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_hwpoison indicates that a page got corrupted in hardware and contains
50 * data with incorrect ECC bits that triggered a machine check. Accessing is
51 * not safe since it may cause another machine check. Don't touch!
55 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
56 * locked- and dirty-page accounting.
58 * The page flags field is split into two parts, the main flags area
59 * which extends from the low bits upwards, and the fields area which
60 * extends from the high bits downwards.
62 * | FIELD | ... | FLAGS |
66 * The fields area is reserved for fields mapping zone, node (for NUMA) and
67 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like
68 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
71 PG_locked, /* Page is locked. Don't touch. */
78 PG_waiters, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
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 PG_head, /* A head page */
88 PG_mappedtodisk, /* Has blocks allocated on-disk */
89 PG_reclaim, /* To be reclaimed asap */
90 PG_swapbacked, /* Page is backed by RAM/swap */
91 PG_unevictable, /* Page is "unevictable" */
93 PG_mlocked, /* Page is vma mlocked */
95 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
96 PG_uncached, /* Page has been mapped as uncached */
98 #ifdef CONFIG_MEMORY_FAILURE
99 PG_hwpoison, /* hardware poisoned page. Don't touch */
101 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
108 PG_checked = PG_owner_priv_1,
111 PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */
113 /* Two page bits are conscripted by FS-Cache to maintain local caching
114 * state. These bits are set on pages belonging to the netfs's inodes
115 * when those inodes are being locally cached.
117 PG_fscache = PG_private_2, /* page backed by cache */
120 /* Pinned in Xen as a read-only pagetable page. */
121 PG_pinned = PG_owner_priv_1,
122 /* Pinned as part of domain save (see xen_mm_pin_all()). */
123 PG_savepinned = PG_dirty,
124 /* Has a grant mapping of another (foreign) domain's page. */
125 PG_foreign = PG_owner_priv_1,
128 PG_slob_free = PG_private,
130 /* Compound pages. Stored in first tail page's flags */
131 PG_double_map = PG_private_2,
133 /* non-lru isolated movable page */
134 PG_isolated = PG_reclaim,
137 #ifndef __GENERATING_BOUNDS_H
139 struct page; /* forward declaration */
141 static inline struct page *compound_head(struct page *page)
143 unsigned long head = READ_ONCE(page->compound_head);
145 if (unlikely(head & 1))
146 return (struct page *) (head - 1);
150 static __always_inline int PageTail(struct page *page)
152 return READ_ONCE(page->compound_head) & 1;
155 static __always_inline int PageCompound(struct page *page)
157 return test_bit(PG_head, &page->flags) || PageTail(page);
160 #define PAGE_POISON_PATTERN -1l
161 static inline int PagePoisoned(const struct page *page)
163 return page->flags == PAGE_POISON_PATTERN;
166 #ifdef CONFIG_DEBUG_VM
167 void page_init_poison(struct page *page, size_t size);
169 static inline void page_init_poison(struct page *page, size_t size)
175 * Page flags policies wrt compound pages
178 * check if this struct page poisoned/uninitialized
181 * the page flag is relevant for small, head and tail pages.
184 * for compound page all operations related to the page flag applied to
188 * for compound page, callers only ever operate on the head page.
191 * modifications of the page flag must be done on small or head pages,
192 * checks can be done on tail pages too.
195 * the page flag is not relevant for compound pages.
