2 * Macros for manipulating and testing page->flags
8 #include <linux/types.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 */
17 * Various page->flags bits:
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)...
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.
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.
30 * PG_locked also pins a page in pagecache, and blocks truncation of the file
33 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
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.
39 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
40 * file-backed pagecache (see mm/vmscan.c).
42 * PG_error is set to indicate that an I/O error occurred on this page.
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
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
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!
59 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
60 * locked- and dirty-page accounting.
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.
66 * | FIELD | ... | FLAGS |
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).
75 PG_locked
, /* Page is locked. Don't touch. */
83 PG_owner_priv_1
, /* Owner use. If pagecache, fs may use*/
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 */
93 PG_compound
, /* A compound page */
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" */
101 PG_mlocked
, /* Page is vma mlocked */
103 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
104 PG_uncached
, /* Page has been mapped as uncached */
106 #ifdef CONFIG_MEMORY_FAILURE
107 PG_hwpoison
, /* hardware poisoned page. Don't touch */
109 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
115 PG_checked
= PG_owner_priv_1
,
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.
121 PG_fscache
= PG_private_2
, /* page backed by cache */
124 PG_pinned
= PG_owner_priv_1
,
125 PG_savepinned
= PG_dirty
,
128 PG_slob_free
= PG_private
,
131 #ifndef __GENERATING_BOUNDS_H
134 * Macros to create function definitions for page flags
136 #define TESTPAGEFLAG(uname, lname) \
137 static inline int Page##uname(const struct page *page) \
138 { return test_bit(PG_##lname, &page->flags); }
140 #define SETPAGEFLAG(uname, lname) \
141 static inline void SetPage##uname(struct page *page) \
142 { set_bit(PG_##lname, &page->flags); }
144 #define CLEARPAGEFLAG(uname, lname) \
145 static inline void ClearPage##uname(struct page *page) \
146 { clear_bit(PG_##lname, &page->flags); }
148 #define __SETPAGEFLAG(uname, lname) \
149 static inline void __SetPage##uname(struct page *page) \
150 { __set_bit(PG_##lname, &page->flags); }
152 #define __CLEARPAGEFLAG(uname, lname) \
153 static inline void __ClearPage##uname(struct page *page) \
154 { __clear_bit(PG_##lname, &page->flags); }
156 #define TESTSETFLAG(uname, lname) \
157 static inline int TestSetPage##uname(struct page *page) \
158 { return test_and_set_bit(PG_##lname, &page->flags); }
160 #define TESTCLEARFLAG(uname, lname) \
161 static inline int TestClearPage##uname(struct page *page) \
162 { return test_and_clear_bit(PG_##lname, &page->flags); }
164 #define __TESTCLEARFLAG(uname, lname) \
165 static inline int __TestClearPage##uname(struct page *page) \
166 { return __test_and_clear_bit(PG_##lname, &page->flags); }
168 #define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
169 SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname)
171 #define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
172 __SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname)
174 #define PAGEFLAG_FALSE(uname) \
175 static inline int Page##uname(const struct page *page) \
178 #define TESTSCFLAG(uname, lname) \
179 TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)
181 #define SETPAGEFLAG_NOOP(uname) \
182 static inline void SetPage##uname(struct page *page) { }
184 #define CLEARPAGEFLAG_NOOP(uname) \
185 static inline void ClearPage##uname(struct page *page) { }
187 #define __CLEARPAGEFLAG_NOOP(uname) \
188 static inline void __ClearPage##uname(struct page *page) { }
190 #define TESTCLEARFLAG_FALSE(uname) \
191 static inline int TestClearPage##uname(struct page *page) { return 0; }
193 #define __TESTCLEARFLAG_FALSE(uname) \
194 static inline int __TestClearPage##uname(struct page *page) { return 0; }
196 struct page
; /* forward declaration */
198 TESTPAGEFLAG(Locked
, locked
)
199 PAGEFLAG(Error
, error
) TESTCLEARFLAG(Error
, error
)
200 PAGEFLAG(Referenced
, referenced
) TESTCLEARFLAG(Referenced
, referenced
)
201 __SETPAGEFLAG(Referenced
, referenced
)
202 PAGEFLAG(Dirty
, dirty
) TESTSCFLAG(Dirty
, dirty
) __CLEARPAGEFLAG(Dirty
, dirty
)
203 PAGEFLAG(LRU
, lru
) __CLEARPAGEFLAG(LRU
, lru
)
204 PAGEFLAG(Active
, active
) __CLEARPAGEFLAG(Active
, active
)
205 TESTCLEARFLAG(Active
, active
)
206 __PAGEFLAG(Slab
, slab
)
207 PAGEFLAG(Checked
, checked
) /* Used by some filesystems */
208 PAGEFLAG(Pinned
, pinned
) TESTSCFLAG(Pinned
, pinned
) /* Xen */
209 PAGEFLAG(SavePinned
, savepinned
); /* Xen */
210 PAGEFLAG(Reserved
, reserved
) __CLEARPAGEFLAG(Reserved
, reserved
)
211 PAGEFLAG(SwapBacked
, swapbacked
) __CLEARPAGEFLAG(SwapBacked
, swapbacked
)
212 __SETPAGEFLAG(SwapBacked
, swapbacked
)
214 __PAGEFLAG(SlobFree
, slob_free
)
217 * Private page markings that may be used by the filesystem that owns the page
218 * for its own purposes.
