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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 | #ifndef __GENERATING_BOUNDS_H |
10 | #include <linux/mm_types.h> |
11 | #include <generated/bounds.h> |
12 | #endif /* !__GENERATING_BOUNDS_H */ |
13 | |
14 | /* |
15 | * Various page->flags bits: |
16 | * |
17 | * PG_reserved is set for special pages, which can never be swapped out. Some |
18 | * of them might not even exist (eg empty_bad_page)... |
19 | * |
20 | * The PG_private bitflag is set on pagecache pages if they contain filesystem |
21 | * specific data (which is normally at page->private). It can be used by |
22 | * private allocations for its own usage. |
23 | * |
24 | * During initiation of disk I/O, PG_locked is set. This bit is set before I/O |
25 | * and cleared when writeback _starts_ or when read _completes_. PG_writeback |
26 | * is set before writeback starts and cleared when it finishes. |
27 | * |
28 | * PG_locked also pins a page in pagecache, and blocks truncation of the file |
29 | * while it is held. |
30 | * |
31 | * page_waitqueue(page) is a wait queue of all tasks waiting for the page |
32 | * to become unlocked. |
33 | * |
34 | * PG_uptodate tells whether the page's contents is valid. When a read |
35 | * completes, the page becomes uptodate, unless a disk I/O error happened. |
36 | * |
37 | * PG_referenced, PG_reclaim are used for page reclaim for anonymous and |
38 | * file-backed pagecache (see mm/vmscan.c). |
39 | * |
40 | * PG_error is set to indicate that an I/O error occurred on this page. |
41 | * |
42 | * PG_arch_1 is an architecture specific page state bit. The generic code |
43 | * guarantees that this bit is cleared for a page when it first is entered into |
44 | * the page cache. |
45 | * |
46 | * PG_highmem pages are not permanently mapped into the kernel virtual address |
47 | * space, they need to be kmapped separately for doing IO on the pages. The |
48 | * struct page (these bits with information) are always mapped into kernel |
49 | * address space... |
50 | * |
51 | * PG_buddy is set to indicate that the page is free and in the buddy system |
52 | * (see mm/page_alloc.c). |
53 | * |
54 | * PG_hwpoison indicates that a page got corrupted in hardware and contains |
55 | * data with incorrect ECC bits that triggered a machine check. Accessing is |
56 | * not safe since it may cause another machine check. Don't touch! |
57 | */ |
58 | |
59 | /* |
60 | * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break |
61 | * locked- and dirty-page accounting. |
62 | * |
63 | * The page flags field is split into two parts, the main flags area |
64 | * which extends from the low bits upwards, and the fields area which |
65 | * extends from the high bits downwards. |
66 | * |
67 | * | FIELD | ... | FLAGS | |
68 | * N-1 ^ 0 |
69 | * (NR_PAGEFLAGS) |
70 | * |
71 | * The fields area is reserved for fields mapping zone, node (for NUMA) and |
72 | * SPARSEMEM section (for variants of SPARSEMEM that require section ids like |
73 | * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP). |
74 | */ |
75 | enum pageflags { |
76 | PG_locked, /* Page is locked. Don't touch. */ |
77 | PG_error, |
78 | PG_referenced, |
79 | PG_uptodate, |
80 | PG_dirty, |
81 | PG_lru, |
82 | PG_active, |
83 | PG_slab, |
84 | PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/ |
85 | PG_arch_1, |
86 | PG_reserved, |
87 | PG_private, /* If pagecache, has fs-private data */ |
88 | PG_private_2, /* If pagecache, has fs aux data */ |
89 | PG_writeback, /* Page is under writeback */ |
90 | #ifdef CONFIG_PAGEFLAGS_EXTENDED |
91 | PG_head, /* A head page */ |
92 | PG_tail, /* A tail page */ |
93 | #else |
94 | PG_compound, /* A compound page */ |
95 | #endif |
96 | PG_swapcache, /* Swap page: swp_entry_t in private */ |
97 | PG_mappedtodisk, /* Has blocks allocated on-disk */ |
98 | PG_reclaim, /* To be reclaimed asap */ |
99 | PG_buddy, /* Page is free, on buddy lists */ |
100 | PG_swapbacked, /* Page is backed by RAM/swap */ |
101 | PG_unevictable, /* Page is "unevictable" */ |
102 | #ifdef CONFIG_MMU |
103 | PG_mlocked, /* Page is vma mlocked */ |