197 #define PF_POISONED_CHECK(page) ({ \
198 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \
200 #define PF_ANY(page, enforce) PF_POISONED_CHECK(page)
201 #define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page))
202 #define PF_ONLY_HEAD(page, enforce) ({ \
203 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
204 PF_POISONED_CHECK(page); })
205 #define PF_NO_TAIL(page, enforce) ({ \
206 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
207 PF_POISONED_CHECK(compound_head(page)); })
208 #define PF_NO_COMPOUND(page, enforce) ({ \
209 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
210 PF_POISONED_CHECK(page); })
213 * Macros to create function definitions for page flags
215 #define TESTPAGEFLAG(uname, lname, policy) \
216 static __always_inline int Page##uname(struct page *page) \
217 { return test_bit(PG_##lname, &policy(page, 0)->flags); }
219 #define SETPAGEFLAG(uname, lname, policy) \
220 static __always_inline void SetPage##uname(struct page *page) \
221 { set_bit(PG_##lname, &policy(page, 1)->flags); }
223 #define CLEARPAGEFLAG(uname, lname, policy) \
224 static __always_inline void ClearPage##uname(struct page *page) \
225 { clear_bit(PG_##lname, &policy(page, 1)->flags); }
227 #define __SETPAGEFLAG(uname, lname, policy) \
228 static __always_inline void __SetPage##uname(struct page *page) \
229 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
231 #define __CLEARPAGEFLAG(uname, lname, policy) \
232 static __always_inline void __ClearPage##uname(struct page *page) \
233 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
235 #define TESTSETFLAG(uname, lname, policy) \
236 static __always_inline int TestSetPage##uname(struct page *page) \
237 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
239 #define TESTCLEARFLAG(uname, lname, policy) \
240 static __always_inline int TestClearPage##uname(struct page *page) \
241 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
243 #define PAGEFLAG(uname, lname, policy) \
244 TESTPAGEFLAG(uname, lname, policy) \
245 SETPAGEFLAG(uname, lname, policy) \
246 CLEARPAGEFLAG(uname, lname, policy)
248 #define __PAGEFLAG(uname, lname, policy) \
249 TESTPAGEFLAG(uname, lname, policy) \
250 __SETPAGEFLAG(uname, lname, policy) \
251 __CLEARPAGEFLAG(uname, lname, policy)
253 #define TESTSCFLAG(uname, lname, policy) \
254 TESTSETFLAG(uname, lname, policy) \
255 TESTCLEARFLAG(uname, lname, policy)
257 #define TESTPAGEFLAG_FALSE(uname) \
258 static inline int Page##uname(const struct page *page) { return 0; }
260 #define SETPAGEFLAG_NOOP(uname) \
261 static inline void SetPage##uname(struct page *page) { }
263 #define CLEARPAGEFLAG_NOOP(uname) \
264 static inline void ClearPage##uname(struct page *page) { }
266 #define __CLEARPAGEFLAG_NOOP(uname) \
267 static inline void __ClearPage##uname(struct page *page) { }
269 #define TESTSETFLAG_FALSE(uname) \
270 static inline int TestSetPage##uname(struct page *page) { return 0; }
272 #define TESTCLEARFLAG_FALSE(uname) \
273 static inline int TestClearPage##uname(struct page *page) { return 0; }
275 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \
276 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
278 #define TESTSCFLAG_FALSE(uname) \
279 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
281 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
282 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
283 PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND)
284 PAGEFLAG(Referenced, referenced, PF_HEAD)
285 TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
286 __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
287 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
288 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
289 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
290 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
291 TESTCLEARFLAG(Active, active, PF_HEAD)
292 PAGEFLAG(Workingset, workingset, PF_HEAD)
293 TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
294 __PAGEFLAG(Slab, slab, PF_NO_TAIL)
295 __PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
296 PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
299 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
300 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
301 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
302 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
304 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
305 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
306 __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
307 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
308 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
309 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
312 * Private page markings that may be used by the filesystem that owns the page
313 * for its own purposes.
314 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
316 PAGEFLAG(Private, private, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY)
317 __CLEARPAGEFLAG(Private, private, PF_ANY)
318 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
319 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
320 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
323 * Only test-and-set exist for PG_writeback. The unconditional operators are
324 * risky: they bypass page accounting.
326 TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL)
327 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)
328 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
330 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
331 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
332 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
333 PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
334 TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
336 #ifdef CONFIG_HIGHMEM
338 * Must use a macro here due to header dependency issues. page_zone() is not
339 * available at this point.
