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 <linux/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).
57 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
58 * locked- and dirty-page accounting.
60 * The page flags field is split into two parts, the main flags area
61 * which extends from the low bits upwards, and the fields area which
62 * extends from the high bits downwards.
64 * | FIELD | ... | FLAGS |
68 * The fields area is reserved for fields mapping zone, node (for NUMA) and
69 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like
70 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
73 PG_locked
, /* Page is locked. Don't touch. */
81 PG_owner_priv_1
, /* Owner use. If pagecache, fs may use*/
84 PG_private
, /* If pagecache, has fs-private data */
85 PG_private_2
, /* If pagecache, has fs aux data */
86 PG_writeback
, /* Page is under writeback */
87 #ifdef CONFIG_PAGEFLAGS_EXTENDED
88 PG_head
, /* A head page */
89 PG_tail
, /* A tail page */
91 PG_compound
, /* A compound page */
93 PG_swapcache
, /* Swap page: swp_entry_t in private */
94 PG_mappedtodisk
, /* Has blocks allocated on-disk */
95 PG_reclaim
, /* To be reclaimed asap */
96 PG_buddy
, /* Page is free, on buddy lists */
97 PG_swapbacked
, /* Page is backed by RAM/swap */
98 PG_unevictable
, /* Page is "unevictable" */
99 #ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
100 PG_mlocked
, /* Page is vma mlocked */
102 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
103 PG_uncached
, /* Page has been mapped as uncached */
108 PG_checked
= PG_owner_priv_1
,
110 /* Two page bits are conscripted by FS-Cache to maintain local caching
111 * state. These bits are set on pages belonging to the netfs's inodes
112 * when those inodes are being locally cached.
114 PG_fscache
= PG_private_2
, /* page backed by cache */
117 PG_pinned
= PG_owner_priv_1
,
118 PG_savepinned
= PG_dirty
,
121 PG_slob_free
= PG_private
,
124 PG_slub_frozen
= PG_active
,
125 PG_slub_debug
= PG_error
,
128 #ifndef __GENERATING_BOUNDS_H
131 * Macros to create function definitions for page flags
133 #define TESTPAGEFLAG(uname, lname) \
134 static inline int Page##uname(struct page *page) \
135 { return test_bit(PG_##lname, &page->flags); }
137 #define SETPAGEFLAG(uname, lname) \
138 static inline void SetPage##uname(struct page *page) \
139 { set_bit(PG_##lname, &page->flags); }
141 #define CLEARPAGEFLAG(uname, lname) \
142 static inline void ClearPage##uname(struct page *page) \
143 { clear_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 TESTSETFLAG(uname, lname) \
154 static inline int TestSetPage##uname(struct page *page) \
155 { return test_and_set_bit(PG_##lname, &page->flags); }
157 #define TESTCLEARFLAG(uname, lname) \
158 static inline int TestClearPage##uname(struct page *page) \
159 { return test_and_clear_bit(PG_##lname, &page->flags); }
161 #define __TESTCLEARFLAG(uname, lname) \
162 static inline int __TestClearPage##uname(struct page *page) \
163 { return __test_and_clear_bit(PG_##lname, &page->flags); }
165 #define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
166 SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname)
168 #define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
169 __SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname)
171 #define PAGEFLAG_FALSE(uname) \
172 static inline int Page##uname(struct page *page) \
175 #define TESTSCFLAG(uname, lname) \
