]>
git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - include/linux/page-flags.h
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. */
82 PG_waiters
, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
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 PG_head
, /* A head page */
91 PG_mappedtodisk
, /* Has blocks allocated on-disk */
92 PG_reclaim
, /* To be reclaimed asap */
93 PG_swapbacked
, /* Page is backed by RAM/swap */
94 PG_unevictable
, /* Page is "unevictable" */
96 PG_mlocked
, /* Page is vma mlocked */
98 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
99 PG_uncached
, /* Page has been mapped as uncached */
101 #ifdef CONFIG_MEMORY_FAILURE
102 PG_hwpoison
, /* hardware poisoned page. Don't touch */
104 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
111 PG_checked
= PG_owner_priv_1
,
114 PG_swapcache
= PG_owner_priv_1
, /* Swap page: swp_entry_t in private */
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.
120 PG_fscache
= PG_private_2
, /* page backed by cache */
123 /* Pinned in Xen as a read-only pagetable page. */
124 PG_pinned
= PG_owner_priv_1
,
125 /* Pinned as part of domain save (see xen_mm_pin_all()). */
126 PG_savepinned
= PG_dirty
,
127 /* Has a grant mapping of another (foreign) domain's page. */
128 PG_foreign
= PG_owner_priv_1
,
131 PG_slob_free
= PG_private
,
133 /* Compound pages. Stored in first tail page's flags */
134 PG_double_map
= PG_private_2
,
136 /* non-lru isolated movable page */
137 PG_isolated
= PG_reclaim
,
140 #ifndef __GENERATING_BOUNDS_H
142 struct page
; /* forward declaration */
144 static inline struct page
*compound_head(struct page
*page
)
146 unsigned long head
= READ_ONCE(page
->compound_head
);
148 if (unlikely(head
& 1))
149 return (struct page
*) (head
- 1);
153 static __always_inline
int PageTail(struct page
*page
)
155 return READ_ONCE(page
->compound_head
) & 1;
158 static __always_inline
int PageCompound(struct page
*page
)
160 return test_bit(PG_head
, &page
->flags
) || PageTail(page
);
164 * Page flags policies wrt compound pages
167 * the page flag is relevant for small, head and tail pages.
170 * for compound page all operations related to the page flag applied to
174 * for compound page, callers only ever operate on the head page.
177 * modifications of the page flag must be done on small or head pages,
178 * checks can be done on tail pages too.
181 * the page flag is not relevant for compound pages.
183 #define PF_ANY(page, enforce) page
184 #define PF_HEAD(page, enforce) compound_head(page)
185 #define PF_ONLY_HEAD(page, enforce) ({ \
186 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
188 #define PF_NO_TAIL(page, enforce) ({ \
189 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
190 compound_head(page);})
191 #define PF_NO_COMPOUND(page, enforce) ({ \
192 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
196 * Macros to create function definitions for page flags
198 #define TESTPAGEFLAG(uname, lname, policy) \
199 static __always_inline int Page##uname(struct page *page) \
200 { return test_bit(PG_##lname, &policy(page, 0)->flags); }
202 #define SETPAGEFLAG(uname, lname, policy) \
203 static __always_inline void SetPage##uname(struct page *page) \
204 { set_bit(PG_##lname, &policy(page, 1)->flags); }
206 #define CLEARPAGEFLAG(uname, lname, policy) \
207 static __always_inline void ClearPage##uname(struct page *page) \
208 { clear_bit(PG_##lname, &policy(page, 1)->flags); }
210 #define __SETPAGEFLAG(uname, lname, policy) \
