2 * Macros for manipulating and testing page->flags
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 */
15 * Various page->flags bits:
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)...
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.
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.
28 * PG_locked also pins a page in pagecache, and blocks truncation of the file
31 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
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.
37 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
38 * file-backed pagecache (see mm/vmscan.c).
40 * PG_error is set to indicate that an I/O error occurred on this page.
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
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
51 * PG_buddy is set to indicate that the page is free and in the buddy system
52 * (see mm/page_alloc.c).
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!
60 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
61 * locked- and dirty-page accounting.
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.
67 * | FIELD | ... | FLAGS |
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).
76 PG_locked
, /* Page is locked. Don't touch. */
84 PG_owner_priv_1
, /* Owner use. If pagecache, fs may use*/
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 */
94 PG_compound
, /* A compound page */
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" */
103 PG_mlocked
, /* Page is vma mlocked */
105 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
106 PG_uncached
, /* Page has been mapped as uncached */
108 #ifdef CONFIG_MEMORY_FAILURE
109 PG_hwpoison
, /* hardware poisoned page. Don't touch */
111 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
117 PG_checked
= PG_owner_priv_1
,
119 /* Two page bits are conscripted by FS-Cache to maintain local caching
120 * state. These bits are set on pages belonging to the netfs's inodes
121 * when those inodes are being locally cached.
123 PG_fscache
= PG_private_2
, /* page backed by cache */
126 PG_pinned
= PG_owner_priv_1
,
127 PG_savepinned
= PG_dirty
,
130 PG_slob_free
= PG_private
,
133 PG_slub_frozen
= PG_active
,
136 #ifndef __GENERATING_BOUNDS_H
139 * Macros to create function definitions for page flags
141 #define TESTPAGEFLAG(uname, lname) \
142 static inline int Page##uname(struct page *page) \
143 { return test_bit(PG_##lname, &page->flags); }
145 #define SETPAGEFLAG(uname, lname) \
146 static inline void SetPage##uname(struct page *page) \
147 { set_bit(PG_##lname, &page->flags); }
149 #define CLEARPAGEFLAG(uname, lname) \
150 static inline void ClearPage##uname(struct page *page) \
151 { clear_bit(PG_##lname, &page->flags); }
153 #define __SETPAGEFLAG(uname, lname) \
154 static inline void __SetPage##uname(struct page *page) \
155 { __set_bit(PG_##lname, &page->flags); }
157 #define __CLEARPAGEFLAG(uname, lname) \
158 static inline void __ClearPage##uname(struct page *page) \
159 { __clear_bit(PG_##lname, &page->flags); }
161 #define TESTSETFLAG(uname, lname) \
162 static inline int TestSetPage##uname(struct page *page) \
163 { return test_and_set_bit(PG_##lname, &page->flags); }
165 #define TESTCLEARFLAG(uname, lname) \
166 static inline int TestClearPage##uname(struct page *page) \
167 { return test_and_clear_bit(PG_##lname, &page->flags); }
169 #define __TESTCLEARFLAG(uname, lname) \
170 static inline int __TestClearPage##uname(struct page *page) \
171 { return __test_and_clear_bit(PG_##lname, &page->flags); }
173 #define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
174 SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname)
176 #define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
177 __SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname)
179 #define PAGEFLAG_FALSE(uname) \
180 static inline int Page##uname(struct page *page) \
183 #define TESTSCFLAG(uname, lname) \
184 TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)
186 #define SETPAGEFLAG_NOOP(uname) \
187 static inline void SetPage##uname(struct page *page) { }
189 #define CLEARPAGEFLAG_NOOP(uname) \
190 static inline void ClearPage##uname(struct page *page) { }
192 #define __CLEARPAGEFLAG_NOOP(uname) \
193 static inline void __ClearPage##uname(struct page *page) { }
195 #define TESTCLEARFLAG_FALSE(uname) \
196 static inline int TestClearPage##uname(struct page *page) { return 0; }
198 #define __TESTCLEARFLAG_FALSE(uname) \
199 static inline int __TestClearPage##uname(struct page *page) { return 0; }
201 struct page
; /* forward declaration */
203 TESTPAGEFLAG(Locked
, locked
) TESTSETFLAG(Locked
, locked
)
204 PAGEFLAG(Error
, error
) TESTCLEARFLAG(Error
, error
)
205 PAGEFLAG(Referenced
, referenced
) TESTCLEARFLAG(Referenced
, referenced
)
206 PAGEFLAG(Dirty
, dirty
) TESTSCFLAG(Dirty
, dirty
) __CLEARPAGEFLAG(Dirty
, dirty
)
207 PAGEFLAG(LRU
, lru
) __CLEARPAGEFLAG(LRU
, lru
)
208 PAGEFLAG(Active
, active
) __CLEARPAGEFLAG(Active
, active
)
209 TESTCLEARFLAG(Active
, active
)
210 __PAGEFLAG(Slab
, slab
)
211 PAGEFLAG(Checked
, checked
) /* Used by some filesystems */
212 PAGEFLAG(Pinned
, pinned
) TESTSCFLAG(Pinned
, pinned
) /* Xen */
213 PAGEFLAG(SavePinned
, savepinned
); /* Xen */
214 PAGEFLAG(Reserved
, reserved
) __CLEARPAGEFLAG(Reserved
, reserved
)
215 PAGEFLAG(SwapBacked
, swapbacked
) __CLEARPAGEFLAG(SwapBacked
, swapbacked
)
217 __PAGEFLAG(SlobFree
, slob_free
)
219 __PAGEFLAG(SlubFrozen
, slub_frozen
)
222 * Private page markings that may be used by the filesystem that owns the page
223 * for its own purposes.