104 | #endif |
105 | #ifdef CONFIG_ARCH_USES_PG_UNCACHED |
106 | PG_uncached, /* Page has been mapped as uncached */ |
107 | #endif |
108 | #ifdef CONFIG_MEMORY_FAILURE |
109 | PG_hwpoison, /* hardware poisoned page. Don't touch */ |
110 | #endif |
111 | __NR_PAGEFLAGS, |
112 | |
113 | /* Filesystems */ |
114 | PG_checked = PG_owner_priv_1, |
115 | |
116 | /* Two page bits are conscripted by FS-Cache to maintain local caching |
117 | * state. These bits are set on pages belonging to the netfs's inodes |
118 | * when those inodes are being locally cached. |
119 | */ |
120 | PG_fscache = PG_private_2, /* page backed by cache */ |
121 | |
122 | /* XEN */ |
123 | PG_pinned = PG_owner_priv_1, |
124 | PG_savepinned = PG_dirty, |
125 | |
126 | /* SLOB */ |
127 | PG_slob_free = PG_private, |
128 | |
129 | /* SLUB */ |
130 | PG_slub_frozen = PG_active, |
131 | PG_slub_debug = PG_error, |
132 | }; |
133 | |
134 | #ifndef __GENERATING_BOUNDS_H |
135 | |
136 | /* |
137 | * Macros to create function definitions for page flags |
138 | */ |
139 | #define TESTPAGEFLAG(uname, lname) \ |
140 | static inline int Page##uname(struct page *page) \ |
141 | { return test_bit(PG_##lname, &page->flags); } |
142 | |
143 | #define SETPAGEFLAG(uname, lname) \ |
144 | static inline void SetPage##uname(struct page *page) \ |
145 | { set_bit(PG_##lname, &page->flags); } |
146 | |
147 | #define CLEARPAGEFLAG(uname, lname) \ |
148 | static inline void ClearPage##uname(struct page *page) \ |
149 | { clear_bit(PG_##lname, &page->flags); } |
150 | |
151 | #define __SETPAGEFLAG(uname, lname) \ |
152 | static inline void __SetPage##uname(struct page *page) \ |
153 | { __set_bit(PG_##lname, &page->flags); } |
154 | |
155 | #define __CLEARPAGEFLAG(uname, lname) \ |
156 | static inline void __ClearPage##uname(struct page *page) \ |
157 | { __clear_bit(PG_##lname, &page->flags); } |
158 | |
159 | #define TESTSETFLAG(uname, lname) \ |
160 | static inline int TestSetPage##uname(struct page *page) \ |
161 | { return test_and_set_bit(PG_##lname, &page->flags); } |
162 | |
163 | #define TESTCLEARFLAG(uname, lname) \ |
164 | static inline int TestClearPage##uname(struct page *page) \ |
165 | { return test_and_clear_bit(PG_##lname, &page->flags); } |
166 | |
167 | #define __TESTCLEARFLAG(uname, lname) \ |
168 | static inline int __TestClearPage##uname(struct page *page) \ |
169 | { return __test_and_clear_bit(PG_##lname, &page->flags); } |
170 | |
171 | #define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \ |
172 | SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname) |
173 | |
174 | #define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \ |
175 | __SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname) |
176 | |
177 | #define PAGEFLAG_FALSE(uname) \ |
178 | static inline int Page##uname(struct page *page) \ |
179 | { return 0; } |
180 | |
181 | #define TESTSCFLAG(uname, lname) \ |
182 | TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname) |
183 | |
184 | #define SETPAGEFLAG_NOOP(uname) \ |
185 | static inline void SetPage##uname(struct page *page) { } |
186 | |
187 | #define CLEARPAGEFLAG_NOOP(uname) \ |
188 | static inline void ClearPage##uname(struct page *page) { } |
189 | |
190 | #define __CLEARPAGEFLAG_NOOP(uname) \ |
191 | static inline void __ClearPage##uname(struct page *page) { } |
192 | |
193 | #define TESTCLEARFLAG_FALSE(uname) \ |
194 | static inline int TestClearPage##uname(struct page *page) { return 0; } |
195 | |
196 | #define __TESTCLEARFLAG_FALSE(uname) \ |
197 | static inline int __TestClearPage##uname(struct page *page) { return 0; } |
198 | |
199 | struct page; /* forward declaration */ |
200 | |
201 | TESTPAGEFLAG(Locked, locked) TESTSETFLAG(Locked, locked) |
202 | PAGEFLAG(Error, error) |
203 | PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced) |
204 | PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty) |
205 | PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru) |
206 | PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active) |
207 | TESTCLEARFLAG(Active, active) |
208 | __PAGEFLAG(Slab, slab) |
209 | PAGEFLAG(Checked, checked) /* Used by some filesystems */ |