211 static __always_inline void __SetPage##uname(struct page *page) \
212 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
214 #define __CLEARPAGEFLAG(uname, lname, policy) \
215 static __always_inline void __ClearPage##uname(struct page *page) \
216 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
218 #define TESTSETFLAG(uname, lname, policy) \
219 static __always_inline int TestSetPage##uname(struct page *page) \
220 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
222 #define TESTCLEARFLAG(uname, lname, policy) \
223 static __always_inline int TestClearPage##uname(struct page *page) \
224 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
226 #define PAGEFLAG(uname, lname, policy) \
227 TESTPAGEFLAG(uname, lname, policy) \
228 SETPAGEFLAG(uname, lname, policy) \
229 CLEARPAGEFLAG(uname, lname, policy)
231 #define __PAGEFLAG(uname, lname, policy) \
232 TESTPAGEFLAG(uname, lname, policy) \
233 __SETPAGEFLAG(uname, lname, policy) \
234 __CLEARPAGEFLAG(uname, lname, policy)
236 #define TESTSCFLAG(uname, lname, policy) \
237 TESTSETFLAG(uname, lname, policy) \
238 TESTCLEARFLAG(uname, lname, policy)
240 #define TESTPAGEFLAG_FALSE(uname) \
241 static inline int Page##uname(const struct page *page) { return 0; }
243 #define SETPAGEFLAG_NOOP(uname) \
244 static inline void SetPage##uname(struct page *page) { }
246 #define CLEARPAGEFLAG_NOOP(uname) \
247 static inline void ClearPage##uname(struct page *page) { }
249 #define __CLEARPAGEFLAG_NOOP(uname) \
250 static inline void __ClearPage##uname(struct page *page) { }
252 #define TESTSETFLAG_FALSE(uname) \
253 static inline int TestSetPage##uname(struct page *page) { return 0; }
255 #define TESTCLEARFLAG_FALSE(uname) \
256 static inline int TestClearPage##uname(struct page *page) { return 0; }
258 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \
259 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
261 #define TESTSCFLAG_FALSE(uname) \
262 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
264 __PAGEFLAG(Locked
, locked
, PF_NO_TAIL
)
265 PAGEFLAG(Waiters
, waiters
, PF_ONLY_HEAD
) __CLEARPAGEFLAG(Waiters
, waiters
, PF_ONLY_HEAD
)
266 PAGEFLAG(Error
, error
, PF_NO_COMPOUND
) TESTCLEARFLAG(Error
, error
, PF_NO_COMPOUND
)
267 PAGEFLAG(Referenced
, referenced
, PF_HEAD
)
268 TESTCLEARFLAG(Referenced
, referenced
, PF_HEAD
)
269 __SETPAGEFLAG(Referenced
, referenced
, PF_HEAD
)
270 PAGEFLAG(Dirty
, dirty
, PF_HEAD
) TESTSCFLAG(Dirty
, dirty
, PF_HEAD
)
271 __CLEARPAGEFLAG(Dirty
, dirty
, PF_HEAD
)
272 PAGEFLAG(LRU
, lru
, PF_HEAD
) __CLEARPAGEFLAG(LRU
, lru
, PF_HEAD
)
273 PAGEFLAG(Active
, active
, PF_HEAD
) __CLEARPAGEFLAG(Active
, active
, PF_HEAD
)
274 TESTCLEARFLAG(Active
, active
, PF_HEAD
)
275 __PAGEFLAG(Slab
, slab
, PF_NO_TAIL
)
276 __PAGEFLAG(SlobFree
, slob_free
, PF_NO_TAIL
)
277 PAGEFLAG(Checked
, checked
, PF_NO_COMPOUND
) /* Used by some filesystems */
280 PAGEFLAG(Pinned
, pinned
, PF_NO_COMPOUND
)
281 TESTSCFLAG(Pinned
, pinned
, PF_NO_COMPOUND
)
282 PAGEFLAG(SavePinned
, savepinned
, PF_NO_COMPOUND
);
283 PAGEFLAG(Foreign
, foreign
, PF_NO_COMPOUND
);
285 PAGEFLAG(Reserved
, reserved
, PF_NO_COMPOUND
)
286 __CLEARPAGEFLAG(Reserved
, reserved
, PF_NO_COMPOUND
)
287 PAGEFLAG(SwapBacked
, swapbacked
, PF_NO_TAIL
)
288 __CLEARPAGEFLAG(SwapBacked
, swapbacked
, PF_NO_TAIL
)
289 __SETPAGEFLAG(SwapBacked
, swapbacked
, PF_NO_TAIL
)
292 * Private page markings that may be used by the filesystem that owns the page
293 * for its own purposes.
