init_poison(struct page * page,size_t size)222 static inline void page_init_poison(struct page *page, size_t size)
223 {
224 }
225 #endif
226
227 /*
228 * Page flags policies wrt compound pages
229 *
230 * PF_POISONED_CHECK
231 * check if this struct page poisoned/uninitialized
232 *
233 * PF_ANY:
234 * the page flag is relevant for small, head and tail pages.
235 *
236 * PF_HEAD:
237 * for compound page all operations related to the page flag applied to
238 * head page.
239 *
240 * PF_ONLY_HEAD:
241 * for compound page, callers only ever operate on the head page.
242 *
243 * PF_NO_TAIL:
244 * modifications of the page flag must be done on small or head pages,
245 * checks can be done on tail pages too.
246 *
247 * PF_NO_COMPOUND:
248 * the page flag is not relevant for compound pages.
249 *
250 * PF_SECOND:
251 * the page flag is stored in the first tail page.
252 */
253 #define PF_POISONED_CHECK(page) ({ \
254 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \
255 page; })
256 #define PF_ANY(page, enforce) PF_POISONED_CHECK(page)
257 #define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page))
258 #define PF_ONLY_HEAD(page, enforce) ({ \
259 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
260 PF_POISONED_CHECK(page); })
261 #define PF_NO_TAIL(page, enforce) ({ \
262 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
263 PF_POISONED_CHECK(compound_head(page)); })
264 #define PF_NO_COMPOUND(page, enforce) ({ \
265 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
266 PF_POISONED_CHECK(page); })
267 #define PF_SECOND(page, enforce) ({ \
268 VM_BUG_ON_PGFLAGS(!PageHead(page), page); \
269 PF_POISONED_CHECK(&page[1]); })
270
271 /*
272 * Macros to create function definitions for page flags
273 */
274 #define TESTPAGEFLAG(uname, lname, policy) \
275 static __always_inline int Page##uname(struct page *page) \
276 { return test_bit(PG_##lname, &policy(page, 0)->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 __SETPAGEFLAG(uname, lname, policy) \
287 static __always_inline void __SetPage##uname(struct page *page) \
288 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
289
290 #define __CLEARPAGEFLAG(uname, lname, policy) \
291 static __always_inline void __ClearPage##uname(struct page *page) \
292 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
293
294 #define TESTSETFLAG(uname, lname, policy) \
295 static __always_inline int TestSetPage##uname(struct page *page) \
296 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
297
298 #define TESTCLEARFLAG(uname, lname, policy) \
299 static __always_inline int TestClearPage##uname(struct page *page) \
300 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
301
302 #define PAGEFLAG(uname, lname, policy) \
303 TESTPAGEFLAG(uname, lname, policy) \
304 SETPAGEFLAG(uname, lname, policy) \
305 CLEARPAGEFLAG(uname, lname, policy)
306
307 #define __PAGEFLAG(uname, lname, policy) \
308 TESTPAGEFLAG(uname, lname, policy) \
309 __SETPAGEFLAG(uname, lname, policy) \
310 __CLEARPAGEFLAG(uname, lname, policy)
311
312 #define TESTSCFLAG(uname, lname, policy) \
313 TESTSETFLAG(uname, lname, policy) \
314 TESTCLEARFLAG(uname, lname, policy)
315
316 #define TESTPAGEFLAG_FALSE(uname) \
317 static inline int Page##uname(const struct page *page) { return 0; }
318
319 #define SETPAGEFLAG_NOOP(uname) \
320 static inline void SetPage##uname(struct page *page) { }
321
322 #define CLEARPAGEFLAG_NOOP(uname) \
323 static inline void ClearPage##uname(struct page *page) { }
324
325 #define __CLEARPAGEFLAG_NOOP(uname) \
326 static inline void __ClearPage##uname(struct page *page) { }
327
328 #define TESTSETFLAG_FALSE(uname) \
329 static inline int TestSetPage##uname(struct page *page) { return 0; }
330
331 #define TESTCLEARFLAG_FALSE(uname) \
332 static inline int TestClearPage##uname(struct page *page) { return 0; }
333
334 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \
335 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
336
337 #define TESTSCFLAG_FALSE(uname) \
338 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
339
340 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
341 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
342 PAGEFLAG(Error, error, PF_NO_TAIL) TESTCLEARFLAG(Error, error, PF_NO_TAIL)
343 PAGEFLAG(Referenced, referenced, PF_HEAD)
344 TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
345 __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
346 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
347 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
348 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
349 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
350 TESTCLEARFLAG(Active, active, PF_HEAD)
