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 TESTSCFLAG(uname, lname) \
175 TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)
177 #define TESTPAGEFLAG_FALSE(uname) \
178 static inline int Page##uname(const struct page *page) { return 0; }
180 #define SETPAGEFLAG_NOOP(uname) \
181 static inline void SetPage##uname(struct page *page) { }
183 #define CLEARPAGEFLAG_NOOP(uname) \
184 static inline void ClearPage##uname(struct page *page) { }
186 #define __CLEARPAGEFLAG_NOOP(uname) \
187 static inline void __ClearPage##uname(struct page *page) { }
189 #define TESTSETFLAG_FALSE(uname) \
190 static inline int TestSetPage##uname(struct page *page) { return 0; }
192 #define TESTCLEARFLAG_FALSE(uname) \
193 static inline int TestClearPage##uname(struct page *page) { return 0; }
195 #define __TESTCLEARFLAG_FALSE(uname) \
196 static inline int __TestClearPage##uname(struct page *page) { return 0; }
198 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \
199 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
201 #define TESTSCFLAG_FALSE(uname) \
202 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
204 struct page
; /* forward declaration */
206 TESTPAGEFLAG(Locked
, locked
)
207 PAGEFLAG(Error
, error
) TESTCLEARFLAG(Error
, error
)
208 PAGEFLAG(Referenced
, referenced
) TESTCLEARFLAG(Referenced
, referenced
)
209 __SETPAGEFLAG(Referenced
, referenced
)
210 PAGEFLAG(Dirty
, dirty
) TESTSCFLAG(Dirty
, dirty
) __CLEARPAGEFLAG(Dirty
, dirty
)
211 PAGEFLAG(LRU
, lru
) __CLEARPAGEFLAG(LRU
, lru
)
212 PAGEFLAG(Active
, active
) __CLEARPAGEFLAG(Active
, active
)
213 TESTCLEARFLAG(Active
, active
)
214 __PAGEFLAG(Slab
, slab
)
215 PAGEFLAG(Checked
, checked
) /* Used by some filesystems */
216 PAGEFLAG(Pinned
, pinned
) TESTSCFLAG(Pinned
, pinned
) /* Xen */
217 PAGEFLAG(SavePinned
, savepinned
); /* Xen */
218 PAGEFLAG(Reserved
, reserved
) __CLEARPAGEFLAG(Reserved
, reserved
)
219 PAGEFLAG(SwapBacked
, swapbacked
) __CLEARPAGEFLAG(SwapBacked
, swapbacked
)
220 __SETPAGEFLAG(SwapBacked
, swapbacked
)
222 __PAGEFLAG(SlobFree
, slob_free
)
225 * Private page markings that may be used by the filesystem that owns the page
226 * for its own purposes.
227 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
229 PAGEFLAG(Private
, private) __SETPAGEFLAG(Private
, private)
230 __CLEARPAGEFLAG(Private
, private)
231 PAGEFLAG(Private2
, private_2
) TESTSCFLAG(Private2
, private_2
)
232 PAGEFLAG(OwnerPriv1
, owner_priv_1
) TESTCLEARFLAG(OwnerPriv1
, owner_priv_1
)
235 * Only test-and-set exist for PG_writeback. The unconditional operators are
236 * risky: they bypass page accounting.
238 TESTPAGEFLAG(Writeback
, writeback
) TESTSCFLAG(Writeback
, writeback
)
239 PAGEFLAG(MappedToDisk
, mappedtodisk
)
241 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
242 PAGEFLAG(Reclaim
, reclaim
) TESTCLEARFLAG(Reclaim
, reclaim
)
243 PAGEFLAG(Readahead
, reclaim
) TESTCLEARFLAG(Readahead
, reclaim
)
245 #ifdef CONFIG_HIGHMEM
247 * Must use a macro here due to header dependency issues. page_zone() is not
248 * available at this point.
