1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Macros for manipulating and testing page->flags
9 #include <linux/types.h>
10 #include <linux/bug.h>
11 #include <linux/mmdebug.h>
12 #ifndef __GENERATING_BOUNDS_H
13 #include <linux/mm_types.h>
14 #include <generated/bounds.h>
15 #endif /* !__GENERATING_BOUNDS_H */
18 * Various page->flags bits:
20 * PG_reserved is set for special pages, which can never be swapped out. Some
21 * of them might not even exist...
23 * The PG_private bitflag is set on pagecache pages if they contain filesystem
24 * specific data (which is normally at page->private). It can be used by
25 * private allocations for its own usage.
27 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O
28 * and cleared when writeback _starts_ or when read _completes_. PG_writeback
29 * is set before writeback starts and cleared when it finishes.
31 * PG_locked also pins a page in pagecache, and blocks truncation of the file
34 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
37 * PG_uptodate tells whether the page's contents is valid. When a read
38 * completes, the page becomes uptodate, unless a disk I/O error happened.
40 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
41 * file-backed pagecache (see mm/vmscan.c).
43 * PG_error is set to indicate that an I/O error occurred on this page.
45 * PG_arch_1 is an architecture specific page state bit. The generic code
46 * guarantees that this bit is cleared for a page when it first is entered into
49 * PG_highmem pages are not permanently mapped into the kernel virtual address
50 * space, they need to be kmapped separately for doing IO on the pages. The
51 * struct page (these bits with information) are always mapped into kernel
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. */
83 PG_waiters
, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
85 PG_owner_priv_1
, /* Owner use. If pagecache, fs may use*/
88 PG_private
, /* If pagecache, has fs-private data */
89 PG_private_2
, /* If pagecache, has fs aux data */
90 PG_writeback
, /* Page is under writeback */
91 PG_head
, /* A head page */
92 PG_mappedtodisk
, /* Has blocks allocated on-disk */
93 PG_reclaim
, /* To be reclaimed asap */
94 PG_swapbacked
, /* Page is backed by RAM/swap */
95 PG_unevictable
, /* Page is "unevictable" */
97 PG_mlocked
, /* Page is vma mlocked */
99 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
100 PG_uncached
, /* Page has been mapped as uncached */
102 #ifdef CONFIG_MEMORY_FAILURE
103 PG_hwpoison
, /* hardware poisoned page. Don't touch */
105 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
112 PG_checked
= PG_owner_priv_1
,
115 PG_swapcache
= PG_owner_priv_1
, /* Swap page: swp_entry_t in private */
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 /* Pinned in Xen as a read-only pagetable page. */
125 PG_pinned
= PG_owner_priv_1
,
126 /* Pinned as part of domain save (see xen_mm_pin_all()). */
127 PG_savepinned
= PG_dirty
,
128 /* Has a grant mapping of another (foreign) domain's page. */
129 PG_foreign
= PG_owner_priv_1
,
132 PG_slob_free
= PG_private
,
134 /* Compound pages. Stored in first tail page's flags */
135 PG_double_map
= PG_private_2
,
137 /* non-lru isolated movable page */
138 PG_isolated
= PG_reclaim
,
141 #ifndef __GENERATING_BOUNDS_H
143 struct page
; /* forward declaration */
145 static inline struct page
*compound_head(struct page
*page
)
147 unsigned long head
= READ_ONCE(page
->compound_head
);
149 if (unlikely(head
& 1))
150 return (struct page
*) (head
- 1);
154 static __always_inline
int PageTail(struct page
*page
)
156 return READ_ONCE(page
->compound_head
) & 1;
159 static __always_inline
int PageCompound(struct page
*page
)
161 return test_bit(PG_head
, &page
->flags
) || PageTail(page
);
165 * Page flags policies wrt compound pages
168 * the page flag is relevant for small, head and tail pages.
171 * for compound page all operations related to the page flag applied to
175 * for compound page, callers only ever operate on the head page.
178 * modifications of the page flag must be done on small or head pages,
179 * checks can be done on tail pages too.
182 * the page flag is not relevant for compound pages.