341 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
343 PAGEFLAG_FALSE(HighMem)
347 static __always_inline int PageSwapCache(struct page *page)
349 #ifdef CONFIG_THP_SWAP
350 page = compound_head(page);
352 return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags);
355 SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
356 CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
358 PAGEFLAG_FALSE(SwapCache)
361 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
362 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
363 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
366 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
367 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
368 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
370 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
371 TESTSCFLAG_FALSE(Mlocked)
374 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
375 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
377 PAGEFLAG_FALSE(Uncached)
380 #ifdef CONFIG_MEMORY_FAILURE
381 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
382 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
383 #define __PG_HWPOISON (1UL << PG_hwpoison)
384 extern bool set_hwpoison_free_buddy_page(struct page *page);
386 PAGEFLAG_FALSE(HWPoison)
387 static inline bool set_hwpoison_free_buddy_page(struct page *page)
391 #define __PG_HWPOISON 0
394 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
395 TESTPAGEFLAG(Young, young, PF_ANY)
396 SETPAGEFLAG(Young, young, PF_ANY)
397 TESTCLEARFLAG(Young, young, PF_ANY)
398 PAGEFLAG(Idle, idle, PF_ANY)
402 * On an anonymous page mapped into a user virtual memory area,
403 * page->mapping points to its anon_vma, not to a struct address_space;
404 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
406 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
407 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
408 * bit; and then page->mapping points, not to an anon_vma, but to a private
409 * structure which KSM associates with that merged page. See ksm.h.
411 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
412 * page and then page->mapping points a struct address_space.
414 * Please note that, confusingly, "page_mapping" refers to the inode
415 * address_space which maps the page from disk; whereas "page_mapped"
416 * refers to user virtual address space into which the page is mapped.
418 #define PAGE_MAPPING_ANON 0x1
419 #define PAGE_MAPPING_MOVABLE 0x2
420 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
421 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
423 static __always_inline int PageMappingFlags(struct page *page)
425 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
428 static __always_inline int PageAnon(struct page *page)
430 page = compound_head(page);
431 return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
434 static __always_inline int __PageMovable(struct page *page)
436 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
437 PAGE_MAPPING_MOVABLE;
442 * A KSM page is one of those write-protected "shared pages" or "merged pages"
443 * which KSM maps into multiple mms, wherever identical anonymous page content
444 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
445 * anon_vma, but to that page's node of the stable tree.
447 static __always_inline int PageKsm(struct page *page)
449 page = compound_head(page);
450 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
454 TESTPAGEFLAG_FALSE(Ksm)
457 u64 stable_page_flags(struct page *page);
459 static inline int PageUptodate(struct page *page)
462 page = compound_head(page);
463 ret = test_bit(PG_uptodate, &(page)->flags);
465 * Must ensure that the data we read out of the page is loaded
466 * _after_ we've loaded page->flags to check for PageUptodate.
467 * We can skip the barrier if the page is not uptodate, because
468 * we wouldn't be reading anything from it.
470 * See SetPageUptodate() for the other side of the story.
478 static __always_inline void __SetPageUptodate(struct page *page)
480 VM_BUG_ON_PAGE(PageTail(page), page);
482 __set_bit(PG_uptodate, &page->flags);
485 static __always_inline void SetPageUptodate(struct page *page)
487 VM_BUG_ON_PAGE(PageTail(page), page);
489 * Memory barrier must be issued before setting the PG_uptodate bit,
490 * so that all previous stores issued in order to bring the page
491 * uptodate are actually visible before PageUptodate becomes true.
494 set_bit(PG_uptodate, &page->flags);
497 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
499 int test_clear_page_writeback(struct page *page);
500 int __test_set_page_writeback(struct page *page, bool keep_write);
502 #define test_set_page_writeback(page) \
503 __test_set_page_writeback(page, false)
504 #define test_set_page_writeback_keepwrite(page) \
505 __test_set_page_writeback(page, true)
507 static inline void set_page_writeback(struct page *page)
509 test_set_page_writeback(page);
512 static inline void set_page_writeback_keepwrite(struct page *page)
514 test_set_page_writeback_keepwrite(page);
517 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
519 static __always_inline void set_compound_head(struct page *page, struct page *head)
521 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
524 static __always_inline void clear_compound_head(struct page *page)
526 WRITE_ONCE(page->compound_head, 0);
529 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
530 static inline void ClearPageCompound(struct page *page)
532 BUG_ON(!PageHead(page));
537 #define PG_head_mask ((1UL << PG_head))
539 #ifdef CONFIG_HUGETLB_PAGE
540 int PageHuge(struct page *page);
541 int PageHeadHuge(struct page *page);
542 bool page_huge_active(struct page *page);
544 TESTPAGEFLAG_FALSE(Huge)
545 TESTPAGEFLAG_FALSE(HeadHuge)
547 static inline bool page_huge_active(struct page *page)
554 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
556 * PageHuge() only returns true for hugetlbfs pages, but not for
557 * normal or transparent huge pages.
