Line data Source code
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)
202 592 : PAGEFLAG(Error, error)
203 74 : PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
204 148 : 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 1406 : PAGEFLAG(Checked, checked) /* Used by some filesystems */
210 592 : PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen */
211 74 : 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 */
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