176 TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)
178 #define SETPAGEFLAG_NOOP(uname) \
179 static inline void SetPage##uname(struct page *page) { }
181 #define CLEARPAGEFLAG_NOOP(uname) \
182 static inline void ClearPage##uname(struct page *page) { }
184 #define __CLEARPAGEFLAG_NOOP(uname) \
185 static inline void __ClearPage##uname(struct page *page) { }
187 #define TESTCLEARFLAG_FALSE(uname) \
188 static inline int TestClearPage##uname(struct page *page) { return 0; }
190 #define __TESTCLEARFLAG_FALSE(uname) \
191 static inline int __TestClearPage##uname(struct page *page) { return 0; }
193 struct page
; /* forward declaration */
195 TESTPAGEFLAG(Locked
, locked
) TESTSETFLAG(Locked
, locked
)
196 PAGEFLAG(Error
, error
)
197 PAGEFLAG(Referenced
, referenced
) TESTCLEARFLAG(Referenced
, referenced
)
198 PAGEFLAG(Dirty
, dirty
) TESTSCFLAG(Dirty
, dirty
) __CLEARPAGEFLAG(Dirty
, dirty
)
199 PAGEFLAG(LRU
, lru
) __CLEARPAGEFLAG(LRU
, lru
)
200 PAGEFLAG(Active
, active
) __CLEARPAGEFLAG(Active
, active
)
201 TESTCLEARFLAG(Active
, active
)
202 __PAGEFLAG(Slab
, slab
)
203 PAGEFLAG(Checked
, checked
) /* Used by some filesystems */
204 PAGEFLAG(Pinned
, pinned
) TESTSCFLAG(Pinned
, pinned
) /* Xen */
205 PAGEFLAG(SavePinned
, savepinned
); /* Xen */
206 PAGEFLAG(Reserved
, reserved
) __CLEARPAGEFLAG(Reserved
, reserved
)
207 PAGEFLAG(SwapBacked
, swapbacked
) __CLEARPAGEFLAG(SwapBacked
, swapbacked
)
209 __PAGEFLAG(SlobFree
, slob_free
)
211 __PAGEFLAG(SlubFrozen
, slub_frozen
)
212 __PAGEFLAG(SlubDebug
, slub_debug
)
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
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
)
225 * Only test-and-set exist for PG_writeback. The unconditional operators are
226 * risky: they bypass page accounting.
228 TESTPAGEFLAG(Writeback
, writeback
) TESTSCFLAG(Writeback
, writeback
)
229 __PAGEFLAG(Buddy
, buddy
)
230 PAGEFLAG(MappedToDisk
, mappedtodisk
)
232 /* PG_readahead is only used for file reads; PG_reclaim is only for writes */
233 PAGEFLAG(Reclaim
, reclaim
) TESTCLEARFLAG(Reclaim
, reclaim
)
234 PAGEFLAG(Readahead
, reclaim
) /* Reminder to do async read-ahead */
236 #ifdef CONFIG_HIGHMEM
238 * Must use a macro here due to header dependency issues. page_zone() is not
239 * available at this point.
241 #define PageHighMem(__p) is_highmem(page_zone(__p))
243 PAGEFLAG_FALSE(HighMem
)
247 PAGEFLAG(SwapCache
, swapcache
)
249 PAGEFLAG_FALSE(SwapCache
)
250 SETPAGEFLAG_NOOP(SwapCache
) CLEARPAGEFLAG_NOOP(SwapCache
)
253 PAGEFLAG(Unevictable
, unevictable
) __CLEARPAGEFLAG(Unevictable
, unevictable
)
254 TESTCLEARFLAG(Unevictable
, unevictable
)
256 #ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
257 #define MLOCK_PAGES 1
258 PAGEFLAG(Mlocked
, mlocked
) __CLEARPAGEFLAG(Mlocked
, mlocked
)
259 TESTSCFLAG(Mlocked
, mlocked
) __TESTCLEARFLAG(Mlocked
, mlocked
)
261 #define MLOCK_PAGES 0
262 PAGEFLAG_FALSE(Mlocked
) SETPAGEFLAG_NOOP(Mlocked
)
263 TESTCLEARFLAG_FALSE(Mlocked
) __TESTCLEARFLAG_FALSE(Mlocked
)
266 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
267 PAGEFLAG(Uncached
, uncached
)
269 PAGEFLAG_FALSE(Uncached
)
272 static inline int PageUptodate(struct page
*page
)
274 int ret
= test_bit(PG_uptodate
, &(page
)->flags
);
277 * Must ensure that the data we read out of the page is loaded
278 * _after_ we've loaded page->flags to check for PageUptodate.
279 * We can skip the barrier if the page is not uptodate, because
280 * we wouldn't be reading anything from it.