351 PAGEFLAG(Workingset, workingset, PF_HEAD)
352 TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
353 __PAGEFLAG(Slab, slab, PF_NO_TAIL)
354 __PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
355 PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
356
357 #ifdef CONFIG_SECURITY_XPM
358 PAGEFLAG(XPMReadonly, xpm_readonly, PF_HEAD)
359 PAGEFLAG(XPMWritetainted, xpm_writetainted, PF_HEAD)
360 #else
361 PAGEFLAG_FALSE(XPMReadonly)
362 PAGEFLAG_FALSE(XPMWritetainted)
363 #endif
364
365 /* Xen */
366 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
367 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
368 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
369 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
PAGEFLAG(XenRemapped,xen_remapped,PF_NO_COMPOUND)370 PAGEFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
371 TESTCLEARFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
372
373 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
374 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
375 __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
376 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
377 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
378 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
379
380 /*
381 * Private page markings that may be used by the filesystem that owns the page
382 * for its own purposes.
383 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
384 */
385 PAGEFLAG(Private, private, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY)
386 __CLEARPAGEFLAG(Private, private, PF_ANY)
387 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
388 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
389 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
390
391 /*
392 * Only test-and-set exist for PG_writeback. The unconditional operators are
393 * risky: they bypass page accounting.
394 */
395 TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL)
396 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)
397 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
398
399 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
400 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
401 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
402 PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
403 TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
404
405 #ifdef CONFIG_HIGHMEM
406 /*
407 * Must use a macro here due to header dependency issues. page_zone() is not
408 * available at this point.
409 */
410 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
411 #else
412 PAGEFLAG_FALSE(HighMem)
413 #endif
414
415 #ifdef CONFIG_SWAP
416 static __always_inline int PageSwapCache(struct page *page)
417 {
418 #ifdef CONFIG_THP_SWAP
419 page = compound_head(page);
420 #endif
421 return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags);
422
423 }
424 SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
425 CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
426 #else
427 PAGEFLAG_FALSE(SwapCache)
428 #endif
429
430 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
431 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
432 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
433
434 #ifdef CONFIG_MMU
435 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
436 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
437 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
438 #else
439 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
440 TESTSCFLAG_FALSE(Mlocked)
441 #endif
442
443 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
444 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
445 #else
446 PAGEFLAG_FALSE(Uncached)
447 #endif
448
449 #ifdef CONFIG_MEMORY_FAILURE
450 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
451 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
452 #define __PG_HWPOISON (1UL << PG_hwpoison)
453 extern bool take_page_off_buddy(struct page *page);
454 #else
455 PAGEFLAG_FALSE(HWPoison)
456 #define __PG_HWPOISON 0
457 #endif
458
459 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
TESTPAGEFLAG(Young,young,PF_ANY)460 TESTPAGEFLAG(Young, young, PF_ANY)
461 SETPAGEFLAG(Young, young, PF_ANY)
462 TESTCLEARFLAG(Young, young, PF_ANY)
463 PAGEFLAG(Idle, idle, PF_ANY)
464 #endif
465
466 #ifdef CONFIG_PAGE_TRACING
467 PAGEFLAG(SKB, skb, PF_ANY)
468 PAGEFLAG(Zspage, zspage, PF_ANY)
469 #endif
470
471 /*
472 * PageReported() is used to track reported free pages within the Buddy
473 * allocator. We can use the non-atomic version of the test and set
474 * operations as both should be shielded with the zone lock to prevent
475 * any possible races on the setting or clearing of the bit.