184 #define PF_ANY(page, enforce) page
185 #define PF_HEAD(page, enforce) compound_head(page)
186 #define PF_ONLY_HEAD(page, enforce) ({ \
187 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
189 #define PF_NO_TAIL(page, enforce) ({ \
190 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
191 compound_head(page);})
192 #define PF_NO_COMPOUND(page, enforce) ({ \
193 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
197 * Macros to create function definitions for page flags
199 #define TESTPAGEFLAG(uname, lname, policy) \
200 static __always_inline int Page##uname(struct page *page) \
201 { return test_bit(PG_##lname, &policy(page, 0)->flags); }
203 #define SETPAGEFLAG(uname, lname, policy) \
204 static __always_inline void SetPage##uname(struct page *page) \
205 { set_bit(PG_##lname, &policy(page, 1)->flags); }
207 #define CLEARPAGEFLAG(uname, lname, policy) \
208 static __always_inline void ClearPage##uname(struct page *page) \
209 { clear_bit(PG_##lname, &policy(page, 1)->flags); }
211 #define __SETPAGEFLAG(uname, lname, policy) \
212 static __always_inline void __SetPage##uname(struct page *page) \
213 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
215 #define __CLEARPAGEFLAG(uname, lname, policy) \
216 static __always_inline void __ClearPage##uname(struct page *page) \
217 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
219 #define TESTSETFLAG(uname, lname, policy) \
220 static __always_inline int TestSetPage##uname(struct page *page) \
221 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
223 #define TESTCLEARFLAG(uname, lname, policy) \
224 static __always_inline int TestClearPage##uname(struct page *page) \
225 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
227 #define PAGEFLAG(uname, lname, policy) \
228 TESTPAGEFLAG(uname, lname, policy) \
229 SETPAGEFLAG(uname, lname, policy) \
230 CLEARPAGEFLAG(uname, lname, policy)
232 #define __PAGEFLAG(uname, lname, policy) \
233 TESTPAGEFLAG(uname, lname, policy) \
234 __SETPAGEFLAG(uname, lname, policy) \
235 __CLEARPAGEFLAG(uname, lname, policy)
237 #define TESTSCFLAG(uname, lname, policy) \
238 TESTSETFLAG(uname, lname, policy) \
239 TESTCLEARFLAG(uname, lname, policy)
241 #define TESTPAGEFLAG_FALSE(uname) \
242 static inline int Page##uname(const struct page *page) { return 0; }
244 #define SETPAGEFLAG_NOOP(uname) \
245 static inline void SetPage##uname(struct page *page) { }
247 #define CLEARPAGEFLAG_NOOP(uname) \
248 static inline void ClearPage##uname(struct page *page) { }
250 #define __CLEARPAGEFLAG_NOOP(uname) \
251 static inline void __ClearPage##uname(struct page *page) { }
253 #define TESTSETFLAG_FALSE(uname) \
254 static inline int TestSetPage##uname(struct page *page) { return 0; }
256 #define TESTCLEARFLAG_FALSE(uname) \
257 static inline int TestClearPage##uname(struct page *page) { return 0; }
259 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \
260 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
262 #define TESTSCFLAG_FALSE(uname) \
263 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
265 __PAGEFLAG(Locked
, locked
, PF_NO_TAIL
)
266 PAGEFLAG(Waiters
, waiters
, PF_ONLY_HEAD
) __CLEARPAGEFLAG(Waiters
, waiters
, PF_ONLY_HEAD
)
267 PAGEFLAG(Error
, error
, PF_NO_COMPOUND
) TESTCLEARFLAG(Error
, error
, PF_NO_COMPOUND
)
268 PAGEFLAG(Referenced
, referenced
, PF_HEAD
)
269 TESTCLEARFLAG(Referenced
, referenced
, PF_HEAD
)
270 __SETPAGEFLAG(Referenced
, referenced
, PF_HEAD
)
271 PAGEFLAG(Dirty
, dirty
, PF_HEAD
) TESTSCFLAG(Dirty
, dirty
, PF_HEAD
)
272 __CLEARPAGEFLAG(Dirty
, dirty
, PF_HEAD
)
273 PAGEFLAG(LRU
, lru
, PF_HEAD
) __CLEARPAGEFLAG(LRU
, lru
, PF_HEAD
)
274 PAGEFLAG(Active
, active
, PF_HEAD
) __CLEARPAGEFLAG(Active
, active
, PF_HEAD
)
275 TESTCLEARFLAG(Active