210 | PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen */ |
211 | PAGEFLAG(SavePinned, savepinned); /* Xen */ |
212 | PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved) |
213 | PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked) |
214 | |
215 | __PAGEFLAG(SlobFree, slob_free) |
216 | |
217 | __PAGEFLAG(SlubFrozen, slub_frozen) |
218 | __PAGEFLAG(SlubDebug, slub_debug) |
219 | |
220 | /* |
221 | * Private page markings that may be used by the filesystem that owns the page |
222 | * for its own purposes. |
223 | * - PG_private and PG_private_2 cause releasepage() and co to be invoked |
224 | */ |
225 | PAGEFLAG(Private, private) __SETPAGEFLAG(Private, private) |
226 | __CLEARPAGEFLAG(Private, private) |
227 | PAGEFLAG(Private2, private_2) TESTSCFLAG(Private2, private_2) |
228 | PAGEFLAG(OwnerPriv1, owner_priv_1) TESTCLEARFLAG(OwnerPriv1, owner_priv_1) |
229 | |
230 | /* |
231 | * Only test-and-set exist for PG_writeback. The unconditional operators are |
232 | * risky: they bypass page accounting. |
233 | */ |
234 | TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback) |
235 | __PAGEFLAG(Buddy, buddy) |
236 | PAGEFLAG(MappedToDisk, mappedtodisk) |
237 | |
238 | /* PG_readahead is only used for file reads; PG_reclaim is only for writes */ |
239 | PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim) |
240 | PAGEFLAG(Readahead, reclaim) /* Reminder to do async read-ahead */ |
241 | |
242 | #ifdef CONFIG_HIGHMEM |
243 | /* |
244 | * Must use a macro here due to header dependency issues. page_zone() is not |
245 | * available at this point. |
246 | */ |
247 | #define PageHighMem(__p) is_highmem(page_zone(__p)) |
248 | #else |
249 | PAGEFLAG_FALSE(HighMem) |
250 | #endif |
251 | |
252 | #ifdef CONFIG_SWAP |
253 | PAGEFLAG(SwapCache, swapcache) |
254 | #else |
255 | PAGEFLAG_FALSE(SwapCache) |
256 | SETPAGEFLAG_NOOP(SwapCache) CLEARPAGEFLAG_NOOP(SwapCache) |
257 | #endif |
258 | |
259 | PAGEFLAG(Unevictable, unevictable) __CLEARPAGEFLAG(Unevictable, unevictable) |
260 | TESTCLEARFLAG(Unevictable, unevictable) |
261 | |
262 | #ifdef CONFIG_MMU |
263 | PAGEFLAG(Mlocked, mlocked) __CLEARPAGEFLAG(Mlocked, mlocked) |
264 | TESTSCFLAG(Mlocked, mlocked) __TESTCLEARFLAG(Mlocked, mlocked) |
265 | #else |
266 | PAGEFLAG_FALSE(Mlocked) SETPAGEFLAG_NOOP(Mlocked) |
267 | TESTCLEARFLAG_FALSE(Mlocked) __TESTCLEARFLAG_FALSE(Mlocked) |
268 | #endif |
269 | |
270 | #ifdef CONFIG_ARCH_USES_PG_UNCACHED |
271 | PAGEFLAG(Uncached, uncached) |
272 | #else |
273 | PAGEFLAG_FALSE(Uncached) |
274 | #endif |
275 | |
276 | #ifdef CONFIG_MEMORY_FAILURE |
277 | PAGEFLAG(HWPoison, hwpoison) |
278 | TESTSCFLAG(HWPoison, hwpoison) |
279 | #define __PG_HWPOISON (1UL << PG_hwpoison) |
280 | #else |
281 | PAGEFLAG_FALSE(HWPoison) |
282 | #define __PG_HWPOISON 0 |
283 | #endif |
284 | |
285 | u64 stable_page_flags(struct page *page); |
286 | |
287 | static inline int PageUptodate(struct page *page) |
288 | { |
289 | int ret = test_bit(PG_uptodate, &(page)->flags); |
290 | |
291 | /* |
292 | * Must ensure that the data we read out of the page is loaded |
293 | * _after_ we've loaded page->flags to check for PageUptodate. |
294 | * We can skip the barrier if the page is not uptodate, because |
295 | * we wouldn't be reading anything from it. |
296 | * |
297 | * See SetPageUptodate() for the other side of the story. |
298 | */ |
299 | if (ret) |
300 | smp_rmb(); |
301 | |
302 | return ret; |
303 | } |
304 | |
305 | static inline void __SetPageUptodate(struct page *page) |
306 | { |
307 | smp_wmb(); |
308 | __set_bit(PG_uptodate, &(page)->flags); |
309 | } |
310 | |
311 | static inline void SetPageUptodate(struct page *page) |
312 | { |
313 | #ifdef CONFIG_S390 |
314 | if (!test_and_set_bit(PG_uptodate, &page->flags)) |
315 | page_clear_dirty(page); |
316 | #else |
317 | /* |
318 | * Memory barrier must be issued before setting the PG_uptodate bit, |
319 | * so that all previous stores issued in order to bring the page |
320 | * uptodate are actually visible before PageUptodate becomes true. |
321 | * |
322 | * s390 doesn't need an explicit smp_wmb here because the test and |