476 */
477 __PAGEFLAG(Reported, reported, PF_NO_COMPOUND)
478
479 #ifdef CONFIG_MEM_PURGEABLE
480 PAGEFLAG(Purgeable, purgeable, PF_ANY)
481 #else
482 PAGEFLAG_FALSE(Purgeable)
483 #endif
484 /*
485 * On an anonymous page mapped into a user virtual memory area,
486 * page->mapping points to its anon_vma, not to a struct address_space;
487 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
488 *
489 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
490 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
491 * bit; and then page->mapping points, not to an anon_vma, but to a private
492 * structure which KSM associates with that merged page. See ksm.h.
493 *
494 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
495 * page and then page->mapping points a struct address_space.
496 *
497 * Please note that, confusingly, "page_mapping" refers to the inode
498 * address_space which maps the page from disk; whereas "page_mapped"
499 * refers to user virtual address space into which the page is mapped.
500 */
501 #define PAGE_MAPPING_ANON 0x1
502 #define PAGE_MAPPING_MOVABLE 0x2
503 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
504 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
505
506 static __always_inline int PageMappingFlags(struct page *page)
507 {
508 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
509 }
510
PageAnon(struct page * page)511 static __always_inline int PageAnon(struct page *page)
512 {
513 page = compound_head(page);
514 return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
515 }
516
__PageMovable(struct page * page)517 static __always_inline int __PageMovable(struct page *page)
518 {
519 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
520 PAGE_MAPPING_MOVABLE;
521 }
522
523 #ifdef CONFIG_KSM
524 /*
525 * A KSM page is one of those write-protected "shared pages" or "merged pages"
526 * which KSM maps into multiple mms, wherever identical anonymous page content
527 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
528 * anon_vma, but to that page's node of the stable tree.
529 */
PageKsm(struct page * page)530 static __always_inline int PageKsm(struct page *page)
531 {
532 page = compound_head(page);
533 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
534 PAGE_MAPPING_KSM;
535 }
536 #else
537 TESTPAGEFLAG_FALSE(Ksm)
538 #endif
539
540 u64 stable_page_flags(struct page *page);
541
PageUptodate(struct page * page)542 static inline int PageUptodate(struct page *page)
543 {
544 int ret;
545 page = compound_head(page);
546 ret = test_bit(PG_uptodate, &(page)->flags);
547 /*
548 * Must ensure that the data we read out of the page is loaded
549 * _after_ we've loaded page->flags to check for PageUptodate.
550 * We can skip the barrier if the page is not uptodate, because
551 * we wouldn't be reading anything from it.
552 *
553 * See SetPageUptodate() for the other side of the story.
554 */
555 if (ret)
556 smp_rmb();
557
558 return ret;
559 }
560
__SetPageUptodate(struct page * page)561 static __always_inline void __SetPageUptodate(struct page *page)
562 {
563 VM_BUG_ON_PAGE(PageTail(page), page);
564 smp_wmb();
565 __set_bit(PG_uptodate, &page->flags);
566 }
567
SetPageUptodate(struct page * page)568 static __always_inline void SetPageUptodate(struct page *page)
569 {
570 VM_BUG_ON_PAGE(PageTail(page), page);
571 /*
572 * Memory barrier must be issued before setting the PG_uptodate bit,
573 * so that all previous stores issued in order to bring the page
574 * uptodate are actually visible before PageUptodate becomes true.
