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1 | /* |
2 | * Macros for manipulating and testing page->flags |
3 | */ |
4 | |
5 | #ifndef PAGE_FLAGS_H |
6 | #define PAGE_FLAGS_H |
7 | |
8 | #include <linux/types.h> |
9 | #include <linux/bug.h> |
10 | #include <linux/mmdebug.h> |
11 | #ifndef __GENERATING_BOUNDS_H |
12 | #include <linux/mm_types.h> |
13 | #include <generated/bounds.h> |
14 | #endif /* !__GENERATING_BOUNDS_H */ |
15 | |
16 | /* |
17 | * Various page->flags bits: |
18 | * |
19 | * PG_reserved is set for special pages, which can never be swapped out. Some |
20 | * of them might not even exist (eg empty_bad_page)... |
21 | * |
22 | * The PG_private bitflag is set on pagecache pages if they contain filesystem |
23 | * specific data (which is normally at page->private). It can be used by |
24 | * private allocations for its own usage. |
25 | * |
26 | * During initiation of disk I/O, PG_locked is set. This bit is set before I/O |
27 | * and cleared when writeback _starts_ or when read _completes_. PG_writeback |
28 | * is set before writeback starts and cleared when it finishes. |
29 | * |
30 | * PG_locked also pins a page in pagecache, and blocks truncation of the file |
31 | * while it is held. |
32 | * |
33 | * page_waitqueue(page) is a wait queue of all tasks waiting for the page |
34 | * to become unlocked. |
35 | * |
36 | * PG_uptodate tells whether the page's contents is valid. When a read |
37 | * completes, the page becomes uptodate, unless a disk I/O error happened. |
38 | * |
39 | * PG_referenced, PG_reclaim are used for page reclaim for anonymous and |
40 | * file-backed pagecache (see mm/vmscan.c). |
41 | * |
42 | * PG_error is set to indicate that an I/O error occurred on this page. |
43 | * |
44 | * PG_arch_1 is an architecture specific page state bit. The generic code |
45 | * guarantees that this bit is cleared for a page when it first is entered into |
46 | * the page cache. |
47 | * |
48 | * PG_highmem pages are not permanently mapped into the kernel virtual address |
49 | * space, they need to be kmapped separately for doing IO on the pages. The |
50 | * struct page (these bits with information) are always mapped into kernel |
51 | * address space... |
52 | * |
53 | * PG_hwpoison indicates that a page got corrupted in hardware and contains |
54 | * data with incorrect ECC bits that triggered a machine check. Accessing is |
55 | * not safe since it may cause another machine check. Don't touch! |
56 | */ |
57 | |
58 | /* |
59 | * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break |
60 | * locked- and dirty-page accounting. |
61 | * |
62 | * The page flags field is split into two parts, the main flags area |
63 | * which extends from the low bits upwards, and the fields area which |
64 | * extends from the high bits downwards. |
65 | * |
66 | * | FIELD | ... | FLAGS | |
67 | * N-1 ^ 0 |
68 | * (NR_PAGEFLAGS) |
69 | * |
70 | * The fields area is reserved for fields mapping zone, node (for NUMA) and |
71 | * SPARSEMEM section (for variants of SPARSEMEM that require section ids like |
72 | * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP). |
73 | */ |
74 | enum pageflags { |
75 | PG_locked, /* Page is locked. Don't touch. */ |
76 | PG_error, |
77 | PG_referenced, |
78 | PG_uptodate, |
79 | PG_dirty, |
80 | PG_lru, |
81 | PG_active, |
82 | PG_slab, |
83 | PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/ |
84 | PG_arch_1, |
85 | PG_reserved, |
86 | PG_private, /* If pagecache, has fs-private data */ |
87 | PG_private_2, /* If pagecache, has fs aux data */ |
88 | PG_writeback, /* Page is under writeback */ |
89 | #ifdef CONFIG_PAGEFLAGS_EXTENDED |
90 | PG_head, /* A head page */ |
91 | PG_tail, /* A tail page */ |
92 | #else |
93 | PG_compound, /* A compound page */ |
94 | #endif |
95 | PG_swapcache, /* Swap page: swp_entry_t in private */ |
96 | PG_mappedtodisk, /* Has blocks allocated on-disk */ |