294 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
296 PAGEFLAG(Private
, private, PF_ANY
) __SETPAGEFLAG(Private
, private, PF_ANY
)
297 __CLEARPAGEFLAG(Private
, private, PF_ANY
)
298 PAGEFLAG(Private2
, private_2
, PF_ANY
) TESTSCFLAG(Private2
, private_2
, PF_ANY
)
299 PAGEFLAG(OwnerPriv1
, owner_priv_1
, PF_ANY
)
300 TESTCLEARFLAG(OwnerPriv1
, owner_priv_1
, PF_ANY
)
303 * Only test-and-set exist for PG_writeback. The unconditional operators are
304 * risky: they bypass page accounting.
306 TESTPAGEFLAG(Writeback
, writeback
, PF_NO_COMPOUND
)
307 TESTSCFLAG(Writeback
, writeback
, PF_NO_COMPOUND
)
308 PAGEFLAG(MappedToDisk
, mappedtodisk
, PF_NO_TAIL
)
310 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
311 PAGEFLAG(Reclaim
, reclaim
, PF_NO_TAIL
)
312 TESTCLEARFLAG(Reclaim
, reclaim
, PF_NO_TAIL
)
313 PAGEFLAG(Readahead
, reclaim
, PF_NO_COMPOUND
)
314 TESTCLEARFLAG(Readahead
, reclaim
, PF_NO_COMPOUND
)
316 #ifdef CONFIG_HIGHMEM
318 * Must use a macro here due to header dependency issues. page_zone() is not
319 * available at this point.
321 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
323 PAGEFLAG_FALSE(HighMem
)
327 static __always_inline
int PageSwapCache(struct page
*page
)
329 #ifdef CONFIG_THP_SWAP
330 page
= compound_head(page
);
332 return PageSwapBacked(page
) && test_bit(PG_swapcache
, &page
->flags
);
335 SETPAGEFLAG(SwapCache
, swapcache
, PF_NO_TAIL
)
336 CLEARPAGEFLAG(SwapCache
, swapcache
, PF_NO_TAIL
)
338 PAGEFLAG_FALSE(SwapCache
)
341 PAGEFLAG(Unevictable
, unevictable
, PF_HEAD
)
342 __CLEARPAGEFLAG(Unevictable
, unevictable
, PF_HEAD
)
343 TESTCLEARFLAG(Unevictable
, unevictable
, PF_HEAD
)
346 PAGEFLAG(Mlocked
, mlocked
, PF_NO_TAIL
)
347 __CLEARPAGEFLAG(Mlocked
, mlocked
, PF_NO_TAIL
)
348 TESTSCFLAG(Mlocked
, mlocked
, PF_NO_TAIL
)
350 PAGEFLAG_FALSE(Mlocked
) __CLEARPAGEFLAG_NOOP(Mlocked
)
351 TESTSCFLAG_FALSE(Mlocked
)
354 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
355 PAGEFLAG(Uncached
, uncached
, PF_NO_COMPOUND
)
357 PAGEFLAG_FALSE(Uncached
)
360 #ifdef CONFIG_MEMORY_FAILURE
361 PAGEFLAG(HWPoison
, hwpoison
, PF_ANY
)
362 TESTSCFLAG(HWPoison
, hwpoison
, PF_ANY
)
363 #define __PG_HWPOISON (1UL << PG_hwpoison)
365 PAGEFLAG_FALSE(HWPoison
)
366 #define __PG_HWPOISON 0
369 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
370 TESTPAGEFLAG(Young
, young
, PF_ANY
)
371 SETPAGEFLAG(Young
, young
, PF_ANY
)
372 TESTCLEARFLAG(Young
, young
, PF_ANY
)
373 PAGEFLAG(Idle
, idle
, PF_ANY
)
377 * On an anonymous page mapped into a user virtual memory area,
378 * page->mapping points to its anon_vma, not to a struct address_space;
379 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
381 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
382 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
383 * bit; and then page->mapping points, not to an anon_vma, but to a private
384 * structure which KSM associates with that merged page. See ksm.h.