, active
, PF_HEAD
)
276 __PAGEFLAG(Slab
, slab
, PF_NO_TAIL
)
277 __PAGEFLAG(SlobFree
, slob_free
, PF_NO_TAIL
)
278 PAGEFLAG(Checked
, checked
, PF_NO_COMPOUND
) /* Used by some filesystems */
281 PAGEFLAG(Pinned
, pinned
, PF_NO_COMPOUND
)
282 TESTSCFLAG(Pinned
, pinned
, PF_NO_COMPOUND
)
283 PAGEFLAG(SavePinned
, savepinned
, PF_NO_COMPOUND
);
284 PAGEFLAG(Foreign
, foreign
, PF_NO_COMPOUND
);
286 PAGEFLAG(Reserved
, reserved
, PF_NO_COMPOUND
)
287 __CLEARPAGEFLAG(Reserved
, reserved
, PF_NO_COMPOUND
)
288 PAGEFLAG(SwapBacked
, swapbacked
, PF_NO_TAIL
)
289 __CLEARPAGEFLAG(SwapBacked
, swapbacked
, PF_NO_TAIL
)
290 __SETPAGEFLAG(SwapBacked
, swapbacked
, PF_NO_TAIL
)
293 * Private page markings that may be used by the filesystem that owns the page
294 * for its own purposes.
295 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
297 PAGEFLAG(Private
, private, PF_ANY
) __SETPAGEFLAG(Private
, private, PF_ANY
)
298 __CLEARPAGEFLAG(Private
, private, PF_ANY
)
299 PAGEFLAG(Private2
, private_2
, PF_ANY
) TESTSCFLAG(Private2
, private_2
, PF_ANY
)
300 PAGEFLAG(OwnerPriv1
, owner_priv_1
, PF_ANY
)
301 TESTCLEARFLAG(OwnerPriv1
, owner_priv_1
, PF_ANY
)
304 * Only test-and-set exist for PG_writeback. The unconditional operators are
305 * risky: they bypass page accounting.
307 TESTPAGEFLAG(Writeback
, writeback
, PF_NO_TAIL
)
308 TESTSCFLAG(Writeback
, writeback
, PF_NO_TAIL
)
309 PAGEFLAG(MappedToDisk
, mappedtodisk
, PF_NO_TAIL
)
311 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
312 PAGEFLAG(Reclaim
, reclaim
, PF_NO_TAIL
)
313 TESTCLEARFLAG(Reclaim
, reclaim
, PF_NO_TAIL
)
314 PAGEFLAG(Readahead
, reclaim
, PF_NO_COMPOUND
)
315 TESTCLEARFLAG(Readahead
, reclaim
, PF_NO_COMPOUND
)
317 #ifdef CONFIG_HIGHMEM
319 * Must use a macro here due to header dependency issues. page_zone() is not
320 * available at this point.
322 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
324 PAGEFLAG_FALSE(HighMem
)
328 static __always_inline
int PageSwapCache(struct page
*page
)
330 #ifdef CONFIG_THP_SWAP
331 page
= compound_head(page
);
333 return PageSwapBacked(page
) && test_bit(PG_swapcache
, &page
->flags
);
336 SETPAGEFLAG(SwapCache
, swapcache
, PF_NO_TAIL
)
337 CLEARPAGEFLAG(SwapCache
, swapcache
, PF_NO_TAIL
)
339 PAGEFLAG_FALSE(SwapCache
)
342 PAGEFLAG(Unevictable
, unevictable
, PF_HEAD
)
343 __CLEARPAGEFLAG(Unevictable
, unevictable
, PF_HEAD
)
344 TESTCLEARFLAG(Unevictable
, unevictable
, PF_HEAD
)
347 PAGEFLAG(Mlocked
, mlocked
, PF_NO_TAIL
)
348 __CLEARPAGEFLAG(Mlocked
, mlocked
, PF_NO_TAIL
)
349 TESTSCFLAG(Mlocked
, mlocked
, PF_NO_TAIL
)
351 PAGEFLAG_FALSE(Mlocked
) __CLEARPAGEFLAG_NOOP(Mlocked
)
352 TESTSCFLAG_FALSE(Mlocked
)
355 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
356 PAGEFLAG(Uncached
, uncached
, PF_NO_COMPOUND
)
358 PAGEFLAG_FALSE(Uncached
)
361 #ifdef CONFIG_MEMORY_FAILURE
362 PAGEFLAG(HWPoison
, hwpoison
, PF_ANY
)
363 TESTSCFLAG(HWPoison
, hwpoison
, PF_ANY
)
364 #define __PG_HWPOISON (1UL << PG_hwpoison)
366 PAGEFLAG_FALSE(HWPoison
)
367 #define __PG_HWPOISON 0
370 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
371 TESTPAGEFLAG(Young
, young
, PF_ANY
)
372 SETPAGEFLAG(Young
, young
, PF_ANY
)
373 TESTCLEARFLAG(Young
, young
, PF_ANY
)
374 PAGEFLAG(Idle
, idle
, PF_ANY
)
378 * On an anonymous page mapped into a user virtual memory area,
379 * page->mapping points to its anon_vma, not to a struct address_space;
380 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
382 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
383 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
384 * bit; and then page->mapping points, not to an anon_vma, but to a private
385 * structure which KSM associates with that merged page. See ksm.h.