97 | PG_reclaim, /* To be reclaimed asap */ |
98 | PG_swapbacked, /* Page is backed by RAM/swap */ |
99 | PG_unevictable, /* Page is "unevictable" */ |
100 | #ifdef CONFIG_MMU |
101 | PG_mlocked, /* Page is vma mlocked */ |
102 | #endif |
103 | #ifdef CONFIG_ARCH_USES_PG_UNCACHED |
104 | PG_uncached, /* Page has been mapped as uncached */ |
105 | #endif |
106 | #ifdef CONFIG_MEMORY_FAILURE |
107 | PG_hwpoison, /* hardware poisoned page. Don't touch */ |
108 | #endif |
109 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
110 | PG_compound_lock, |
111 | #endif |
112 | __NR_PAGEFLAGS, |
113 | |
114 | /* Filesystems */ |
115 | PG_checked = PG_owner_priv_1, |
116 | |
117 | /* Two page bits are conscripted by FS-Cache to maintain local caching |
118 | * state. These bits are set on pages belonging to the netfs's inodes |
119 | * when those inodes are being locally cached. |
120 | */ |
121 | PG_fscache = PG_private_2, /* page backed by cache */ |
122 | |
123 | /* XEN */ |
124 | PG_pinned = PG_owner_priv_1, |
125 | PG_savepinned = PG_dirty, |
126 | |
127 | /* SLOB */ |
128 | PG_slob_free = PG_private, |
129 | }; |
130 | |
131 | #ifndef __GENERATING_BOUNDS_H |
132 | |
133 | /* |
134 | * Macros to create function definitions for page flags |
135 | */ |
136 | #define TESTPAGEFLAG(uname, lname) \ |
137 | static inline int Page##uname(const struct page *page) \ |
138 | { return test_bit(PG_##lname, &page->flags); } |
139 | |
140 | #define SETPAGEFLAG(uname, lname) \ |
141 | static inline void SetPage##uname(struct page *page) \ |
142 | { set_bit(PG_##lname, &page->flags); } |
143 | |
144 | #define CLEARPAGEFLAG(uname, lname) \ |
145 | static inline void ClearPage##uname(struct page *page) \ |
146 | { clear_bit(PG_##lname, &page->flags); } |
147 | |
148 | #define __SETPAGEFLAG(uname, lname) \ |
149 | static inline void __SetPage##uname(struct page *page) \ |
150 | { __set_bit(PG_##lname, &page->flags); } |
151 | |
152 | #define __CLEARPAGEFLAG(uname, lname) \ |
153 | static inline void __ClearPage##uname(struct page *page) \ |
154 | { __clear_bit(PG_##lname, &page->flags); } |
155 | |
156 | #define TESTSETFLAG(uname, lname) \ |
157 | static inline int TestSetPage##uname(struct page *page) \ |
158 | { return test_and_set_bit(PG_##lname, &page->flags); } |
159 | |
160 | #define TESTCLEARFLAG(uname, lname) \ |
161 | static inline int TestClearPage##uname(struct page *page) \ |
162 | { return test_and_clear_bit(PG_##lname, &page->flags); } |
163 | |
164 | #define __TESTCLEARFLAG(uname, lname) \ |
165 | static inline int __TestClearPage##uname(struct page *page) \ |
166 | { return __test_and_clear_bit(PG_##lname, &page->flags); } |
167 | |
168 | #define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \ |
169 | SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname) |
170 | |
171 | #define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \ |
172 | __SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname) |
173 | |
174 | #define PAGEFLAG_FALSE(uname) \ |
175 | static inline int Page##uname(const struct page *page) \ |
176 | { return 0; } |
177 | |
178 | #define TESTSCFLAG(uname, lname) \ |
179 | TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname) |
180 | |
181 | #define SETPAGEFLAG_NOOP(uname) \ |
182 | static inline void SetPage##uname(struct page *page) { } |
183 | |
184 | #define CLEARPAGEFLAG_NOOP(uname) \ |
185 | static inline void ClearPage##uname(struct page *page) { } |
186 | |
187 | #define __CLEARPAGEFLAG_NOOP(uname) \ |
188 | static inline void __ClearPage##uname(struct page *page) { } |
189 | |
190 | #define TESTCLEARFLAG_FALSE(uname) \ |
191 | static inline int TestClearPage##uname(struct page *page) { return 0; } |
192 | |
193 | #define __TESTCLEARFLAG_FALSE(uname) \ |
194 | static inline int __TestClearPage##uname(struct page *page) { return 0; } |
195 | |
196 | struct page; /* forward declaration */ |
197 | |