575 */
576 smp_wmb();
577 set_bit(PG_uptodate, &page->flags);
578 }
579
580 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
581
582 int test_clear_page_writeback(struct page *page);
583 int __test_set_page_writeback(struct page *page, bool keep_write);
584
585 #define test_set_page_writeback(page) \
586 __test_set_page_writeback(page, false)
587 #define test_set_page_writeback_keepwrite(page) \
588 __test_set_page_writeback(page, true)
589
set_page_writeback(struct page * page)590 static inline void set_page_writeback(struct page *page)
591 {
592 test_set_page_writeback(page);
593 }
594
set_page_writeback_keepwrite(struct page * page)595 static inline void set_page_writeback_keepwrite(struct page *page)
596 {
597 test_set_page_writeback_keepwrite(page);
598 }
599
__PAGEFLAG(Head,head,PF_ANY)600 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
601
602 static __always_inline void set_compound_head(struct page *page, struct page *head)
603 {
604 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
605 }
606
clear_compound_head(struct page * page)607 static __always_inline void clear_compound_head(struct page *page)
608 {
609 WRITE_ONCE(page->compound_head, 0);
610 }
611
612 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
ClearPageCompound(struct page * page)613 static inline void ClearPageCompound(struct page *page)
614 {
615 BUG_ON(!PageHead(page));
616 ClearPageHead(page);
617 }
618 #endif
619
620 #define PG_head_mask ((1UL << PG_head))
621
622 #ifdef CONFIG_HUGETLB_PAGE
623 int PageHuge(struct page *page);
624 int PageHeadHuge(struct page *page);
625 bool page_huge_active(struct page *page);
626 #else
627 TESTPAGEFLAG_FALSE(Huge)
TESTPAGEFLAG_FALSE(HeadHuge)628 TESTPAGEFLAG_FALSE(HeadHuge)
629
630 static inline bool page_huge_active(struct page *page)
631 {
632 return 0;
633 }
634 #endif
635
636
637 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
638 /*
639 * PageHuge() only returns true for hugetlbfs pages, but not for
640 * normal or transparent huge pages.
641 *
642 * PageTransHuge() returns true for both transparent huge and
643 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
644 * called only in the core VM paths where hugetlbfs pages can't exist.
645 */
PageTransHuge(struct page * page)646 static inline int PageTransHuge(struct page *page)
647 {
648 VM_BUG_ON_PAGE(PageTail(page), page);
649 return PageHead(page);
650 }
651
652 /*
653 * PageTransCompound returns true for both transparent huge pages
654 * and hugetlbfs pages, so it should only be called when it's known
655 * that hugetlbfs pages aren't involved.
656 */
PageTransCompound(struct page * page)657 static inline int PageTransCompound(struct page *page)
658 {
659 return PageCompound(page);
660 }
661
662 /*
663 * PageTransCompoundMap is the same as PageTransCompound, but it also
664 * guarantees the primary MMU has the entire compound page mapped
665 * through pmd_trans_huge, which in turn guarantees the secondary MMUs
666 * can also map the entire compound page. This allows the secondary
667 * MMUs to call get_user_pages() only once for each compound page and
668 * to immediately map the entire compound page with a single secondary
669 * MMU fault. If there will be a pmd split later, the secondary MMUs
670 * will get an update through the MMU notifier invalidation through
671 * split_huge_pmd().
672 *
673 * Unlike PageTransCompound, this is safe to be called only while
674 * split_huge_pmd() cannot run from under us, like if protected by the
675 * MMU notifier, otherwise it may result in page->_mapcount check false
676 * positives.
677 *
678 * We have to treat page cache THP differently since every subpage of it
679 * would get _mapcount inc'ed once it is PMD mapped. But, it may be PTE
680 * mapped in the current process so comparing subpage's _mapcount to
681 * compound_mapcount to filter out PTE mapped case.
682 */
PageTransCompoundMap(struct page * page)683 static inline int PageTransCompoundMap(struct page *page)
684 {
685 struct page *head;
686
687 if (!PageTransCompound(page))
688 return 0;
689
690 if (PageAnon(page))
691 return atomic_read(&page->_mapcount) < 0;
692
693 head = compound_head(page);
694 /* File THP is PMD mapped and not PTE mapped */
695 return atomic_read(&page->_mapcount) ==
696 atomic_read(compound_mapcount_ptr(head));
697 }
698
699 /*
700 * PageTransTail returns true for both transparent huge pages
701 * and hugetlbfs pages, so it should only be called when it's known
702 * that hugetlbfs pages aren't involved.
