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 PG_head, /* A head page */
90 PG_swapcache, /* Swap page: swp_entry_t in private */
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 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
107 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
114 PG_checked = PG_owner_priv_1,
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,
134 #ifndef __GENERATING_BOUNDS_H
136 struct page; /* forward declaration */
138 static inline struct page *compound_head(struct page *page)
140 unsigned long head = READ_ONCE(page->compound_head);
142 if (unlikely(head & 1))
143 return (struct page *) (head - 1);
147 static inline int PageTail(struct page *page)
149 return READ_ONCE(page->compound_head) & 1;
152 static inline int PageCompound(struct page *page)
154 return test_bit(PG_head, &page->flags) || PageTail(page);
158 * Page flags policies wrt compound pages
161 * the page flag is relevant for small, head and tail pages.
164 * for compound page all operations related to the page flag applied to
168 * modifications of the page flag must be done on small or head pages,
169 * checks can be done on tail pages too.
172 * the page flag is not relevant for compound pages.
174 #define PF_ANY(page, enforce) page
175 #define PF_HEAD(page, enforce) compound_head(page)
176 #define PF_NO_TAIL(page, enforce) ({ \
177 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
178 compound_head(page);})
179 #define PF_NO_COMPOUND(page, enforce) ({ \
180 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
184 * Macros to create function definitions for page flags
186 #define TESTPAGEFLAG(uname, lname, policy) \
187 static inline int Page##uname(struct page *page) \
188 { return test_bit(PG_##lname, &policy(page, 0)->flags); }
190 #define SETPAGEFLAG(uname, lname, policy) \
191 static inline void SetPage##uname(struct page *page) \
192 { set_bit(PG_##lname, &policy(page, 1)->flags); }
194 #define CLEARPAGEFLAG(uname, lname, policy) \
195 static inline void ClearPage##uname(struct page *page) \
196 { clear_bit(PG_##lname, &policy(page, 1)->flags); }
198 #define __SETPAGEFLAG(uname, lname, policy) \
199 static inline void __SetPage##uname(struct page *page) \
200 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
202 #define __CLEARPAGEFLAG(uname, lname, policy) \
203 static inline void __ClearPage##uname(struct page *page) \
204 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
206 #define TESTSETFLAG(uname, lname, policy) \
207 static inline int TestSetPage##uname(struct page *page) \
208 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
210 #define TESTCLEARFLAG(uname, lname, policy) \
211 static inline int TestClearPage##uname(struct page *page) \
212 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
214 #define __TESTCLEARFLAG(uname, lname, policy) \
215 static inline int __TestClearPage##uname(struct page *page) \
216 { return __test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
218 #define PAGEFLAG(uname, lname, policy) \
219 TESTPAGEFLAG(uname, lname, policy) \
220 SETPAGEFLAG(uname, lname, policy) \
221 CLEARPAGEFLAG(uname, lname, policy)
223 #define __PAGEFLAG(uname, lname, policy) \
224 TESTPAGEFLAG(uname, lname, policy) \
225 __SETPAGEFLAG(uname, lname, policy) \
226 __CLEARPAGEFLAG(uname, lname, policy)
228 #define TESTSCFLAG(uname, lname, policy) \
229 TESTSETFLAG(uname, lname, policy) \
230 TESTCLEARFLAG(uname, lname, policy)
232 #define TESTPAGEFLAG_FALSE(uname) \
233 static inline int Page##uname(const struct page *page) { return 0; }
235 #define SETPAGEFLAG_NOOP(uname) \
236 static inline void SetPage##uname(struct page *page) { }
238 #define CLEARPAGEFLAG_NOOP(uname) \
239 static inline void ClearPage##uname(struct page *page) { }
241 #define __CLEARPAGEFLAG_NOOP(uname) \
242 static inline void __ClearPage##uname(struct page *page) { }
244 #define TESTSETFLAG_FALSE(uname) \
245 static inline int TestSetPage##uname(struct page *page) { return 0; }
247 #define TESTCLEARFLAG_FALSE(uname) \
248 static inline int TestClearPage##uname(struct page *page) { return 0; }
250 #define __TESTCLEARFLAG_FALSE(uname) \
251 static inline int __TestClearPage##uname(struct page *page) { return 0; }
253 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \
254 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
256 #define TESTSCFLAG_FALSE(uname) \
257 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
259 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
260 PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND)
261 PAGEFLAG(Referenced, referenced, PF_HEAD)
262 TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
263 __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
264 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
265 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
266 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
267 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
268 TESTCLEARFLAG(Active, active, PF_HEAD)
269 __PAGEFLAG(Slab, slab, PF_NO_TAIL)
270 __PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
271 PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
274 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
275 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
276 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
277 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
279 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
280 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
281 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
282 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
283 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
286 * Private page markings that may be used by the filesystem that owns the page
287 * for its own purposes.
288 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
290 PAGEFLAG(Private, private, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY)
291 __CLEARPAGEFLAG(Private, private, PF_ANY)
292 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
293 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
294 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
297 * Only test-and-set exist for PG_writeback. The unconditional operators are
298 * risky: they bypass page accounting.