219 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
221 PAGEFLAG(Private
, private) __SETPAGEFLAG(Private
, private)
222 __CLEARPAGEFLAG(Private
, private)
223 PAGEFLAG(Private2
, private_2
) TESTSCFLAG(Private2
, private_2
)
224 PAGEFLAG(OwnerPriv1
, owner_priv_1
) TESTCLEARFLAG(OwnerPriv1
, owner_priv_1
)
227 * Only test-and-set exist for PG_writeback. The unconditional operators are
228 * risky: they bypass page accounting.
230 TESTPAGEFLAG(Writeback
, writeback
) TESTSCFLAG(Writeback
, writeback
)
231 PAGEFLAG(MappedToDisk
, mappedtodisk
)
233 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
234 PAGEFLAG(Reclaim
, reclaim
) TESTCLEARFLAG(Reclaim
, reclaim
)
235 PAGEFLAG(Readahead
, reclaim
) TESTCLEARFLAG(Readahead
, reclaim
)
237 #ifdef CONFIG_HIGHMEM
239 * Must use a macro here due to header dependency issues. page_zone() is not
240 * available at this point.
242 #define PageHighMem(__p) is_highmem(page_zone(__p))
244 PAGEFLAG_FALSE(HighMem
)
248 PAGEFLAG(SwapCache
, swapcache
)
250 PAGEFLAG_FALSE(SwapCache
)
251 SETPAGEFLAG_NOOP(SwapCache
) CLEARPAGEFLAG_NOOP(SwapCache
)
254 PAGEFLAG(Unevictable
, unevictable
) __CLEARPAGEFLAG(Unevictable
, unevictable
)
255 TESTCLEARFLAG(Unevictable
, unevictable
)
258 PAGEFLAG(Mlocked
, mlocked
) __CLEARPAGEFLAG(Mlocked
, mlocked
)
259 TESTSCFLAG(Mlocked
, mlocked
) __TESTCLEARFLAG(Mlocked
, mlocked
)
261 PAGEFLAG_FALSE(Mlocked
) SETPAGEFLAG_NOOP(Mlocked
)
262 TESTCLEARFLAG_FALSE(Mlocked
) __TESTCLEARFLAG_FALSE(Mlocked
)
265 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
266 PAGEFLAG(Uncached
, uncached
)
268 PAGEFLAG_FALSE(Uncached
)
271 #ifdef CONFIG_MEMORY_FAILURE
272 PAGEFLAG(HWPoison
, hwpoison
)
273 TESTSCFLAG(HWPoison
, hwpoison
)
274 #define __PG_HWPOISON (1UL << PG_hwpoison)
276 PAGEFLAG_FALSE(HWPoison
)
277 #define __PG_HWPOISON 0
280 u64
stable_page_flags(struct page
*page
);
282 static inline int PageUptodate(struct page
*page
)
284 int ret
= test_bit(PG_uptodate
, &(page
)->flags
);
287 * Must ensure that the data we read out of the page is loaded
288 * _after_ we've loaded page->flags to check for PageUptodate.
289 * We can skip the barrier if the page is not uptodate, because
290 * we wouldn't be reading anything from it.
292 * See SetPageUptodate() for the other side of the story.
300 static inline void __SetPageUptodate(struct page
*page
)
303 __set_bit(PG_uptodate
, &(page
)->flags
);
306 static inline void SetPageUptodate(struct page
*page
)
309 * Memory barrier must be issued before setting the PG_uptodate bit,
310 * so that all previous stores issued in order to bring the page
311 * uptodate are actually visible before PageUptodate becomes true.
314 set_bit(PG_uptodate
, &(page
)->flags
);
317 CLEARPAGEFLAG(Uptodate
, uptodate
)
319 extern void cancel_dirty_page(struct page
*page
, unsigned int account_size
);
321 int test_clear_page_writeback(struct page
*page
);
322 int test_set_page_writeback(struct page
*page
);
324 static inline void set_page_writeback(struct page
*page
)
326 test_set_page_writeback(page
);
329 #ifdef CONFIG_PAGEFLAGS_EXTENDED
331 * System with lots of page flags available. This allows separate
332 * flags for PageHead() and PageTail() checks of compound pages so that bit
333 * tests can be used in performance sensitive paths. PageCompound is
334 * generally not used in hot code paths except arch/powerpc/mm/init_64.c
335 * and arch/powerpc/kvm/book3s_64_vio_hv.c which use it to detect huge pages
336 * and avoid handling those in real mode.