250 #define PageHighMem(__p) is_highmem(page_zone(__p))
252 PAGEFLAG_FALSE(HighMem
)
256 PAGEFLAG(SwapCache
, swapcache
)
258 PAGEFLAG_FALSE(SwapCache
)
261 PAGEFLAG(Unevictable
, unevictable
) __CLEARPAGEFLAG(Unevictable
, unevictable
)
262 TESTCLEARFLAG(Unevictable
, unevictable
)
265 PAGEFLAG(Mlocked
, mlocked
) __CLEARPAGEFLAG(Mlocked
, mlocked
)
266 TESTSCFLAG(Mlocked
, mlocked
) __TESTCLEARFLAG(Mlocked
, mlocked
)
268 PAGEFLAG_FALSE(Mlocked
) __CLEARPAGEFLAG_NOOP(Mlocked
)
269 TESTSCFLAG_FALSE(Mlocked
) __TESTCLEARFLAG_FALSE(Mlocked
)
272 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
273 PAGEFLAG(Uncached
, uncached
)
275 PAGEFLAG_FALSE(Uncached
)
278 #ifdef CONFIG_MEMORY_FAILURE
279 PAGEFLAG(HWPoison
, hwpoison
)
280 TESTSCFLAG(HWPoison
, hwpoison
)
281 #define __PG_HWPOISON (1UL << PG_hwpoison)
283 PAGEFLAG_FALSE(HWPoison
)
284 #define __PG_HWPOISON 0
287 u64
stable_page_flags(struct page
*page
);
289 static inline int PageUptodate(struct page
*page
)
291 int ret
= test_bit(PG_uptodate
, &(page
)->flags
);
294 * Must ensure that the data we read out of the page is loaded
295 * _after_ we've loaded page->flags to check for PageUptodate.
296 * We can skip the barrier if the page is not uptodate, because
297 * we wouldn't be reading anything from it.
299 * See SetPageUptodate() for the other side of the story.
307 static inline void __SetPageUptodate(struct page
*page
)
310 __set_bit(PG_uptodate
, &(page
)->flags
);
313 static inline void SetPageUptodate(struct page
*page
)
316 * Memory barrier must be issued before setting the PG_uptodate bit,
317 * so that all previous stores issued in order to bring the page
318 * uptodate are actually visible before PageUptodate becomes true.
321 set_bit(PG_uptodate
, &(page
)->flags
);
324 CLEARPAGEFLAG(Uptodate
, uptodate
)
326 extern void cancel_dirty_page(struct page
*page
, unsigned int account_size
);
328 int test_clear_page_writeback(struct page
*page
);
329 int __test_set_page_writeback(struct page
*page
, bool keep_write
);
331 #define test_set_page_writeback(page) \
332 __test_set_page_writeback(page, false)
333 #define test_set_page_writeback_keepwrite(page) \
334 __test_set_page_writeback(page, true)
336 static inline void set_page_writeback(struct page
*page
)
338 test_set_page_writeback(page
);
341 static inline void set_page_writeback_keepwrite(struct page
*page
)
343 test_set_page_writeback_keepwrite(page
);
346 #ifdef CONFIG_PAGEFLAGS_EXTENDED
348 * System with lots of page flags available. This allows separate
349 * flags for PageHead() and PageTail() checks of compound pages so that bit
350 * tests can be used in performance sensitive paths. PageCompound is
351 * generally not used in hot code paths except arch/powerpc/mm/init_64.c
352 * and arch/powerpc/kvm/book3s_64_vio_hv.c which use it to detect huge pages
353 * and avoid handling those in real mode.
355 __PAGEFLAG(Head
, head
) CLEARPAGEFLAG(Head
, head
)
356 __PAGEFLAG(Tail
, tail
)
358 static inline int PageCompound(struct page
*page
)
360 return page
->flags
& ((1L << PG_head
) | (1L << PG_tail
));
363 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
364 static inline void ClearPageCompound(struct page
*page
)
366 BUG_ON(!PageHead(page
));
371 #define PG_head_mask ((1L << PG_head))
375 * Reduce page flag use as much as possible by overlapping
376 * compound page flags with the flags used for page cache pages. Possible
377 * because PageCompound is always set for compound pages and not for
378 * pages on the LRU and/or pagecache.
380 TESTPAGEFLAG(Compound
, compound
)
381 __SETPAGEFLAG(Head
, compound
) __CLEARPAGEFLAG(Head
, compound
)
384 * PG_reclaim is used in combination with PG_compound to mark the
385 * head and tail of a compound page. This saves one page flag
386 * but makes it impossible to use compound pages for the page cache.