386 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
387 * page and then page->mapping points a struct address_space.
389 * Please note that, confusingly, "page_mapping" refers to the inode
390 * address_space which maps the page from disk; whereas "page_mapped"
391 * refers to user virtual address space into which the page is mapped.
393 #define PAGE_MAPPING_ANON 0x1
394 #define PAGE_MAPPING_MOVABLE 0x2
395 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
396 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
398 static __always_inline
int PageMappingFlags(struct page
*page
)
400 return ((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) != 0;
403 static __always_inline
int PageAnon(struct page
*page
)
405 page
= compound_head(page
);
406 return ((unsigned long)page
->mapping
& PAGE_MAPPING_ANON
) != 0;
409 static __always_inline
int __PageMovable(struct page
*page
)
411 return ((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) ==
412 PAGE_MAPPING_MOVABLE
;
417 * A KSM page is one of those write-protected "shared pages" or "merged pages"
418 * which KSM maps into multiple mms, wherever identical anonymous page content
419 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
420 * anon_vma, but to that page's node of the stable tree.
422 static __always_inline
int PageKsm(struct page
*page
)
424 page
= compound_head(page
);
425 return ((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) ==
429 TESTPAGEFLAG_FALSE(Ksm
)
432 u64
stable_page_flags(struct page
*page
);
434 static inline int PageUptodate(struct page
*page
)
437 page
= compound_head(page
);
438 ret
= test_bit(PG_uptodate
, &(page
)->flags
);
440 * Must ensure that the data we read out of the page is loaded
441 * _after_ we've loaded page->flags to check for PageUptodate.
442 * We can skip the barrier if the page is not uptodate, because
443 * we wouldn't be reading anything from it.
445 * See SetPageUptodate() for the other side of the story.
453 static __always_inline
void __SetPageUptodate(struct page
*page
)
455 VM_BUG_ON_PAGE(PageTail(page
), page
);
457 __set_bit(PG_uptodate
, &page
->flags
);
460 static __always_inline
void SetPageUptodate(struct page
*page
)
462 VM_BUG_ON_PAGE(PageTail(page
), page
);
464 * Memory barrier must be issued before setting the PG_uptodate bit,
465 * so that all previous stores issued in order to bring the page
466 * uptodate are actually visible before PageUptodate becomes true.
469 set_bit(PG_uptodate
, &page
->flags
);
472 CLEARPAGEFLAG(Uptodate
, uptodate
, PF_NO_TAIL
)
474 int test_clear_page_writeback(struct page
*page
);
475 int __test_set_page_writeback(struct page
*page
, bool keep_write
);
477 #define test_set_page_writeback(page) \
478 __test_set_page_writeback(page, false)
479 #define test_set_page_writeback_keepwrite(page) \
480 __test_set_page_writeback(page, true)
482 static inline void set_page_writeback(struct page
*page
)
484 test_set_page_writeback(page
);
487 static inline void set_page_writeback_keepwrite(struct page
*page
)
489 test_set_page_writeback_keepwrite(page
);
492 __PAGEFLAG(Head
, head
, PF_ANY
) CLEARPAGEFLAG(Head
, head
, PF_ANY
)
494 static __always_inline
void set_compound_head(struct page
*page
, struct page
*head
)
496 WRITE_ONCE(page
->compound_head
, (unsigned long)head
+ 1);
499 static __always_inline
void clear_compound_head(struct page
*page
)
501 WRITE_ONCE(page
->compound_head
, 0);
504 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
505 static inline void ClearPageCompound(struct page
*page
)
507 BUG_ON(!PageHead(page
));
512 #define PG_head_mask ((1UL << PG_head))
514 #ifdef CONFIG_HUGETLB_PAGE
515 int PageHuge(struct page
*page
);
516 int PageHeadHuge(struct page
*page
);
517 bool page_huge_active(struct page
*page
);
519 TESTPAGEFLAG_FALSE(Huge
)
520 TESTPAGEFLAG_FALSE(HeadHuge
)
522 static inline bool page_huge_active(struct page
*page
)
529 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
531 * PageHuge() only returns true for hugetlbfs pages, but not for
532 * normal or transparent huge pages.