338 __PAGEFLAG(Head
, head
) CLEARPAGEFLAG(Head
, head
)
339 __PAGEFLAG(Tail
, tail
)
341 static inline int PageCompound(struct page
*page
)
343 return page
->flags
& ((1L << PG_head
) | (1L << PG_tail
));
346 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
347 static inline void ClearPageCompound(struct page
*page
)
349 BUG_ON(!PageHead(page
));
355 * Reduce page flag use as much as possible by overlapping
356 * compound page flags with the flags used for page cache pages. Possible
357 * because PageCompound is always set for compound pages and not for
358 * pages on the LRU and/or pagecache.
360 TESTPAGEFLAG(Compound
, compound
)
361 __SETPAGEFLAG(Head
, compound
) __CLEARPAGEFLAG(Head
, compound
)
364 * PG_reclaim is used in combination with PG_compound to mark the
365 * head and tail of a compound page. This saves one page flag
366 * but makes it impossible to use compound pages for the page cache.
367 * The PG_reclaim bit would have to be used for reclaim or readahead
368 * if compound pages enter the page cache.
370 * PG_compound & PG_reclaim => Tail page
371 * PG_compound & ~PG_reclaim => Head page
373 #define PG_head_mask ((1L << PG_compound))
374 #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
376 static inline int PageHead(struct page
*page
)
378 return ((page
->flags
& PG_head_tail_mask
) == PG_head_mask
);
381 static inline int PageTail(struct page
*page
)
383 return ((page
->flags
& PG_head_tail_mask
) == PG_head_tail_mask
);
386 static inline void __SetPageTail(struct page
*page
)
388 page
->flags
|= PG_head_tail_mask
;
391 static inline void __ClearPageTail(struct page
*page
)
393 page
->flags
&= ~PG_head_tail_mask
;
396 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
397 static inline void ClearPageCompound(struct page
*page
)
399 BUG_ON((page
->flags
& PG_head_tail_mask
) != (1 << PG_compound
));
400 clear_bit(PG_compound
, &page
->flags
);
404 #endif /* !PAGEFLAGS_EXTENDED */
406 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
408 * PageHuge() only returns true for hugetlbfs pages, but not for
409 * normal or transparent huge pages.
411 * PageTransHuge() returns true for both transparent huge and
412 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
413 * called only in the core VM paths where hugetlbfs pages can't exist.
415 static inline int PageTransHuge(struct page
*page
)
417 VM_BUG_ON_PAGE(PageTail(page
), page
);
418 return PageHead(page
);
422 * PageTransCompound returns true for both transparent huge pages
423 * and hugetlbfs pages, so it should only be called when it's known
424 * that hugetlbfs pages aren't involved.
426 static inline int PageTransCompound(struct page
*page
)
428 return PageCompound(page
);
432 * PageTransTail returns true for both transparent huge pages
433 * and hugetlbfs pages, so it should only be called when it's known
434 * that hugetlbfs pages aren't involved.
436 static inline int PageTransTail(struct page
*page
)
438 return PageTail(page
);
443 static inline int PageTransHuge(struct page
*page
)
448 static inline int PageTransCompound(struct page
*page
)
453 static inline int PageTransTail(struct page
*page
)
460 * If network-based swap is enabled, sl*b must keep track of whether pages
461 * were allocated from pfmemalloc reserves.
463 static inline int PageSlabPfmemalloc(struct page
*page
)
465 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
466 return PageActive(page
);
469 static inline void SetPageSlabPfmemalloc(struct page
*page
)
471 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
475 static inline void __ClearPageSlabPfmemalloc(struct page
*page
)
477 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
478 __ClearPageActive(page
);
481 static inline void ClearPageSlabPfmemalloc(struct page
*page
)
483 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
484 ClearPageActive(page
);
488 #define __PG_MLOCKED (1 << PG_mlocked)
490 #define __PG_MLOCKED 0
493 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
494 #define __PG_COMPOUND_LOCK (1 << PG_compound_lock)
496 #define __PG_COMPOUND_LOCK 0
500 * Flags checked when a page is freed. Pages being freed should not have
501 * these flags set. It they are, there is a problem.
503 #define PAGE_FLAGS_CHECK_AT_FREE \
504 (1 << PG_lru | 1 << PG_locked | \
505 1 << PG_private | 1 << PG_private_2 | \
506 1 << PG_writeback | 1 << PG_reserved | \
507 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
508 1 << PG_unevictable | __PG_MLOCKED | __PG_HWPOISON | \
512 * Flags checked when a page is prepped for return by the page allocator.
513 * Pages being prepped should not have any flags set. It they are set,
514 * there has been a kernel bug or struct page corruption.
516 #define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1)
518 #define PAGE_FLAGS_PRIVATE \
519 (1 << PG_private | 1 << PG_private_2)
521 * page_has_private - Determine if page has private stuff
522 * @page: The page to be checked
524 * Determine if a page has private stuff, indicating that release routines
525 * should be invoked upon it.
527 static inline int page_has_private(struct page
*page
)
529 return !!(page
->flags
& PAGE_FLAGS_PRIVATE
);
532 #endif /* !__GENERATING_BOUNDS_H */
534 #endif /* PAGE_FLAGS_H */
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