224 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
226 PAGEFLAG(Private
, private) __SETPAGEFLAG(Private
, private)
227 __CLEARPAGEFLAG(Private
, private)
228 PAGEFLAG(Private2
, private_2
) TESTSCFLAG(Private2
, private_2
)
229 PAGEFLAG(OwnerPriv1
, owner_priv_1
) TESTCLEARFLAG(OwnerPriv1
, owner_priv_1
)
232 * Only test-and-set exist for PG_writeback. The unconditional operators are
233 * risky: they bypass page accounting.
235 TESTPAGEFLAG(Writeback
, writeback
) TESTSCFLAG(Writeback
, writeback
)
236 __PAGEFLAG(Buddy
, buddy
)
237 PAGEFLAG(MappedToDisk
, mappedtodisk
)
239 /* PG_readahead is only used for file reads; PG_reclaim is only for writes */
240 PAGEFLAG(Reclaim
, reclaim
) TESTCLEARFLAG(Reclaim
, reclaim
)
241 PAGEFLAG(Readahead
, reclaim
) /* Reminder to do async read-ahead */
243 #ifdef CONFIG_HIGHMEM
245 * Must use a macro here due to header dependency issues. page_zone() is not
246 * available at this point.
248 #define PageHighMem(__p) is_highmem(page_zone(__p))
250 PAGEFLAG_FALSE(HighMem
)
254 PAGEFLAG(SwapCache
, swapcache
)
256 PAGEFLAG_FALSE(SwapCache
)
257 SETPAGEFLAG_NOOP(SwapCache
) CLEARPAGEFLAG_NOOP(SwapCache
)
260 PAGEFLAG(Unevictable
, unevictable
) __CLEARPAGEFLAG(Unevictable
, unevictable
)
261 TESTCLEARFLAG(Unevictable
, unevictable
)
264 PAGEFLAG(Mlocked
, mlocked
) __CLEARPAGEFLAG(Mlocked
, mlocked
)
265 TESTSCFLAG(Mlocked
, mlocked
) __TESTCLEARFLAG(Mlocked
, mlocked
)
267 PAGEFLAG_FALSE(Mlocked
) SETPAGEFLAG_NOOP(Mlocked
)
268 TESTCLEARFLAG_FALSE(Mlocked
) __TESTCLEARFLAG_FALSE(Mlocked
)
271 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
272 PAGEFLAG(Uncached
, uncached
)
274 PAGEFLAG_FALSE(Uncached
)
277 #ifdef CONFIG_MEMORY_FAILURE
278 PAGEFLAG(HWPoison
, hwpoison
)
279 TESTSCFLAG(HWPoison
, hwpoison
)
280 #define __PG_HWPOISON (1UL << PG_hwpoison)
282 PAGEFLAG_FALSE(HWPoison
)
283 #define __PG_HWPOISON 0
286 u64
stable_page_flags(struct page
*page
);
288 static inline int PageUptodate(struct page
*page
)
290 int ret
= test_bit(PG_uptodate
, &(page
)->flags
);
293 * Must ensure that the data we read out of the page is loaded
294 * _after_ we've loaded page->flags to check for PageUptodate.
295 * We can skip the barrier if the page is not uptodate, because
296 * we wouldn't be reading anything from it.
298 * See SetPageUptodate() for the other side of the story.