534 * PageTransHuge() returns true for both transparent huge and
535 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
536 * called only in the core VM paths where hugetlbfs pages can't exist.
538 static inline int PageTransHuge(struct page
*page
)
540 VM_BUG_ON_PAGE(PageTail(page
), page
);
541 return PageHead(page
);
545 * PageTransCompound returns true for both transparent huge pages
546 * and hugetlbfs pages, so it should only be called when it's known
547 * that hugetlbfs pages aren't involved.
549 static inline int PageTransCompound(struct page
*page
)
551 return PageCompound(page
);
555 * PageTransCompoundMap is the same as PageTransCompound, but it also
556 * guarantees the primary MMU has the entire compound page mapped
557 * through pmd_trans_huge, which in turn guarantees the secondary MMUs
558 * can also map the entire compound page. This allows the secondary
559 * MMUs to call get_user_pages() only once for each compound page and
560 * to immediately map the entire compound page with a single secondary
561 * MMU fault. If there will be a pmd split later, the secondary MMUs
562 * will get an update through the MMU notifier invalidation through
565 * Unlike PageTransCompound, this is safe to be called only while
566 * split_huge_pmd() cannot run from under us, like if protected by the
567 * MMU notifier, otherwise it may result in page->_mapcount < 0 false
570 static inline int PageTransCompoundMap(struct page
*page
)
572 return PageTransCompound(page
) && atomic_read(&page
->_mapcount
) < 0;
576 * PageTransTail returns true for both transparent huge pages
577 * and hugetlbfs pages, so it should only be called when it's known
578 * that hugetlbfs pages aren't involved.
580 static inline int PageTransTail(struct page
*page
)
582 return PageTail(page
);
586 * PageDoubleMap indicates that the compound page is mapped with PTEs as well
589 * This is required for optimization of rmap operations for THP: we can postpone
590 * per small page mapcount accounting (and its overhead from atomic operations)
591 * until the first PMD split.
593 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
594 * by one. This reference will go away with last compound_mapcount.
596 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
598 static inline int PageDoubleMap(struct page
*page
)
600 return PageHead(page
) && test_bit(PG_double_map
, &page
[1].flags
);
603 static inline void SetPageDoubleMap(struct page
*page
)
605 VM_BUG_ON_PAGE(!PageHead(page
), page
);
606 set_bit(PG_double_map
, &page
[1].flags
);
609 static inline void ClearPageDoubleMap(struct page
*page
)
611 VM_BUG_ON_PAGE(!PageHead(page
), page
);
612 clear_bit(PG_double_map
, &page
[1].flags
);
614 static inline int TestSetPageDoubleMap(struct page
*page
)
616 VM_BUG_ON_PAGE(!PageHead(page
), page
);
617 return test_and_set_bit(PG_double_map
, &page
[1].flags
);
620 static inline int TestClearPageDoubleMap(struct page
*page
)
622 VM_BUG_ON_PAGE(!PageHead(page
), page
);
623 return test_and_clear_bit(PG_double_map
, &page
[1].flags
);
627 TESTPAGEFLAG_FALSE(TransHuge
)
628 TESTPAGEFLAG_FALSE(TransCompound
)
629 TESTPAGEFLAG_FALSE(TransCompoundMap
)
630 TESTPAGEFLAG_FALSE(TransTail
)
631 PAGEFLAG_FALSE(DoubleMap
)
632 TESTSETFLAG_FALSE(DoubleMap
)
633 TESTCLEARFLAG_FALSE(DoubleMap
)
637 * For pages that are never mapped to userspace, page->mapcount may be
638 * used for storing extra information about page type. Any value used
639 * for this purpose must be <= -2, but it's better start not too close
640 * to -2 so that an underflow of the page_mapcount() won't be mistaken
641 * for a special page.