703 */
PageTransTail(struct page * page)704 static inline int PageTransTail(struct page *page)
705 {
706 return PageTail(page);
707 }
708
709 /*
710 * PageDoubleMap indicates that the compound page is mapped with PTEs as well
711 * as PMDs.
712 *
713 * This is required for optimization of rmap operations for THP: we can postpone
714 * per small page mapcount accounting (and its overhead from atomic operations)
715 * until the first PMD split.
716 *
717 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
718 * by one. This reference will go away with last compound_mapcount.
719 *
720 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
721 */
PAGEFLAG(DoubleMap,double_map,PF_SECOND)722 PAGEFLAG(DoubleMap, double_map, PF_SECOND)
723 TESTSCFLAG(DoubleMap, double_map, PF_SECOND)
724 #else
725 TESTPAGEFLAG_FALSE(TransHuge)
726 TESTPAGEFLAG_FALSE(TransCompound)
727 TESTPAGEFLAG_FALSE(TransCompoundMap)
728 TESTPAGEFLAG_FALSE(TransTail)
729 PAGEFLAG_FALSE(DoubleMap)
730 TESTSCFLAG_FALSE(DoubleMap)
731 #endif
732
733 /*
734 * For pages that are never mapped to userspace (and aren't PageSlab),
735 * page_type may be used. Because it is initialised to -1, we invert the
736 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
737 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
738 * low bits so that an underflow or overflow of page_mapcount() won't be
739 * mistaken for a page type value.
740 */
741
742 #define PAGE_TYPE_BASE 0xf0000000
743 /* Reserve 0x0000007f to catch underflows of page_mapcount */
744 #define PAGE_MAPCOUNT_RESERVE -128
745 #define PG_buddy 0x00000080
746 #define PG_offline 0x00000100
747 #define PG_kmemcg 0x00000200
748 #define PG_table 0x00000400
749 #define PG_guard 0x00000800
750
751 #define PageType(page, flag) \
752 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
753
754 static inline int page_has_type(struct page *page)
755 {
756 return (int)page->page_type < PAGE_MAPCOUNT_RESERVE;
757 }
758
759 #define PAGE_TYPE_OPS(uname, lname) \
760 static __always_inline int Page##uname(struct page *page) \
761 { \
762 return PageType(page, PG_##lname); \
763 } \
764 static __always_inline void __SetPage##uname(struct page *page) \
765 { \
766 VM_BUG_ON_PAGE(!PageType(page, 0), page); \
767 page->page_type &= ~PG_##lname; \
768 } \
769 static __always_inline void __ClearPage##uname(struct page *page) \
770 { \
771 VM_BUG_ON_PAGE(!Page##uname(page), page); \
772 page->page_type |= PG_##lname; \
773 }
774
775 /*
776 * PageBuddy() indicates that the page is free and in the buddy system
777 * (see mm/page_alloc.c).
778 */
779 PAGE_TYPE_OPS(Buddy, buddy)
780
781 /*
782 * PageOffline() indicates that the page is logically offline although the
783 * containing section is online. (e.g. inflated in a balloon driver or
784 * not onlined when onlining the section).
785 * The content of these pages is effectively stale. Such pages should not
786 * be touched (read/write/dump/save) except by their owner.
787 *
788 * If a driver wants to allow to offline unmovable PageOffline() pages without
789 * putting them back to the buddy, it can do so via the memory notifier by
790 * decrementing the reference count in MEM_GOING_OFFLINE and incrementing the
791 * reference count in MEM_CANCEL_OFFLINE. When offlining, the PageOffline()
792 * pages (now with a reference count of zero) are treated like free pages,
793 * allowing the containing memory block to get offlined. A driver that
794 * relies on this feature is aware that re-onlining the memory block will
795 * require to re-set the pages PageOffline() and not giving them to the
796 * buddy via online_page_callback_t.
797 */
798 PAGE_TYPE_OPS(Offline, offline)
799
800 /*
801 * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on
802 * pages allocated with __GFP_ACCOUNT. It gets cleared on page free.
