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
137 * Macros to create function definitions for page flags
139 #define TESTPAGEFLAG(uname, lname) \
140 static inline int Page##uname(const struct page *page) \
141 { return test_bit(PG_##lname, &page->flags); }
143 #define SETPAGEFLAG(uname, lname) \
144 static inline void SetPage##uname(struct page *page) \
145 { set_bit(PG_##lname, &page->flags); }
147 #define CLEARPAGEFLAG(uname, lname) \
148 static inline void ClearPage##uname(struct page *page) \
149 { clear_bit(PG_##lname, &page->flags); }
151 #define __SETPAGEFLAG(uname, lname) \
152 static inline void __SetPage##uname(struct page *page) \
153 { __set_bit(PG_##lname, &page->flags); }
155 #define __CLEARPAGEFLAG(uname, lname) \
156 static inline void __ClearPage##uname(struct page *page) \
157 { __clear_bit(PG_##lname, &page->flags); }
159 #define TESTSETFLAG(uname, lname) \
160 static inline int TestSetPage##uname(struct page *page) \
161 { return test_and_set_bit(PG_##lname, &page->flags); }
163 #define TESTCLEARFLAG(uname, lname) \
164 static inline int TestClearPage##uname(struct page *page) \
165 { return test_and_clear_bit(PG_##lname, &page->flags); }
167 #define __TESTCLEARFLAG(uname, lname) \
168 static inline int __TestClearPage##uname(struct page *page) \
169 { return __test_and_clear_bit(PG_##lname, &page->flags); }
171 #define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
172 SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname)
174 #define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
175 __SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname)
177 #define TESTSCFLAG(uname, lname) \
178 TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)
180 #define TESTPAGEFLAG_FALSE(uname) \
181 static inline int Page##uname(const struct page *page) { return 0; }
183 #define SETPAGEFLAG_NOOP(uname) \
184 static inline void SetPage##uname(struct page *page) { }
186 #define CLEARPAGEFLAG_NOOP(uname) \
187 static inline void ClearPage##uname(struct page *page) { }
189 #define __CLEARPAGEFLAG_NOOP(uname) \
190 static inline void __ClearPage##uname(struct page *page) { }
192 #define TESTSETFLAG_FALSE(uname) \
193 static inline int TestSetPage##uname(struct page *page) { return 0; }
195 #define TESTCLEARFLAG_FALSE(uname) \
196 static inline int TestClearPage##uname(struct page *page) { return 0; }
198 #define __TESTCLEARFLAG_FALSE(uname) \
199 static inline int __TestClearPage##uname(struct page *page) { return 0; }
201 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \
202 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
204 #define TESTSCFLAG_FALSE(uname) \
205 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
207 struct page; /* forward declaration */
209 TESTPAGEFLAG(Locked, locked)
210 PAGEFLAG(Error, error) TESTCLEARFLAG(Error, error)
211 PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
212 __SETPAGEFLAG(Referenced, referenced)
213 PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty)
214 PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru)
215 PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active)
216 TESTCLEARFLAG(Active, active)
217 __PAGEFLAG(Slab, slab)
218 PAGEFLAG(Checked, checked) /* Used by some filesystems */
219 PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen */
220 PAGEFLAG(SavePinned, savepinned); /* Xen */
221 PAGEFLAG(Foreign, foreign); /* Xen */
222 PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
223 PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked)
224 __SETPAGEFLAG(SwapBacked, swapbacked)
226 __PAGEFLAG(SlobFree, slob_free)
229 * Private page markings that may be used by the filesystem that owns the page
230 * for its own purposes.
231 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
233 PAGEFLAG(Private, private) __SETPAGEFLAG(Private, private)
234 __CLEARPAGEFLAG(Private, private)
235 PAGEFLAG(Private2, private_2) TESTSCFLAG(Private2, private_2)
236 PAGEFLAG(OwnerPriv1, owner_priv_1) TESTCLEARFLAG(OwnerPriv1, owner_priv_1)
239 * Only test-and-set exist for PG_writeback. The unconditional operators are
240 * risky: they bypass page accounting.
242 TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback)
243 PAGEFLAG(MappedToDisk, mappedtodisk)
245 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
246 PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim)
247 PAGEFLAG(Readahead, reclaim) TESTCLEARFLAG(Readahead, reclaim)
249 #ifdef CONFIG_HIGHMEM
251 * Must use a macro here due to header dependency issues. page_zone() is not
252 * available at this point.