643 #define PAGE_MAPCOUNT_OPS(uname, lname) \
644 static __always_inline int Page##uname(struct page *page) \
646 return atomic_read(&page->_mapcount) == \
647 PAGE_##lname##_MAPCOUNT_VALUE; \
649 static __always_inline void __SetPage##uname(struct page *page) \
651 VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page); \
652 atomic_set(&page->_mapcount, PAGE_##lname##_MAPCOUNT_VALUE); \
654 static __always_inline void __ClearPage##uname(struct page *page) \
656 VM_BUG_ON_PAGE(!Page##uname(page), page); \
657 atomic_set(&page->_mapcount, -1); \
661 * PageBuddy() indicate that the page is free and in the buddy system
662 * (see mm/page_alloc.c).
664 #define PAGE_BUDDY_MAPCOUNT_VALUE (-128)
665 PAGE_MAPCOUNT_OPS(Buddy
, BUDDY
)
668 * PageBalloon() is set on pages that are on the balloon page list
669 * (see mm/balloon_compaction.c).
671 #define PAGE_BALLOON_MAPCOUNT_VALUE (-256)
672 PAGE_MAPCOUNT_OPS(Balloon
, BALLOON
)
675 * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on
676 * pages allocated with __GFP_ACCOUNT. It gets cleared on page free.
678 #define PAGE_KMEMCG_MAPCOUNT_VALUE (-512)
679 PAGE_MAPCOUNT_OPS(Kmemcg
, KMEMCG
)
681 extern bool is_free_buddy_page(struct page
*page
);
683 __PAGEFLAG(Isolated
, isolated
, PF_ANY
);
686 * If network-based swap is enabled, sl*b must keep track of whether pages
687 * were allocated from pfmemalloc reserves.
689 static inline int PageSlabPfmemalloc(struct page
*page
)
691 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
692 return PageActive(page
);
695 static inline void SetPageSlabPfmemalloc(struct page
*page
)
697 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
701 static inline void __ClearPageSlabPfmemalloc(struct page
*page
)
703 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
704 __ClearPageActive(page
);
707 static inline void ClearPageSlabPfmemalloc(struct page
*page
)
709 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
710 ClearPageActive(page
);
714 #define __PG_MLOCKED (1UL << PG_mlocked)
716 #define __PG_MLOCKED 0
720 * Flags checked when a page is freed. Pages being freed should not have
721 * these flags set. It they are, there is a problem.
723 #define PAGE_FLAGS_CHECK_AT_FREE \
724 (1UL << PG_lru | 1UL << PG_locked | \
725 1UL << PG_private | 1UL << PG_private_2 | \
726 1UL << PG_writeback | 1UL << PG_reserved | \
727 1UL << PG_slab | 1UL << PG_active | \
728 1UL << PG_unevictable | __PG_MLOCKED)
731 * Flags checked when a page is prepped for return by the page allocator.
732 * Pages being prepped should not have these flags set. It they are set,
733 * there has been a kernel bug or struct page corruption.
735 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
736 * alloc-free cycle to prevent from reusing the page.
738 #define PAGE_FLAGS_CHECK_AT_PREP \
739 (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
741 #define PAGE_FLAGS_PRIVATE \
742 (1UL << PG_private | 1UL << PG_private_2)
744 * page_has_private - Determine if page has private stuff
745 * @page: The page to be checked
747 * Determine if a page has private stuff, indicating that release routines
748 * should be invoked upon it.
750 static inline int page_has_private(struct page
*page
)
752 return !!(page
->flags
& PAGE_FLAGS_PRIVATE
);
759 #undef PF_NO_COMPOUND
760 #endif /* !__GENERATING_BOUNDS_H */
762 #endif /* PAGE_FLAGS_H */