387 * The PG_reclaim bit would have to be used for reclaim or readahead
388 * if compound pages enter the page cache.
390 * PG_compound & PG_reclaim => Tail page
391 * PG_compound & ~PG_reclaim => Head page
393 #define PG_head_mask ((1L << PG_compound))
394 #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
396 static inline int PageHead(struct page
*page
)
398 return ((page
->flags
& PG_head_tail_mask
) == PG_head_mask
);
401 static inline int PageTail(struct page
*page
)
403 return ((page
->flags
& PG_head_tail_mask
) == PG_head_tail_mask
);
406 static inline void __SetPageTail(struct page
*page
)
408 page
->flags
|= PG_head_tail_mask
;
411 static inline void __ClearPageTail(struct page
*page
)
413 page
->flags
&= ~PG_head_tail_mask
;
416 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
417 static inline void ClearPageCompound(struct page
*page
)
419 BUG_ON((page
->flags
& PG_head_tail_mask
) != (1 << PG_compound
));
420 clear_bit(PG_compound
, &page
->flags
);
424 #endif /* !PAGEFLAGS_EXTENDED */
426 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
428 * PageHuge() only returns true for hugetlbfs pages, but not for
429 * normal or transparent huge pages.
431 * PageTransHuge() returns true for both transparent huge and
432 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
433 * called only in the core VM paths where hugetlbfs pages can't exist.
435 static inline int PageTransHuge(struct page
*page
)
437 VM_BUG_ON_PAGE(PageTail(page
), page
);
438 return PageHead(page
);
442 * PageTransCompound returns true for both transparent huge pages
443 * and hugetlbfs pages, so it should only be called when it's known
444 * that hugetlbfs pages aren't involved.
446 static inline int PageTransCompound(struct page
*page
)
448 return PageCompound(page
);
452 * PageTransTail returns true for both transparent huge pages
453 * and hugetlbfs pages, so it should only be called when it's known
454 * that hugetlbfs pages aren't involved.
456 static inline int PageTransTail(struct page
*page
)
458 return PageTail(page
);
463 static inline int PageTransHuge(struct page
*page
)
468 static inline int PageTransCompound(struct page
*page
)
473 static inline int PageTransTail(struct page
*page
)
480 * If network-based swap is enabled, sl*b must keep track of whether pages
481 * were allocated from pfmemalloc reserves.
483 static inline int PageSlabPfmemalloc(struct page
*page
)
485 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
486 return PageActive(page
);
489 static inline void SetPageSlabPfmemalloc(struct page
*page
)
491 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
495 static inline void __ClearPageSlabPfmemalloc(struct page
*page
)
497 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
498 __ClearPageActive(page
);
501 static inline void ClearPageSlabPfmemalloc(struct page
*page
)
503 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
504 ClearPageActive(page
);
508 #define __PG_MLOCKED (1 << PG_mlocked)
510 #define __PG_MLOCKED 0
513 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
514 #define __PG_COMPOUND_LOCK (1 << PG_compound_lock)
516 #define __PG_COMPOUND_LOCK 0
520 * Flags checked when a page is freed. Pages being freed should not have
521 * these flags set. It they are, there is a problem.
523 #define PAGE_FLAGS_CHECK_AT_FREE \
524 (1 << PG_lru | 1 << PG_locked | \
525 1 << PG_private | 1 << PG_private_2 | \
526 1 << PG_writeback | 1 << PG_reserved | \
527 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
528 1 << PG_unevictable | __PG_MLOCKED | __PG_HWPOISON | \
532 * Flags checked when a page is prepped for return by the page allocator.
533 * Pages being prepped should not have any flags set. It they are set,
534 * there has been a kernel bug or struct page corruption.
536 #define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1)
538 #define PAGE_FLAGS_PRIVATE \
539 (1 << PG_private | 1 << PG_private_2)
541 * page_has_private - Determine if page has private stuff
542 * @page: The page to be checked
544 * Determine if a page has private stuff, indicating that release routines
545 * should be invoked upon it.
547 static inline int page_has_private(struct page
*page
)
549 return !!(page
->flags
& PAGE_FLAGS_PRIVATE
);
552 #endif /* !__GENERATING_BOUNDS_H */
554 #endif /* PAGE_FLAGS_H */