300 TESTPAGEFLAG(Writeback, writeback, PF_NO_COMPOUND)
301 TESTSCFLAG(Writeback, writeback, PF_NO_COMPOUND)
302 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_COMPOUND)
304 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
305 PAGEFLAG(Reclaim, reclaim, PF_NO_COMPOUND)
306 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_COMPOUND)
307 PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
308 TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
310 #ifdef CONFIG_HIGHMEM
312 * Must use a macro here due to header dependency issues. page_zone() is not
313 * available at this point.
315 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
317 PAGEFLAG_FALSE(HighMem)
321 PAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND)
323 PAGEFLAG_FALSE(SwapCache)
326 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
327 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
328 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
331 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
332 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
333 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
334 __TESTCLEARFLAG(Mlocked, mlocked, PF_NO_TAIL)
336 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
337 TESTSCFLAG_FALSE(Mlocked) __TESTCLEARFLAG_FALSE(Mlocked)
340 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
341 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
343 PAGEFLAG_FALSE(Uncached)
346 #ifdef CONFIG_MEMORY_FAILURE
347 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
348 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
349 #define __PG_HWPOISON (1UL << PG_hwpoison)
351 PAGEFLAG_FALSE(HWPoison)
352 #define __PG_HWPOISON 0
355 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
356 TESTPAGEFLAG(Young, young, PF_ANY)
357 SETPAGEFLAG(Young, young, PF_ANY)
358 TESTCLEARFLAG(Young, young, PF_ANY)
359 PAGEFLAG(Idle, idle, PF_ANY)
363 * On an anonymous page mapped into a user virtual memory area,
364 * page->mapping points to its anon_vma, not to a struct address_space;
365 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
367 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
368 * the PAGE_MAPPING_KSM bit may be set along with the PAGE_MAPPING_ANON bit;
369 * and then page->mapping points, not to an anon_vma, but to a private
370 * structure which KSM associates with that merged page. See ksm.h.
372 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is currently never used.
374 * Please note that, confusingly, "page_mapping" refers to the inode
375 * address_space which maps the page from disk; whereas "page_mapped"
376 * refers to user virtual address space into which the page is mapped.
378 #define PAGE_MAPPING_ANON 1
379 #define PAGE_MAPPING_KSM 2
380 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM)
382 static inline int PageAnon(struct page *page)
384 return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
389 * A KSM page is one of those write-protected "shared pages" or "merged pages"
390 * which KSM maps into multiple mms, wherever identical anonymous page content
391 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
392 * anon_vma, but to that page's node of the stable tree.
394 static inline int PageKsm(struct page *page)
396 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
397 (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
400 TESTPAGEFLAG_FALSE(Ksm)
403 u64 stable_page_flags(struct page *page);
405 static inline int PageUptodate(struct page *page)
407 int ret = test_bit(PG_uptodate, &(page)->flags);
410 * Must ensure that the data we read out of the page is loaded
411 * _after_ we've loaded page->flags to check for PageUptodate.
412 * We can skip the barrier if the page is not uptodate, because
413 * we wouldn't be reading anything from it.
415 * See SetPageUptodate() for the other side of the story.
423 static inline void __SetPageUptodate(struct page *page)
426 __set_bit(PG_uptodate, &page->flags);
429 static inline void SetPageUptodate(struct page *page)
432 * Memory barrier must be issued before setting the PG_uptodate bit,
433 * so that all previous stores issued in order to bring the page
434 * uptodate are actually visible before PageUptodate becomes true.
437 set_bit(PG_uptodate, &page->flags);
440 CLEARPAGEFLAG(Uptodate, uptodate, PF_ANY)
442 int test_clear_page_writeback(struct page *page);
443 int __test_set_page_writeback(struct page *page, bool keep_write);
445 #define test_set_page_writeback(page) \
446 __test_set_page_writeback(page, false)
447 #define test_set_page_writeback_keepwrite(page) \
448 __test_set_page_writeback(page, true)
450 static inline void set_page_writeback(struct page *page)
452 test_set_page_writeback(page);
455 static inline void set_page_writeback_keepwrite(struct page *page)
457 test_set_page_writeback_keepwrite(page);
460 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
462 static inline void set_compound_head(struct page *page, struct page *head)
464 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
467 static inline void clear_compound_head(struct page *page)
469 WRITE_ONCE(page->compound_head, 0);
472 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
473 static inline void ClearPageCompound(struct page *page)
475 BUG_ON(!PageHead(page));
480 #define PG_head_mask ((1L << PG_head))
482 #ifdef CONFIG_HUGETLB_PAGE
483 int PageHuge(struct page *page);
484 int PageHeadHuge(struct page *page);
485 bool page_huge_active(struct page *page);
487 TESTPAGEFLAG_FALSE(Huge)
488 TESTPAGEFLAG_FALSE(HeadHuge)
490 static inline bool page_huge_active(struct page *page)
497 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
499 * PageHuge() only returns true for hugetlbfs pages, but not for
500 * normal or transparent huge pages.