198 | TESTPAGEFLAG(Locked, locked) |
199 | PAGEFLAG(Error, error) TESTCLEARFLAG(Error, error) |
200 | PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced) |
201 | PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty) |
202 | PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru) |
203 | PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active) |
204 | TESTCLEARFLAG(Active, active) |
205 | __PAGEFLAG(Slab, slab) |
206 | PAGEFLAG(Checked, checked) /* Used by some filesystems */ |
207 | PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen */ |
208 | PAGEFLAG(SavePinned, savepinned); /* Xen */ |
209 | PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved) |
210 | PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked) |
211 | |
212 | __PAGEFLAG(SlobFree, slob_free) |
213 | |
214 | /* |
215 | * Private page markings that may be used by the filesystem that owns the page |
216 | * for its own purposes. |
217 | * - PG_private and PG_private_2 cause releasepage() and co to be invoked |
218 | */ |
219 | PAGEFLAG(Private, private) __SETPAGEFLAG(Private, private) |
220 | __CLEARPAGEFLAG(Private, private) |
221 | PAGEFLAG(Private2, private_2) TESTSCFLAG(Private2, private_2) |
222 | PAGEFLAG(OwnerPriv1, owner_priv_1) TESTCLEARFLAG(OwnerPriv1, owner_priv_1) |
223 | |
224 | /* |
225 | * Only test-and-set exist for PG_writeback. The unconditional operators are |
226 | * risky: they bypass page accounting. |
227 | */ |
228 | TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback) |
229 | PAGEFLAG(MappedToDisk, mappedtodisk) |
230 | |
231 | /* PG_readahead is only used for file reads; PG_reclaim is only for writes */ |
232 | PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim) |
233 | PAGEFLAG(Readahead, reclaim) /* Reminder to do async read-ahead */ |
234 | |
235 | #ifdef CONFIG_HIGHMEM |
236 | /* |
237 | * Must use a macro here due to header dependency issues. page_zone() is not |
238 | * available at this point. |
239 | */ |
240 | #define PageHighMem(__p) is_highmem(page_zone(__p)) |
241 | #else |
242 | PAGEFLAG_FALSE(HighMem) |
243 | #endif |
244 | |
245 | #ifdef CONFIG_SWAP |
246 | PAGEFLAG(SwapCache, swapcache) |
247 | #else |
248 | PAGEFLAG_FALSE(SwapCache) |
249 | SETPAGEFLAG_NOOP(SwapCache) CLEARPAGEFLAG_NOOP(SwapCache) |
250 | #endif |
251 | |
252 | PAGEFLAG(Unevictable, unevictable) __CLEARPAGEFLAG(Unevictable, unevictable) |
253 | TESTCLEARFLAG(Unevictable, unevictable) |
254 | |
255 | #ifdef CONFIG_MMU |
256 | PAGEFLAG(Mlocked, mlocked) __CLEARPAGEFLAG(Mlocked, mlocked) |
257 | TESTSCFLAG(Mlocked, mlocked) __TESTCLEARFLAG(Mlocked, mlocked) |
258 | #else |
259 | PAGEFLAG_FALSE(Mlocked) SETPAGEFLAG_NOOP(Mlocked) |
260 | TESTCLEARFLAG_FALSE(Mlocked) __TESTCLEARFLAG_FALSE(Mlocked) |
261 | #endif |
262 | |
263 | #ifdef CONFIG_ARCH_USES_PG_UNCACHED |
264 | PAGEFLAG(Uncached, uncached) |
265 | #else |
266 | PAGEFLAG_FALSE(Uncached) |
267 | #endif |
268 | |
269 | #ifdef CONFIG_MEMORY_FAILURE |
270 | PAGEFLAG(HWPoison, hwpoison) |
271 | TESTSCFLAG(HWPoison, hwpoison) |
272 | #define __PG_HWPOISON (1UL << PG_hwpoison) |
273 | #else |
274 | PAGEFLAG_FALSE(HWPoison) |
275 | #define __PG_HWPOISON 0 |
276 | #endif |
277 | |
278 | u64 stable_page_flags(struct page *page); |
279 | |
280 | static inline int PageUptodate(struct page *page) |
281 | { |
282 | int ret = test_bit(PG_uptodate, &(page)->flags); |
283 | |
284 | /* |
285 | * Must ensure that the data we read out of the page is loaded |
286 | * _after_ we've loaded page->flags to check for PageUptodate. |
287 | * We can skip the barrier if the page is not uptodate, because |
288 | * we wouldn't be reading anything from it. |
289 | * |
290 | * See SetPageUptodate() for the other side of the story. |
291 | */ |
292 | if (ret) |
293 | smp_rmb(); |
294 | |
295 | return ret; |
296 | } |
297 | |
298 | static inline void __SetPageUptodate(struct page *page) |
299 | { |