254 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
256 PAGEFLAG_FALSE(HighMem)
260 PAGEFLAG(SwapCache, swapcache)
262 PAGEFLAG_FALSE(SwapCache)
265 PAGEFLAG(Unevictable, unevictable) __CLEARPAGEFLAG(Unevictable, unevictable)
266 TESTCLEARFLAG(Unevictable, unevictable)
269 PAGEFLAG(Mlocked, mlocked) __CLEARPAGEFLAG(Mlocked, mlocked)
270 TESTSCFLAG(Mlocked, mlocked) __TESTCLEARFLAG(Mlocked, mlocked)
272 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
273 TESTSCFLAG_FALSE(Mlocked) __TESTCLEARFLAG_FALSE(Mlocked)
276 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
277 PAGEFLAG(Uncached, uncached)
279 PAGEFLAG_FALSE(Uncached)
282 #ifdef CONFIG_MEMORY_FAILURE
283 PAGEFLAG(HWPoison, hwpoison)
284 TESTSCFLAG(HWPoison, hwpoison)
285 #define __PG_HWPOISON (1UL << PG_hwpoison)
287 PAGEFLAG_FALSE(HWPoison)
288 #define __PG_HWPOISON 0
291 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
292 TESTPAGEFLAG(Young, young)
293 SETPAGEFLAG(Young, young)
294 TESTCLEARFLAG(Young, young)
299 * On an anonymous page mapped into a user virtual memory area,
300 * page->mapping points to its anon_vma, not to a struct address_space;
301 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
303 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
304 * the PAGE_MAPPING_KSM bit may be set along with the PAGE_MAPPING_ANON bit;
305 * and then page->mapping points, not to an anon_vma, but to a private
306 * structure which KSM associates with that merged page. See ksm.h.
308 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is currently never used.
310 * Please note that, confusingly, "page_mapping" refers to the inode
311 * address_space which maps the page from disk; whereas "page_mapped"
312 * refers to user virtual address space into which the page is mapped.
314 #define PAGE_MAPPING_ANON 1
315 #define PAGE_MAPPING_KSM 2
316 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM)
318 static inline int PageAnon(struct page *page)
320 return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
325 * A KSM page is one of those write-protected "shared pages" or "merged pages"
326 * which KSM maps into multiple mms, wherever identical anonymous page content
327 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
328 * anon_vma, but to that page's node of the stable tree.
330 static inline int PageKsm(struct page *page)
332 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
333 (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
336 TESTPAGEFLAG_FALSE(Ksm)
339 u64 stable_page_flags(struct page *page);
341 static inline int PageUptodate(struct page *page)
343 int ret = test_bit(PG_uptodate, &(page)->flags);
346 * Must ensure that the data we read out of the page is loaded
347 * _after_ we've loaded page->flags to check for PageUptodate.
348 * We can skip the barrier if the page is not uptodate, because
349 * we wouldn't be reading anything from it.
351 * See SetPageUptodate() for the other side of the story.
359 static inline void __SetPageUptodate(struct page *page)
362 __set_bit(PG_uptodate, &(page)->flags);
365 static inline void SetPageUptodate(struct page *page)
368 * Memory barrier must be issued before setting the PG_uptodate bit,
369 * so that all previous stores issued in order to bring the page
370 * uptodate are actually visible before PageUptodate becomes true.
373 set_bit(PG_uptodate, &(page)->flags);
376 CLEARPAGEFLAG(Uptodate, uptodate)
378 int test_clear_page_writeback(struct page *page);
379 int __test_set_page_writeback(struct page *page, bool keep_write);
381 #define test_set_page_writeback(page) \
382 __test_set_page_writeback(page, false)
383 #define test_set_page_writeback_keepwrite(page) \
384 __test_set_page_writeback(page, true)
386 static inline void set_page_writeback(struct page *page)
388 test_set_page_writeback(page);
391 static inline void set_page_writeback_keepwrite(struct page *page)
393 test_set_page_writeback_keepwrite(page);
396 __PAGEFLAG(Head, head) CLEARPAGEFLAG(Head, head)
398 static inline int PageTail(struct page *page)
400 return READ_ONCE(page->compound_head) & 1;
403 static inline void set_compound_head(struct page *page, struct page *head)
405 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
408 static inline void clear_compound_head(struct page *page)
410 WRITE_ONCE(page->compound_head, 0);
413 static inline struct page *compound_head(struct page *page)
415 unsigned long head = READ_ONCE(page->compound_head);
417 if (unlikely(head & 1))
418 return (struct page *) (head - 1);
422 static inline int PageCompound(struct page *page)
424 return PageHead(page) || PageTail(page);
427 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
428 static inline void ClearPageCompound(struct page *page)
430 BUG_ON(!PageHead(page));
435 #define PG_head_mask ((1L << PG_head))
437 #ifdef CONFIG_HUGETLB_PAGE
438 int PageHuge(struct page *page);
439 int PageHeadHuge(struct page *page);
440 bool page_huge_active(struct page *page);
442 TESTPAGEFLAG_FALSE(Huge)
443 TESTPAGEFLAG_FALSE(HeadHuge)
445 static inline bool page_huge_active(struct page *page)
452 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
454 * PageHuge() only returns true for hugetlbfs pages, but not for
455 * normal or transparent huge pages.