387 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
388 * page and then page->mapping points a struct address_space.
390 * Please note that, confusingly, "page_mapping" refers to the inode
391 * address_space which maps the page from disk; whereas "page_mapped"
392 * refers to user virtual address space into which the page is mapped.
394 #define PAGE_MAPPING_ANON 0x1
395 #define PAGE_MAPPING_MOVABLE 0x2
396 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
397 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
399 static __always_inline
int PageMappingFlags(struct page
*page
)
401 return ((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) != 0;
404 static __always_inline
int PageAnon(struct page
*page
)
406 page
= compound_head(page
);
407 return ((unsigned long)page
->mapping
& PAGE_MAPPING_ANON
) != 0;
410 static __always_inline
int __PageMovable(struct page
*page
)
412 return ((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) ==
413 PAGE_MAPPING_MOVABLE
;
418 * A KSM page is one of those write-protected "shared pages" or "merged pages"
419 * which KSM maps into multiple mms, wherever identical anonymous page content
420 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
421 * anon_vma, but to that page's node of the stable tree.
423 static __always_inline
int PageKsm(struct page
*page
)
425 page
= compound_head(page
);
426 return ((unsigned long)page
->mapping
& PAGE_MAPPING_FLAGS
) ==
430 TESTPAGEFLAG_FALSE(Ksm
)
433 u64
stable_page_flags(struct page
*page
);
435 static inline int PageUptodate(struct page
*page
)
438 page
= compound_head(page
);
439 ret
= test_bit(PG_uptodate
, &(page
)->flags
);
441 * Must ensure that the data we read out of the page is loaded
442 * _after_ we've loaded page->flags to check for PageUptodate.
443 * We can skip the barrier if the page is not uptodate, because
444 * we wouldn't be reading anything from it.
446 * See SetPageUptodate() for the other side of the story.
454 static __always_inline
void __SetPageUptodate(struct page
*page
)
456 VM_BUG_ON_PAGE(PageTail(page
), page
);
458 __set_bit(PG_uptodate
, &page
->flags
);
461 static __always_inline
void SetPageUptodate(struct page
*page
)
463 VM_BUG_ON_PAGE(PageTail(page
), page
);
465 * Memory barrier must be issued before setting the PG_uptodate bit,
466 * so that all previous stores issued in order to bring the page
467 * uptodate are actually visible before PageUptodate becomes true.