300 | smp_wmb(); |
301 | __set_bit(PG_uptodate, &(page)->flags); |
302 | } |
303 | |
304 | static inline void SetPageUptodate(struct page *page) |
305 | { |
306 | /* |
307 | * Memory barrier must be issued before setting the PG_uptodate bit, |
308 | * so that all previous stores issued in order to bring the page |
309 | * uptodate are actually visible before PageUptodate becomes true. |
310 | */ |
311 | smp_wmb(); |
312 | set_bit(PG_uptodate, &(page)->flags); |
313 | } |
314 | |
315 | CLEARPAGEFLAG(Uptodate, uptodate) |
316 | |
317 | extern void cancel_dirty_page(struct page *page, unsigned int account_size); |
318 | |
319 | int test_clear_page_writeback(struct page *page); |
320 | int test_set_page_writeback(struct page *page); |
321 | |
322 | static inline void set_page_writeback(struct page *page) |
323 | { |
324 | test_set_page_writeback(page); |
325 | } |
326 | |
327 | #ifdef CONFIG_PAGEFLAGS_EXTENDED |
328 | /* |
329 | * System with lots of page flags available. This allows separate |
330 | * flags for PageHead() and PageTail() checks of compound pages so that bit |
331 | * tests can be used in performance sensitive paths. PageCompound is |
332 | * generally not used in hot code paths. |
333 | */ |
334 | __PAGEFLAG(Head, head) CLEARPAGEFLAG(Head, head) |
335 | __PAGEFLAG(Tail, tail) |
336 | |
337 | static inline int PageCompound(struct page *page) |
338 | { |
339 | return page->flags & ((1L << PG_head) | (1L << PG_tail)); |
340 | |
341 | } |
342 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
343 | static inline void ClearPageCompound(struct page *page) |
344 | { |
345 | BUG_ON(!PageHead(page)); |
346 | ClearPageHead(page); |
347 | } |
348 | #endif |
349 | #else |
350 | /* |
351 | * Reduce page flag use as much as possible by overlapping |
352 | * compound page flags with the flags used for page cache pages. Possible |
353 | * because PageCompound is always set for compound pages and not for |
354 | * pages on the LRU and/or pagecache. |
355 | */ |
356 | TESTPAGEFLAG(Compound, compound) |
357 | __SETPAGEFLAG(Head, compound) __CLEARPAGEFLAG(Head, compound) |
358 | |
359 | /* |
360 | * PG_reclaim is used in combination with PG_compound to mark the |
361 | * head and tail of a compound page. This saves one page flag |
362 | * but makes it impossible to use compound pages for the page cache. |
363 | * The PG_reclaim bit would have to be used for reclaim or readahead |
364 | * if compound pages enter the page cache. |
365 | * |
366 | * PG_compound & PG_reclaim => Tail page |
367 | * PG_compound & ~PG_reclaim => Head page |
368 | */ |
369 | #define PG_head_mask ((1L << PG_compound)) |
370 | #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim)) |
371 | |
372 | static inline int PageHead(struct page *page) |
373 | { |
374 | return ((page->flags & PG_head_tail_mask) == PG_head_mask); |
375 | } |
376 | |
377 | static inline int PageTail(struct page *page) |
378 | { |
379 | return ((page->flags & PG_head_tail_mask) == PG_head_tail_mask); |
380 | } |
381 | |
382 | static inline void __SetPageTail(struct page *page) |
383 | { |
384 | page->flags |= PG_head_tail_mask; |
385 | } |
386 | |
387 | static inline void __ClearPageTail(struct page *page) |
388 | { |
389 | page->flags &= ~PG_head_tail_mask; |
390 | } |
391 | |
392 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
393 | static inline void ClearPageCompound(struct page *page) |
394 | { |
395 | BUG_ON((page->flags & PG_head_tail_mask) != (1 << PG_compound)); |
396 | clear_bit(PG_compound, &page->flags); |
397 | } |
398 | #endif |
399 | |
400 | #endif /* !PAGEFLAGS_EXTENDED */ |
401 | |
402 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
403 | /* |
404 | * PageHuge() only returns true for hugetlbfs pages, but not for |
405 | * normal or transparent huge pages. |
406 | * |
407 | * PageTransHuge() returns true for both transparent huge and |
408 | * hugetlbfs pages, but not normal pages. PageTransHuge() can only be |