803 */
804 PAGE_TYPE_OPS(Kmemcg, kmemcg)
805
806 /*
807 * Marks pages in use as page tables.
808 */
809 PAGE_TYPE_OPS(Table, table)
810
811 /*
812 * Marks guardpages used with debug_pagealloc.
813 */
814 PAGE_TYPE_OPS(Guard, guard)
815
816 extern bool is_free_buddy_page(struct page *page);
817
818 __PAGEFLAG(Isolated, isolated, PF_ANY);
819
820 /*
821 * If network-based swap is enabled, sl*b must keep track of whether pages
822 * were allocated from pfmemalloc reserves.
823 */
PageSlabPfmemalloc(struct page * page)824 static inline int PageSlabPfmemalloc(struct page *page)
825 {
826 VM_BUG_ON_PAGE(!PageSlab(page), page);
827 return PageActive(page);
828 }
829
SetPageSlabPfmemalloc(struct page * page)830 static inline void SetPageSlabPfmemalloc(struct page *page)
831 {
832 VM_BUG_ON_PAGE(!PageSlab(page), page);
833 SetPageActive(page);
834 }
835
__ClearPageSlabPfmemalloc(struct page * page)836 static inline void __ClearPageSlabPfmemalloc(struct page *page)
837 {
838 VM_BUG_ON_PAGE(!PageSlab(page), page);
839 __ClearPageActive(page);
840 }
841
ClearPageSlabPfmemalloc(struct page * page)842 static inline void ClearPageSlabPfmemalloc(struct page *page)
843 {
844 VM_BUG_ON_PAGE(!PageSlab(page), page);
845 ClearPageActive(page);
846 }
847
848 #ifdef CONFIG_MMU
849 #define __PG_MLOCKED (1UL << PG_mlocked)
850 #else
851 #define __PG_MLOCKED 0
852 #endif
853
854 /*
855 * Flags checked when a page is freed. Pages being freed should not have
856 * these flags set. It they are, there is a problem.
857 */
858 #ifdef CONFIG_SECURITY_XPM
859 #define __XPM_PAGE_FLAGS (1UL << PG_xpm_readonly | 1UL << PG_xpm_writetainted)
860 #else
861 #define __XPM_PAGE_FLAGS 0
862 #endif
863
864 #define PAGE_FLAGS_CHECK_AT_FREE \
865 (1UL << PG_lru | 1UL << PG_locked | \
866 1UL << PG_private | 1UL << PG_private_2 | \
867 1UL << PG_writeback | 1UL << PG_reserved | \
868 1UL << PG_slab | 1UL << PG_active | \
869 __XPM_PAGE_FLAGS | \
870 1UL << PG_unevictable | __PG_MLOCKED)
871
872 /*
873 * Flags checked when a page is prepped for return by the page allocator.
874 * Pages being prepped should not have these flags set. It they are set,
875 * there has been a kernel bug or struct page corruption.
876 *
877 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
878 * alloc-free cycle to prevent from reusing the page.
879 */
880 #define PAGE_FLAGS_CHECK_AT_PREP \
881 (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
882
883 #define PAGE_FLAGS_PRIVATE \
884 (1UL << PG_private | 1UL << PG_private_2)
885 /**
886 * page_has_private - Determine if page has private stuff
887 * @page: The page to be checked
888 *
889 * Determine if a page has private stuff, indicating that release routines
890 * should be invoked upon it.
891 */
page_has_private(struct page * page)892 static inline int page_has_private(struct page *page)
893 {
894 return !!(page->flags & PAGE_FLAGS_PRIVATE);
895 }
896
897 #undef PF_ANY
898 #undef PF_HEAD
899 #undef PF_ONLY_HEAD
900 #undef PF_NO_TAIL
901 #undef PF_NO_COMPOUND
902 #undef PF_SECOND
903 #endif /* !__GENERATING_BOUNDS_H */
904
905 #endif /* PAGE_FLAGS_H */
906