470 set_bit(PG_uptodate
, &page
->flags
);
473 CLEARPAGEFLAG(Uptodate
, uptodate
, PF_NO_TAIL
)
475 int test_clear_page_writeback(struct page
*page
);
476 int __test_set_page_writeback(struct page
*page
, bool keep_write
);
478 #define test_set_page_writeback(page) \
479 __test_set_page_writeback(page, false)
480 #define test_set_page_writeback_keepwrite(page) \
481 __test_set_page_writeback(page, true)
483 static inline void set_page_writeback(struct page
*page
)
485 test_set_page_writeback(page
);
488 static inline void set_page_writeback_keepwrite(struct page
*page
)
490 test_set_page_writeback_keepwrite(page
);
493 __PAGEFLAG(Head
, head
, PF_ANY
) CLEARPAGEFLAG(Head
, head
, PF_ANY
)
495 static __always_inline
void set_compound_head(struct page
*page
, struct page
*head
)
497 WRITE_ONCE(page
->compound_head
, (unsigned long)head
+ 1);
500 static __always_inline
void clear_compound_head(struct page
*page
)
502 WRITE_ONCE(page
->compound_head
, 0);
505 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
506 static inline void ClearPageCompound(struct page
*page
)
508 BUG_ON(!PageHead(page
));
513 #define PG_head_mask ((1UL << PG_head))
515 #ifdef CONFIG_HUGETLB_PAGE
516 int PageHuge(struct page
*page
);
517 int PageHeadHuge(struct page
*page
);
518 bool page_huge_active(struct page
*page
);
520 TESTPAGEFLAG_FALSE(Huge
)
521 TESTPAGEFLAG_FALSE(HeadHuge
)
523 static inline bool page_huge_active(struct page
*page
)
530 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
532 * PageHuge() only returns true for hugetlbfs pages, but not for
533 * normal or transparent huge pages.
535 * PageTransHuge() returns true for both transparent huge and
536 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
537 * called only in the core VM paths where hugetlbfs pages can't exist.
539 static inline int PageTransHuge(struct page
*page
)
541 VM_BUG_ON_PAGE(PageTail(page
), page
);
542 return PageHead(page
);
546 * PageTransCompound returns true for both transparent huge pages
547 * and hugetlbfs pages, so it should only be called when it's known
548 * that hugetlbfs pages aren't involved.
550 static inline int PageTransCompound(struct page
*page
)
552 return PageCompound(page
);
556 * PageTransCompoundMap is the same as PageTransCompound, but it also
557 * guarantees the primary MMU has the entire compound page mapped
558 * through pmd_trans_huge, which in turn guarantees the secondary MMUs
559 * can also map the entire compound page. This allows the secondary
560 * MMUs to call get_user_pages() only once for each compound page and
561 * to immediately map the entire compound page with a single secondary
562 * MMU fault. If there will be a pmd split later, the secondary MMUs
563 * will get an update through the MMU notifier invalidation through
566 * Unlike PageTransCompound, this is safe to be called only while
567 * split_huge_pmd() cannot run from under us, like if protected by the
568 * MMU notifier, otherwise it may result in page->_mapcount < 0 false
571 static inline int PageTransCompoundMap(struct page
*page
)
573 return PageTransCompound(page
) && atomic_read(&page
->_mapcount
) < 0;
577 * PageTransTail returns true for both transparent huge pages
578 * and hugetlbfs pages, so it should only be called when it's known
579 * that hugetlbfs pages aren't involved.
581 static inline int PageTransTail(struct page
*page
)
583 return PageTail(page
);
587 * PageDoubleMap indicates that the compound page is mapped with PTEs as well
590 * This is required for optimization of rmap operations for THP: we can postpone
591 * per small page mapcount accounting (and its overhead from atomic operations)
592 * until the first PMD split.
594 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
595 * by one. This reference will go away with last compound_mapcount.
597 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
599 static inline int PageDoubleMap(struct page
*page
)
601 return PageHead(page
) && test_bit(PG_double_map
, &page
[1].flags
);
604 static inline void SetPageDoubleMap(struct page
*page
)
606 VM_BUG_ON_PAGE(!PageHead(page
), page
);
607 set_bit(PG_double_map
, &page
[1].flags
);
610 static inline void ClearPageDoubleMap(struct page
*page
)
612 VM_BUG_ON_PAGE(!PageHead(page
), page
);
613 clear_bit(PG_double_map
, &page
[1].flags
);
615 static inline int TestSetPageDoubleMap(struct page
*page
)
617 VM_BUG_ON_PAGE(!PageHead(page
), page
);
618 return test_and_set_bit(PG_double_map
, &page
[1].flags
);
621 static inline int TestClearPageDoubleMap(struct page
*page
)
623 VM_BUG_ON_PAGE(!PageHead(page
), page
);
624 return test_and_clear_bit(PG_double_map
, &page
[1].flags
);
628 TESTPAGEFLAG_FALSE(TransHuge
)
629 TESTPAGEFLAG_FALSE(TransCompound
)
630 TESTPAGEFLAG_FALSE(TransCompoundMap
)
631 TESTPAGEFLAG_FALSE(TransTail
)
632 PAGEFLAG_FALSE(DoubleMap
)
633 TESTSETFLAG_FALSE(DoubleMap
)
634 TESTCLEARFLAG_FALSE(DoubleMap
)
638 * For pages that are never mapped to userspace, page->mapcount may be
639 * used for storing extra information about page type. Any value used
640 * for this purpose must be <= -2, but it's better start not too close
641 * to -2 so that an underflow of the page_mapcount() won't be mistaken
642 * for a special page.