559 * PageTransHuge() returns true for both transparent huge and
560 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
561 * called only in the core VM paths where hugetlbfs pages can't exist.
563 static inline int PageTransHuge(struct page *page)
565 VM_BUG_ON_PAGE(PageTail(page), page);
566 return PageHead(page);
570 * PageTransCompound returns true for both transparent huge pages
571 * and hugetlbfs pages, so it should only be called when it's known
572 * that hugetlbfs pages aren't involved.
574 static inline int PageTransCompound(struct page *page)
576 return PageCompound(page);
580 * PageTransCompoundMap is the same as PageTransCompound, but it also
581 * guarantees the primary MMU has the entire compound page mapped
582 * through pmd_trans_huge, which in turn guarantees the secondary MMUs
583 * can also map the entire compound page. This allows the secondary
584 * MMUs to call get_user_pages() only once for each compound page and
585 * to immediately map the entire compound page with a single secondary
586 * MMU fault. If there will be a pmd split later, the secondary MMUs
587 * will get an update through the MMU notifier invalidation through
590 * Unlike PageTransCompound, this is safe to be called only while
591 * split_huge_pmd() cannot run from under us, like if protected by the
592 * MMU notifier, otherwise it may result in page->_mapcount < 0 false
595 static inline int PageTransCompoundMap(struct page *page)
597 return PageTransCompound(page) && atomic_read(&page->_mapcount) < 0;
601 * PageTransTail returns true for both transparent huge pages
602 * and hugetlbfs pages, so it should only be called when it's known
603 * that hugetlbfs pages aren't involved.
605 static inline int PageTransTail(struct page *page)
607 return PageTail(page);
611 * PageDoubleMap indicates that the compound page is mapped with PTEs as well
614 * This is required for optimization of rmap operations for THP: we can postpone
615 * per small page mapcount accounting (and its overhead from atomic operations)
616 * until the first PMD split.
618 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
619 * by one. This reference will go away with last compound_mapcount.
621 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
623 static inline int PageDoubleMap(struct page *page)
625 return PageHead(page) && test_bit(PG_double_map, &page[1].flags);
628 static inline void SetPageDoubleMap(struct page *page)
630 VM_BUG_ON_PAGE(!PageHead(page), page);
631 set_bit(PG_double_map, &page[1].flags);
634 static inline void ClearPageDoubleMap(struct page *page)
636 VM_BUG_ON_PAGE(!PageHead(page), page);
637 clear_bit(PG_double_map, &page[1].flags);
639 static inline int TestSetPageDoubleMap(struct page *page)
641 VM_BUG_ON_PAGE(!PageHead(page), page);
642 return test_and_set_bit(PG_double_map, &page[1].flags);
645 static inline int TestClearPageDoubleMap(struct page *page)
647 VM_BUG_ON_PAGE(!PageHead(page), page);
648 return test_and_clear_bit(PG_double_map, &page[1].flags);
652 TESTPAGEFLAG_FALSE(TransHuge)
653 TESTPAGEFLAG_FALSE(TransCompound)
654 TESTPAGEFLAG_FALSE(TransCompoundMap)
655 TESTPAGEFLAG_FALSE(TransTail)
656 PAGEFLAG_FALSE(DoubleMap)
657 TESTSETFLAG_FALSE(DoubleMap)
658 TESTCLEARFLAG_FALSE(DoubleMap)
662 * For pages that are never mapped to userspace (and aren't PageSlab),
663 * page_type may be used. Because it is initialised to -1, we invert the
664 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
665 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
666 * low bits so that an underflow or overflow of page_mapcount() won't be
667 * mistaken for a page type value.