502 * PageTransHuge() returns true for both transparent huge and
503 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
504 * called only in the core VM paths where hugetlbfs pages can't exist.
506 static inline int PageTransHuge(struct page *page)
508 VM_BUG_ON_PAGE(PageTail(page), page);
509 return PageHead(page);
513 * PageTransCompound returns true for both transparent huge pages
514 * and hugetlbfs pages, so it should only be called when it's known
515 * that hugetlbfs pages aren't involved.
517 static inline int PageTransCompound(struct page *page)
519 return PageCompound(page);
523 * PageTransTail returns true for both transparent huge pages
524 * and hugetlbfs pages, so it should only be called when it's known
525 * that hugetlbfs pages aren't involved.
527 static inline int PageTransTail(struct page *page)
529 return PageTail(page);
533 TESTPAGEFLAG_FALSE(TransHuge)
534 TESTPAGEFLAG_FALSE(TransCompound)
535 TESTPAGEFLAG_FALSE(TransTail)
539 * PageBuddy() indicate that the page is free and in the buddy system
540 * (see mm/page_alloc.c).
542 * PAGE_BUDDY_MAPCOUNT_VALUE must be <= -2 but better not too close to
543 * -2 so that an underflow of the page_mapcount() won't be mistaken
544 * for a genuine PAGE_BUDDY_MAPCOUNT_VALUE. -128 can be created very
545 * efficiently by most CPU architectures.
547 #define PAGE_BUDDY_MAPCOUNT_VALUE (-128)
549 static inline int PageBuddy(struct page *page)
551 return atomic_read(&page->_mapcount) == PAGE_BUDDY_MAPCOUNT_VALUE;
554 static inline void __SetPageBuddy(struct page *page)
556 VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
557 atomic_set(&page->_mapcount, PAGE_BUDDY_MAPCOUNT_VALUE);
560 static inline void __ClearPageBuddy(struct page *page)
562 VM_BUG_ON_PAGE(!PageBuddy(page), page);
563 atomic_set(&page->_mapcount, -1);
566 #define PAGE_BALLOON_MAPCOUNT_VALUE (-256)
568 static inline int PageBalloon(struct page *page)
570 return atomic_read(&page->_mapcount) == PAGE_BALLOON_MAPCOUNT_VALUE;
573 static inline void __SetPageBalloon(struct page *page)
575 VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
576 atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE);
579 static inline void __ClearPageBalloon(struct page *page)
581 VM_BUG_ON_PAGE(!PageBalloon(page), page);
582 atomic_set(&page->_mapcount, -1);
586 * If network-based swap is enabled, sl*b must keep track of whether pages
587 * were allocated from pfmemalloc reserves.
589 static inline int PageSlabPfmemalloc(struct page *page)
591 VM_BUG_ON_PAGE(!PageSlab(page), page);
592 return PageActive(page);
595 static inline void SetPageSlabPfmemalloc(struct page *page)
597 VM_BUG_ON_PAGE(!PageSlab(page), page);
601 static inline void __ClearPageSlabPfmemalloc(struct page *page)
603 VM_BUG_ON_PAGE(!PageSlab(page), page);
604 __ClearPageActive(page);
607 static inline void ClearPageSlabPfmemalloc(struct page *page)
609 VM_BUG_ON_PAGE(!PageSlab(page), page);
610 ClearPageActive(page);
614 #define __PG_MLOCKED (1 << PG_mlocked)
616 #define __PG_MLOCKED 0
619 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
620 #define __PG_COMPOUND_LOCK (1 << PG_compound_lock)
622 #define __PG_COMPOUND_LOCK 0
626 * Flags checked when a page is freed. Pages being freed should not have
627 * these flags set. It they are, there is a problem.
629 #define PAGE_FLAGS_CHECK_AT_FREE \
630 (1 << PG_lru | 1 << PG_locked | \
631 1 << PG_private | 1 << PG_private_2 | \
632 1 << PG_writeback | 1 << PG_reserved | \
633 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
634 1 << PG_unevictable | __PG_MLOCKED | \
638 * Flags checked when a page is prepped for return by the page allocator.
639 * Pages being prepped should not have these flags set. It they are set,
640 * there has been a kernel bug or struct page corruption.
642 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
643 * alloc-free cycle to prevent from reusing the page.
645 #define PAGE_FLAGS_CHECK_AT_PREP \
646 (((1 << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
648 #define PAGE_FLAGS_PRIVATE \
649 (1 << PG_private | 1 << PG_private_2)
651 * page_has_private - Determine if page has private stuff
652 * @page: The page to be checked
654 * Determine if a page has private stuff, indicating that release routines
655 * should be invoked upon it.
657 static inline int page_has_private(struct page *page)
659 return !!(page->flags & PAGE_FLAGS_PRIVATE);
665 #undef PF_NO_COMPOUND
666 #endif /* !__GENERATING_BOUNDS_H */
668 #endif /* PAGE_FLAGS_H */