282 * See SetPageUptodate() for the other side of the story.
290 static inline void __SetPageUptodate(struct page
*page
)
293 __set_bit(PG_uptodate
, &(page
)->flags
);
296 static inline void SetPageUptodate(struct page
*page
)
299 if (!test_and_set_bit(PG_uptodate
, &page
->flags
))
300 page_clear_dirty(page
);
303 * Memory barrier must be issued before setting the PG_uptodate bit,
304 * so that all previous stores issued in order to bring the page
305 * uptodate are actually visible before PageUptodate becomes true.
307 * s390 doesn't need an explicit smp_wmb here because the test and
308 * set bit already provides full barriers.
311 set_bit(PG_uptodate
, &(page
)->flags
);
315 CLEARPAGEFLAG(Uptodate
, uptodate
)
317 extern void cancel_dirty_page(struct page
*page
, unsigned int account_size
);
319 int test_clear_page_writeback(struct page
*page
);
320 int test_set_page_writeback(struct page
*page
);
322 static inline void set_page_writeback(struct page
*page
)
324 test_set_page_writeback(page
);
327 #ifdef CONFIG_PAGEFLAGS_EXTENDED
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.
334 __PAGEFLAG(Head
, head
)
335 __PAGEFLAG(Tail
, tail
)
337 static inline int PageCompound(struct page
*page
)
339 return page
->flags
& ((1L << PG_head
) | (1L << PG_tail
));
344 * Reduce page flag use as much as possible by overlapping
345 * compound page flags with the flags used for page cache pages. Possible
346 * because PageCompound is always set for compound pages and not for
347 * pages on the LRU and/or pagecache.
349 TESTPAGEFLAG(Compound
, compound
)
350 __PAGEFLAG(Head
, compound
)
353 * PG_reclaim is used in combination with PG_compound to mark the
354 * head and tail of a compound page. This saves one page flag
355 * but makes it impossible to use compound pages for the page cache.
356 * The PG_reclaim bit would have to be used for reclaim or readahead
357 * if compound pages enter the page cache.
359 * PG_compound & PG_reclaim => Tail page
360 * PG_compound & ~PG_reclaim => Head page
362 #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
364 static inline int PageTail(struct page
*page
)
366 return ((page
->flags
& PG_head_tail_mask
) == PG_head_tail_mask
);
369 static inline void __SetPageTail(struct page
*page
)
371 page
->flags
|= PG_head_tail_mask
;
374 static inline void __ClearPageTail(struct page
*page
)
376 page
->flags
&= ~PG_head_tail_mask
;
379 #endif /* !PAGEFLAGS_EXTENDED */
381 #ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
382 #define __PG_MLOCKED (1 << PG_mlocked)
384 #define __PG_MLOCKED 0
388 * Flags checked when a page is freed. Pages being freed should not have
389 * these flags set. It they are, there is a problem.
391 #define PAGE_FLAGS_CHECK_AT_FREE \
392 (1 << PG_lru | 1 << PG_locked | \
393 1 << PG_private | 1 << PG_private_2 | \
394 1 << PG_buddy | 1 << PG_writeback | 1 << PG_reserved | \
395 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
396 1 << PG_unevictable | __PG_MLOCKED)
399 * Flags checked when a page is prepped for return by the page allocator.
400 * Pages being prepped should not have any flags set. It they are set,
401 * there has been a kernel bug or struct page corruption.
403 #define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1)
405 #define PAGE_FLAGS_PRIVATE \
406 (1 << PG_private | 1 << PG_private_2)
408 * page_has_private - Determine if page has private stuff
409 * @page: The page to be checked
411 * Determine if a page has private stuff, indicating that release routines
412 * should be invoked upon it.
414 static inline int page_has_private(struct page
*page
)
416 return !!(page
->flags
& PAGE_FLAGS_PRIVATE
);
419 #endif /* !__GENERATING_BOUNDS_H */
421 #endif /* PAGE_FLAGS_H */
This page took 0.03986 seconds and 6 git commands to generate.