670 #define PAGE_TYPE_BASE 0xf0000000
671 /* Reserve 0x0000007f to catch underflows of page_mapcount */
672 #define PG_buddy 0x00000080
673 #define PG_balloon 0x00000100
674 #define PG_kmemcg 0x00000200
675 #define PG_table 0x00000400
677 #define PageType(page, flag) \
678 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
680 #define PAGE_TYPE_OPS(uname, lname) \
681 static __always_inline int Page##uname(struct page *page) \
683 return PageType(page, PG_##lname); \
685 static __always_inline void __SetPage##uname(struct page *page) \
687 VM_BUG_ON_PAGE(!PageType(page, 0), page); \
688 page->page_type &= ~PG_##lname; \
690 static __always_inline void __ClearPage##uname(struct page *page) \
692 VM_BUG_ON_PAGE(!Page##uname(page), page); \
693 page->page_type |= PG_##lname; \
697 * PageBuddy() indicates that the page is free and in the buddy system
698 * (see mm/page_alloc.c).
700 PAGE_TYPE_OPS(Buddy, buddy)
703 * PageBalloon() is true for pages that are on the balloon page list
704 * (see mm/balloon_compaction.c).
706 PAGE_TYPE_OPS(Balloon, balloon)
709 * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on
710 * pages allocated with __GFP_ACCOUNT. It gets cleared on page free.
712 PAGE_TYPE_OPS(Kmemcg, kmemcg)
715 * Marks pages in use as page tables.
717 PAGE_TYPE_OPS(Table, table)
719 extern bool is_free_buddy_page(struct page *page);
721 __PAGEFLAG(Isolated, isolated, PF_ANY);
724 * If network-based swap is enabled, sl*b must keep track of whether pages
725 * were allocated from pfmemalloc reserves.
727 static inline int PageSlabPfmemalloc(struct page *page)
729 VM_BUG_ON_PAGE(!PageSlab(page), page);
730 return PageActive(page);
733 static inline void SetPageSlabPfmemalloc(struct page *page)
735 VM_BUG_ON_PAGE(!PageSlab(page), page);
739 static inline void __ClearPageSlabPfmemalloc(struct page *page)
741 VM_BUG_ON_PAGE(!PageSlab(page), page);
742 __ClearPageActive(page);
745 static inline void ClearPageSlabPfmemalloc(struct page *page)
747 VM_BUG_ON_PAGE(!PageSlab(page), page);
748 ClearPageActive(page);
752 #define __PG_MLOCKED (1UL << PG_mlocked)
754 #define __PG_MLOCKED 0
758 * Flags checked when a page is freed. Pages being freed should not have
759 * these flags set. It they are, there is a problem.
761 #define PAGE_FLAGS_CHECK_AT_FREE \
762 (1UL << PG_lru | 1UL << PG_locked | \
763 1UL << PG_private | 1UL << PG_private_2 | \
764 1UL << PG_writeback | 1UL << PG_reserved | \
765 1UL << PG_slab | 1UL << PG_active | \
766 1UL << PG_unevictable | __PG_MLOCKED)
769 * Flags checked when a page is prepped for return by the page allocator.
770 * Pages being prepped should not have these flags set. It they are set,
771 * there has been a kernel bug or struct page corruption.
773 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
774 * alloc-free cycle to prevent from reusing the page.
776 #define PAGE_FLAGS_CHECK_AT_PREP \
777 (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
779 #define PAGE_FLAGS_PRIVATE \
780 (1UL << PG_private | 1UL << PG_private_2)
782 * page_has_private - Determine if page has private stuff
783 * @page: The page to be checked
785 * Determine if a page has private stuff, indicating that release routines
786 * should be invoked upon it.
788 static inline int page_has_private(struct page *page)
790 return !!(page->flags & PAGE_FLAGS_PRIVATE);
797 #undef PF_NO_COMPOUND
798 #endif /* !__GENERATING_BOUNDS_H */
800 #endif /* PAGE_FLAGS_H */