457 * PageTransHuge() returns true for both transparent huge and
458 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
459 * called only in the core VM paths where hugetlbfs pages can't exist.
461 static inline int PageTransHuge(struct page *page)
463 VM_BUG_ON_PAGE(PageTail(page), page);
464 return PageHead(page);
468 * PageTransCompound returns true for both transparent huge pages
469 * and hugetlbfs pages, so it should only be called when it's known
470 * that hugetlbfs pages aren't involved.
472 static inline int PageTransCompound(struct page *page)
474 return PageCompound(page);
478 * PageTransTail returns true for both transparent huge pages
479 * and hugetlbfs pages, so it should only be called when it's known
480 * that hugetlbfs pages aren't involved.
482 static inline int PageTransTail(struct page *page)
484 return PageTail(page);
489 static inline int PageTransHuge(struct page *page)
494 static inline int PageTransCompound(struct page *page)
499 static inline int PageTransTail(struct page *page)
506 * PageBuddy() indicate that the page is free and in the buddy system
507 * (see mm/page_alloc.c).
509 * PAGE_BUDDY_MAPCOUNT_VALUE must be <= -2 but better not too close to
510 * -2 so that an underflow of the page_mapcount() won't be mistaken
511 * for a genuine PAGE_BUDDY_MAPCOUNT_VALUE. -128 can be created very
512 * efficiently by most CPU architectures.
514 #define PAGE_BUDDY_MAPCOUNT_VALUE (-128)
516 static inline int PageBuddy(struct page *page)
518 return atomic_read(&page->_mapcount) == PAGE_BUDDY_MAPCOUNT_VALUE;
521 static inline void __SetPageBuddy(struct page *page)
523 VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
524 atomic_set(&page->_mapcount, PAGE_BUDDY_MAPCOUNT_VALUE);
527 static inline void __ClearPageBuddy(struct page *page)
529 VM_BUG_ON_PAGE(!PageBuddy(page), page);
530 atomic_set(&page->_mapcount, -1);
533 #define PAGE_BALLOON_MAPCOUNT_VALUE (-256)
535 static inline int PageBalloon(struct page *page)
537 return atomic_read(&page->_mapcount) == PAGE_BALLOON_MAPCOUNT_VALUE;
540 static inline void __SetPageBalloon(struct page *page)
542 VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
543 atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE);
546 static inline void __ClearPageBalloon(struct page *page)
548 VM_BUG_ON_PAGE(!PageBalloon(page), page);
549 atomic_set(&page->_mapcount, -1);
553 * If network-based swap is enabled, sl*b must keep track of whether pages
554 * were allocated from pfmemalloc reserves.
556 static inline int PageSlabPfmemalloc(struct page *page)
558 VM_BUG_ON_PAGE(!PageSlab(page), page);
559 return PageActive(page);
562 static inline void SetPageSlabPfmemalloc(struct page *page)
564 VM_BUG_ON_PAGE(!PageSlab(page), page);
568 static inline void __ClearPageSlabPfmemalloc(struct page *page)
570 VM_BUG_ON_PAGE(!PageSlab(page), page);
571 __ClearPageActive(page);
574 static inline void ClearPageSlabPfmemalloc(struct page *page)
576 VM_BUG_ON_PAGE(!PageSlab(page), page);
577 ClearPageActive(page);
581 #define __PG_MLOCKED (1 << PG_mlocked)
583 #define __PG_MLOCKED 0
586 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
587 #define __PG_COMPOUND_LOCK (1 << PG_compound_lock)
589 #define __PG_COMPOUND_LOCK 0
593 * Flags checked when a page is freed. Pages being freed should not have
594 * these flags set. It they are, there is a problem.
596 #define PAGE_FLAGS_CHECK_AT_FREE \
597 (1 << PG_lru | 1 << PG_locked | \
598 1 << PG_private | 1 << PG_private_2 | \
599 1 << PG_writeback | 1 << PG_reserved | \
600 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
601 1 << PG_unevictable | __PG_MLOCKED | \
605 * Flags checked when a page is prepped for return by the page allocator.
606 * Pages being prepped should not have these flags set. It they are set,
607 * there has been a kernel bug or struct page corruption.
609 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
610 * alloc-free cycle to prevent from reusing the page.
612 #define PAGE_FLAGS_CHECK_AT_PREP \
613 (((1 << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
615 #define PAGE_FLAGS_PRIVATE \
616 (1 << PG_private | 1 << PG_private_2)
618 * page_has_private - Determine if page has private stuff
619 * @page: The page to be checked
621 * Determine if a page has private stuff, indicating that release routines
622 * should be invoked upon it.
624 static inline int page_has_private(struct page *page)
626 return !!(page->flags & PAGE_FLAGS_PRIVATE);
629 #endif /* !__GENERATING_BOUNDS_H */
631 #endif /* PAGE_FLAGS_H */