409 | * called only in the core VM paths where hugetlbfs pages can't exist. |
410 | */ |
411 | static inline int PageTransHuge(struct page *page) |
412 | { |
413 | VM_BUG_ON(PageTail(page)); |
414 | return PageHead(page); |
415 | } |
416 | |
417 | /* |
418 | * PageTransCompound returns true for both transparent huge pages |
419 | * and hugetlbfs pages, so it should only be called when it's known |
420 | * that hugetlbfs pages aren't involved. |
421 | */ |
422 | static inline int PageTransCompound(struct page *page) |
423 | { |
424 | return PageCompound(page); |
425 | } |
426 | |
427 | /* |
428 | * PageTransTail returns true for both transparent huge pages |
429 | * and hugetlbfs pages, so it should only be called when it's known |
430 | * that hugetlbfs pages aren't involved. |
431 | */ |
432 | static inline int PageTransTail(struct page *page) |
433 | { |
434 | return PageTail(page); |
435 | } |
436 | |
437 | #else |
438 | |
439 | static inline int PageTransHuge(struct page *page) |
440 | { |
441 | return 0; |
442 | } |
443 | |
444 | static inline int PageTransCompound(struct page *page) |
445 | { |
446 | return 0; |
447 | } |
448 | |
449 | static inline int PageTransTail(struct page *page) |
450 | { |
451 | return 0; |
452 | } |
453 | #endif |
454 | |
455 | /* |
456 | * If network-based swap is enabled, sl*b must keep track of whether pages |
457 | * were allocated from pfmemalloc reserves. |
458 | */ |
459 | static inline int PageSlabPfmemalloc(struct page *page) |
460 | { |
461 | VM_BUG_ON(!PageSlab(page)); |
462 | return PageActive(page); |
463 | } |
464 | |
465 | static inline void SetPageSlabPfmemalloc(struct page *page) |
466 | { |
467 | VM_BUG_ON(!PageSlab(page)); |
468 | SetPageActive(page); |
469 | } |
470 | |
471 | static inline void __ClearPageSlabPfmemalloc(struct page *page) |
472 | { |
473 | VM_BUG_ON(!PageSlab(page)); |
474 | __ClearPageActive(page); |
475 | } |
476 | |
477 | static inline void ClearPageSlabPfmemalloc(struct page *page) |
478 | { |
479 | VM_BUG_ON(!PageSlab(page)); |
480 | ClearPageActive(page); |
481 | } |
482 | |
483 | #ifdef CONFIG_MMU |
484 | #define __PG_MLOCKED (1 << PG_mlocked) |
485 | #else |
486 | #define __PG_MLOCKED 0 |
487 | #endif |
488 | |
489 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
490 | #define __PG_COMPOUND_LOCK (1 << PG_compound_lock) |
491 | #else |
492 | #define __PG_COMPOUND_LOCK 0 |
493 | #endif |
494 | |
495 | /* |
496 | * Flags checked when a page is freed. Pages being freed should not have |
497 | * these flags set. It they are, there is a problem. |
498 | */ |
499 | #define PAGE_FLAGS_CHECK_AT_FREE \ |
500 | (1 << PG_lru | 1 << PG_locked | \ |
501 | 1 << PG_private | 1 << PG_private_2 | \ |
502 | 1 << PG_writeback | 1 << PG_reserved | \ |
503 | 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \ |
504 | 1 << PG_unevictable | __PG_MLOCKED | __PG_HWPOISON | \ |
505 | __PG_COMPOUND_LOCK) |
506 | |
507 | /* |
508 | * Flags checked when a page is prepped for return by the page allocator. |
509 | * Pages being prepped should not have any flags set. It they are set, |
510 | * there has been a kernel bug or struct page corruption. |
511 | */ |
512 | #define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1) |
513 | |
514 | #define PAGE_FLAGS_PRIVATE \ |
515 | (1 << PG_private | 1 << PG_private_2) |
516 | /** |
517 | * page_has_private - Determine if page has private stuff |
518 | * @page: The page to be checked |
519 | * |
520 | * Determine if a page has private stuff, indicating that release routines |
521 | * should be invoked upon it. |
522 | */ |
523 | static inline int page_has_private(struct page *page) |
524 | { |
525 | return !!(page->flags & PAGE_FLAGS_PRIVATE); |
526 | } |
527 | |
528 | #endif /* !__GENERATING_BOUNDS_H */ |
529 | |
530 | #endif /* PAGE_FLAGS_H */ |
531 |
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