644 #define PAGE_MAPCOUNT_OPS(uname, lname) \
645 static __always_inline int Page##uname(struct page *page) \
647 return atomic_read(&page->_mapcount) == \
648 PAGE_##lname##_MAPCOUNT_VALUE; \
650 static __always_inline void __SetPage##uname(struct page *page) \
652 VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page); \
653 atomic_set(&page->_mapcount, PAGE_##lname##_MAPCOUNT_VALUE); \
655 static __always_inline void __ClearPage##uname(struct page *page) \
657 VM_BUG_ON_PAGE(!Page##uname(page), page); \
658 atomic_set(&page->_mapcount, -1); \
662 * PageBuddy() indicate that the page is free and in the buddy system
663 * (see mm/page_alloc.c).
665 #define PAGE_BUDDY_MAPCOUNT_VALUE (-128)
666 PAGE_MAPCOUNT_OPS(Buddy
, BUDDY
)
669 * PageBalloon() is set on pages that are on the balloon page list
670 * (see mm/balloon_compaction.c).
672 #define PAGE_BALLOON_MAPCOUNT_VALUE (-256)
673 PAGE_MAPCOUNT_OPS(Balloon
, BALLOON
)
676 * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on
677 * pages allocated with __GFP_ACCOUNT. It gets cleared on page free.
679 #define PAGE_KMEMCG_MAPCOUNT_VALUE (-512)
680 PAGE_MAPCOUNT_OPS(Kmemcg
, KMEMCG
)
682 extern bool is_free_buddy_page(struct page
*page
);
684 __PAGEFLAG(Isolated
, isolated
, PF_ANY
);
687 * If network-based swap is enabled, sl*b must keep track of whether pages
688 * were allocated from pfmemalloc reserves.
690 static inline int PageSlabPfmemalloc(struct page
*page
)
692 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
693 return PageActive(page
);
696 static inline void SetPageSlabPfmemalloc(struct page
*page
)
698 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
702 static inline void __ClearPageSlabPfmemalloc(struct page
*page
)
704 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
705 __ClearPageActive(page
);
708 static inline void ClearPageSlabPfmemalloc(struct page
*page
)
710 VM_BUG_ON_PAGE(!PageSlab(page
), page
);
711 ClearPageActive(page
);
715 #define __PG_MLOCKED (1UL << PG_mlocked)
717 #define __PG_MLOCKED 0
721 * Flags checked when a page is freed. Pages being freed should not have
722 * these flags set. It they are, there is a problem.
724 #define PAGE_FLAGS_CHECK_AT_FREE \
725 (1UL << PG_lru | 1UL << PG_locked | \
726 1UL << PG_private | 1UL << PG_private_2 | \
727 1UL << PG_writeback | 1UL << PG_reserved | \
728 1UL << PG_slab | 1UL << PG_active | \
729 1UL << PG_unevictable | __PG_MLOCKED)
732 * Flags checked when a page is prepped for return by the page allocator.
733 * Pages being prepped should not have these flags set. It they are set,
734 * there has been a kernel bug or struct page corruption.
736 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
737 * alloc-free cycle to prevent from reusing the page.
739 #define PAGE_FLAGS_CHECK_AT_PREP \
740 (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
742 #define PAGE_FLAGS_PRIVATE \
743 (1UL << PG_private | 1UL << PG_private_2)
745 * page_has_private - Determine if page has private stuff
746 * @page: The page to be checked
748 * Determine if a page has private stuff, indicating that release routines
749 * should be invoked upon it.
751 static inline int page_has_private(struct page
*page
)
753 return !!(page
->flags
& PAGE_FLAGS_PRIVATE
);
760 #undef PF_NO_COMPOUND
761 #endif /* !__GENERATING_BOUNDS_H */
763 #endif /* PAGE_FLAGS_H */