323 | * set bit already provides full barriers. |
324 | */ |
325 | smp_wmb(); |
326 | set_bit(PG_uptodate, &(page)->flags); |
327 | #endif |
328 | } |
329 | |
330 | CLEARPAGEFLAG(Uptodate, uptodate) |
331 | |
332 | extern void cancel_dirty_page(struct page *page, unsigned int account_size); |
333 | |
334 | int test_clear_page_writeback(struct page *page); |
335 | int test_set_page_writeback(struct page *page); |
336 | |
337 | static inline void set_page_writeback(struct page *page) |
338 | { |
339 | test_set_page_writeback(page); |
340 | } |
341 | |
342 | #ifdef CONFIG_PAGEFLAGS_EXTENDED |
343 | /* |
344 | * System with lots of page flags available. This allows separate |
345 | * flags for PageHead() and PageTail() checks of compound pages so that bit |
346 | * tests can be used in performance sensitive paths. PageCompound is |
347 | * generally not used in hot code paths. |
348 | */ |
349 | __PAGEFLAG(Head, head) |
350 | __PAGEFLAG(Tail, tail) |
351 | |
352 | static inline int PageCompound(struct page *page) |
353 | { |
354 | return page->flags & ((1L << PG_head) | (1L << PG_tail)); |
355 | |
356 | } |
357 | #else |
358 | /* |
359 | * Reduce page flag use as much as possible by overlapping |
360 | * compound page flags with the flags used for page cache pages. Possible |
361 | * because PageCompound is always set for compound pages and not for |
362 | * pages on the LRU and/or pagecache. |
363 | */ |
364 | TESTPAGEFLAG(Compound, compound) |
365 | __PAGEFLAG(Head, compound) |
366 | |
367 | /* |
368 | * PG_reclaim is used in combination with PG_compound to mark the |
369 | * head and tail of a compound page. This saves one page flag |
370 | * but makes it impossible to use compound pages for the page cache. |
371 | * The PG_reclaim bit would have to be used for reclaim or readahead |
372 | * if compound pages enter the page cache. |
373 | * |
374 | * PG_compound & PG_reclaim => Tail page |
375 | * PG_compound & ~PG_reclaim => Head page |
376 | */ |
377 | #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim)) |
378 | |
379 | static inline int PageTail(struct page *page) |
380 | { |
381 | return ((page->flags & PG_head_tail_mask) == PG_head_tail_mask); |
382 | } |
383 | |
384 | static inline void __SetPageTail(struct page *page) |
385 | { |
386 | page->flags |= PG_head_tail_mask; |
387 | } |
388 | |
389 | static inline void __ClearPageTail(struct page *page) |
390 | { |
391 | page->flags &= ~PG_head_tail_mask; |
392 | } |
393 | |
394 | #endif /* !PAGEFLAGS_EXTENDED */ |
395 | |
396 | #ifdef CONFIG_MMU |
397 | #define __PG_MLOCKED (1 << PG_mlocked) |
398 | #else |
399 | #define __PG_MLOCKED 0 |
400 | #endif |
401 | |
402 | /* |
403 | * Flags checked when a page is freed. Pages being freed should not have |
404 | * these flags set. It they are, there is a problem. |
405 | */ |
406 | #define PAGE_FLAGS_CHECK_AT_FREE \ |
407 | (1 << PG_lru | 1 << PG_locked | \ |
408 | 1 << PG_private | 1 << PG_private_2 | \ |
409 | 1 << PG_buddy | 1 << PG_writeback | 1 << PG_reserved | \ |
410 | 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \ |
411 | 1 << PG_unevictable | __PG_MLOCKED | __PG_HWPOISON) |
412 | |
413 | /* |
414 | * Flags checked when a page is prepped for return by the page allocator. |
415 | * Pages being prepped should not have any flags set. It they are set, |
416 | * there has been a kernel bug or struct page corruption. |
417 | */ |
418 | #define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1) |
419 | |
420 | #define PAGE_FLAGS_PRIVATE \ |
421 | (1 << PG_private | 1 << PG_private_2) |
422 | /** |
423 | * page_has_private - Determine if page has private stuff |
424 | * @page: The page to be checked |
425 | * |
426 | * Determine if a page has private stuff, indicating that release routines |
427 | * should be invoked upon it. |
428 | */ |
429 | static inline int page_has_private(struct page *page) |
430 | { |
431 | return !!(page->flags & PAGE_FLAGS_PRIVATE); |
432 | } |
433 | |
434 | #endif /* !__GENERATING_BOUNDS_H */ |
435 | |
436 | #endif /* PAGE_FLAGS_H */ |
437 |
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