306 static inline void __SetPageUptodate(struct page
*page
)
309 __set_bit(PG_uptodate
, &(page
)->flags
);
312 static inline void SetPageUptodate(struct page
*page
)
315 if (!test_and_set_bit(PG_uptodate
, &page
->flags
))
316 page_clear_dirty(page
, 0);
319 * Memory barrier must be issued before setting the PG_uptodate bit,
320 * so that all previous stores issued in order to bring the page
321 * uptodate are actually visible before PageUptodate becomes true.
323 * s390 doesn't need an explicit smp_wmb here because the test and
324 * set bit already provides full barriers.
327 set_bit(PG_uptodate
, &(page
)->flags
);
331 CLEARPAGEFLAG(Uptodate
, uptodate
)
333 extern void cancel_dirty_page(struct page
*page
, unsigned int account_size
);
335 int test_clear_page_writeback(struct page
*page
);
336 int test_set_page_writeback(struct page
*page
);
338 static inline void set_page_writeback(struct page
*page
)
340 test_set_page_writeback(page
);
343 #ifdef CONFIG_PAGEFLAGS_EXTENDED
345 * System with lots of page flags available. This allows separate
346 * flags for PageHead() and PageTail() checks of compound pages so that bit
347 * tests can be used in performance sensitive paths. PageCompound is
348 * generally not used in hot code paths.
350 __PAGEFLAG(Head
, head
) CLEARPAGEFLAG(Head
, head
)
351 __PAGEFLAG(Tail
, tail
)
353 static inline int PageCompound(struct page
*page
)
355 return page
->flags
& ((1L << PG_head
) | (1L << PG_tail
));
358 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
359 static inline void ClearPageCompound(struct page
*page
)
361 BUG_ON(!PageHead(page
));
367 * Reduce page flag use as much as possible by overlapping
368 * compound page flags with the flags used for page cache pages. Possible
369 * because PageCompound is always set for compound pages and not for
370 * pages on the LRU and/or pagecache.
372 TESTPAGEFLAG(Compound
, compound
)
373 __PAGEFLAG(Head
, compound
)
376 * PG_reclaim is used in combination with PG_compound to mark the
377 * head and tail of a compound page. This saves one page flag
378 * but makes it impossible to use compound pages for the page cache.
379 * The PG_reclaim bit would have to be used for reclaim or readahead
380 * if compound pages enter the page cache.
382 * PG_compound & PG_reclaim => Tail page
383 * PG_compound & ~PG_reclaim => Head page
385 #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
387 static inline int PageTail(struct page
*page
)
389 return ((page
->flags
& PG_head_tail_mask
) == PG_head_tail_mask
);
392 static inline void __SetPageTail(struct page
*page
)
394 page
->flags
|= PG_head_tail_mask
;
397 static inline void __ClearPageTail(struct page
*page
)
399 page
->flags
&= ~PG_head_tail_mask
;
402 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
403 static inline void ClearPageCompound(struct page
*page
)
405 BUG_ON((page
->flags
& PG_head_tail_mask
) != (1 << PG_compound
));
406 clear_bit(PG_compound
, &page
->flags
);
410 #endif /* !PAGEFLAGS_EXTENDED */
413 #define __PG_MLOCKED (1 << PG_mlocked)
415 #define __PG_MLOCKED 0
418 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
419 #define __PG_COMPOUND_LOCK (1 << PG_compound_lock)
421 #define __PG_COMPOUND_LOCK 0
425 * Flags checked when a page is freed. Pages being freed should not have
426 * these flags set. It they are, there is a problem.
428 #define PAGE_FLAGS_CHECK_AT_FREE \
429 (1 << PG_lru | 1 << PG_locked | \
430 1 << PG_private | 1 << PG_private_2 | \
431 1 << PG_buddy | 1 << PG_writeback | 1 << PG_reserved | \
432 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
433 1 << PG_unevictable | __PG_MLOCKED | __PG_HWPOISON | \
437 * Flags checked when a page is prepped for return by the page allocator.
438 * Pages being prepped should not have any flags set. It they are set,
439 * there has been a kernel bug or struct page corruption.
441 #define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1)
443 #define PAGE_FLAGS_PRIVATE \
444 (1 << PG_private | 1 << PG_private_2)
446 * page_has_private - Determine if page has private stuff
447 * @page: The page to be checked
449 * Determine if a page has private stuff, indicating that release routines
450 * should be invoked upon it.
452 static inline int page_has_private(struct page
*page
)
454 return !!(page
->flags
& PAGE_FLAGS_PRIVATE
);
457 #endif /* !__GENERATING_BOUNDS_H */
459 #endif /* PAGE_FLAGS_H */