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 /* Page flags policies wrt compound pages */
137 #define PF_ANY(page, enforce) page
138 #define PF_HEAD(page, enforce) compound_head(page)
139 #define PF_NO_TAIL(page, enforce) ({ \
141 VM_BUG_ON_PAGE(PageTail(page), page); \
143 page = compound_head(page); \
145 #define PF_NO_COMPOUND(page, enforce) ({ \
147 VM_BUG_ON_PAGE(PageCompound(page), page); \
151 * Macros to create function definitions for page flags
153 #define TESTPAGEFLAG(uname, lname, policy) \
154 static inline int Page##uname(struct page *page) \
155 { return test_bit(PG_##lname, &policy(page, 0)->flags); }
157 #define SETPAGEFLAG(uname, lname, policy) \
158 static inline void SetPage##uname(struct page *page) \
159 { set_bit(PG_##lname, &policy(page, 1)->flags); }
161 #define CLEARPAGEFLAG(uname, lname, policy) \
162 static inline void ClearPage##uname(struct page *page) \
163 { clear_bit(PG_##lname, &policy(page, 1)->flags); }
165 #define __SETPAGEFLAG(uname, lname, policy) \
166 static inline void __SetPage##uname(struct page *page) \
167 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
169 #define __CLEARPAGEFLAG(uname, lname, policy) \
170 static inline void __ClearPage##uname(struct page *page) \
171 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
173 #define TESTSETFLAG(uname, lname, policy) \
174 static inline int TestSetPage##uname(struct page *page) \
175 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
177 #define TESTCLEARFLAG(uname, lname, policy) \
178 static inline int TestClearPage##uname(struct page *page) \
179 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
181 #define __TESTCLEARFLAG(uname, lname, policy) \
182 static inline int __TestClearPage##uname(struct page *page) \
183 { return __test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
185 #define PAGEFLAG(uname, lname, policy) \
186 TESTPAGEFLAG(uname, lname, policy) \
187 SETPAGEFLAG(uname, lname, policy) \
188 CLEARPAGEFLAG(uname, lname, policy)
190 #define __PAGEFLAG(uname, lname, policy) \
191 TESTPAGEFLAG(uname, lname, policy) \
192 __SETPAGEFLAG(uname, lname, policy) \
193 __CLEARPAGEFLAG(uname, lname, policy)
195 #define TESTSCFLAG(uname, lname, policy) \
196 TESTSETFLAG(uname, lname, policy) \
197 TESTCLEARFLAG(uname, lname, policy)
199 #define TESTPAGEFLAG_FALSE(uname) \
200 static inline int Page##uname(const struct page *page) { return 0; }
202 #define SETPAGEFLAG_NOOP(uname) \
203 static inline void SetPage##uname(struct page *page) { }
205 #define CLEARPAGEFLAG_NOOP(uname) \
206 static inline void ClearPage##uname(struct page *page) { }
208 #define __CLEARPAGEFLAG_NOOP(uname) \
209 static inline void __ClearPage##uname(struct page *page) { }
211 #define TESTSETFLAG_FALSE(uname) \
212 static inline int TestSetPage##uname(struct page *page) { return 0; }
214 #define TESTCLEARFLAG_FALSE(uname) \
215 static inline int TestClearPage##uname(struct page *page) { return 0; }
217 #define __TESTCLEARFLAG_FALSE(uname) \
218 static inline int __TestClearPage##uname(struct page *page) { return 0; }
220 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \
221 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
223 #define TESTSCFLAG_FALSE(uname) \
224 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
226 /* Forward declarations */
228 static inline int PageCompound(struct page *page);
229 static inline int PageTail(struct page *page);
230 static inline struct page *compound_head(struct page *page);
232 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
233 PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND)
234 PAGEFLAG(Referenced, referenced, PF_HEAD)
235 TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
236 __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
237 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
238 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
239 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
240 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
241 TESTCLEARFLAG(Active, active, PF_HEAD)
242 __PAGEFLAG(Slab, slab, PF_NO_TAIL)
243 __PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
244 PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
247 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND) TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
248 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND)
249 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND)
251 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
252 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
253 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
254 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
255 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
258 * Private page markings that may be used by the filesystem that owns the page
259 * for its own purposes.
260 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
262 PAGEFLAG(Private, private, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY)
263 __CLEARPAGEFLAG(Private, private, PF_ANY)
264 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
265 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
266 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
269 * Only test-and-set exist for PG_writeback. The unconditional operators are
270 * risky: they bypass page accounting.
272 TESTPAGEFLAG(Writeback, writeback, PF_NO_COMPOUND)
273 TESTSCFLAG(Writeback, writeback, PF_NO_COMPOUND)
274 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_COMPOUND)
276 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
277 PAGEFLAG(Reclaim, reclaim, PF_NO_COMPOUND)
278 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_COMPOUND)
279 PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
280 TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
282 #ifdef CONFIG_HIGHMEM
284 * Must use a macro here due to header dependency issues. page_zone() is not
285 * available at this point.
287 #define PageHighMem(__p) is_highmem(page_zone(__p))
289 PAGEFLAG_FALSE(HighMem)
293 PAGEFLAG(SwapCache, swapcache, PF_NO_COMPOUND)
295 PAGEFLAG_FALSE(SwapCache)
298 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
299 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
300 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
303 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL) __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
304 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
305 __TESTCLEARFLAG(Mlocked, mlocked, PF_NO_TAIL)
307 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
308 TESTSCFLAG_FALSE(Mlocked) __TESTCLEARFLAG_FALSE(Mlocked)
311 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
312 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
314 PAGEFLAG_FALSE(Uncached)
317 #ifdef CONFIG_MEMORY_FAILURE
318 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
319 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
320 #define __PG_HWPOISON (1UL << PG_hwpoison)
322 PAGEFLAG_FALSE(HWPoison)
323 #define __PG_HWPOISON 0
326 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
327 TESTPAGEFLAG(Young, young, PF_ANY)
328 SETPAGEFLAG(Young, young, PF_ANY)
329 TESTCLEARFLAG(Young, young, PF_ANY)
330 PAGEFLAG(Idle, idle, PF_ANY)
334 * On an anonymous page mapped into a user virtual memory area,
335 * page->mapping points to its anon_vma, not to a struct address_space;
336 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
338 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
339 * the PAGE_MAPPING_KSM bit may be set along with the PAGE_MAPPING_ANON bit;
340 * and then page->mapping points, not to an anon_vma, but to a private
341 * structure which KSM associates with that merged page. See ksm.h.
343 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is currently never used.
345 * Please note that, confusingly, "page_mapping" refers to the inode
346 * address_space which maps the page from disk; whereas "page_mapped"
347 * refers to user virtual address space into which the page is mapped.
349 #define PAGE_MAPPING_ANON 1
350 #define PAGE_MAPPING_KSM 2
351 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM)
353 static inline int PageAnon(struct page *page)
355 page = compound_head(page);
356 return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
361 * A KSM page is one of those write-protected "shared pages" or "merged pages"
362 * which KSM maps into multiple mms, wherever identical anonymous page content
363 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
364 * anon_vma, but to that page's node of the stable tree.
366 static inline int PageKsm(struct page *page)
368 page = compound_head(page);
369 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
370 (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
373 TESTPAGEFLAG_FALSE(Ksm)
376 u64 stable_page_flags(struct page *page);
378 static inline int PageUptodate(struct page *page)
381 page = compound_head(page);
382 ret = test_bit(PG_uptodate, &(page)->flags);
384 * Must ensure that the data we read out of the page is loaded
385 * _after_ we've loaded page->flags to check for PageUptodate.
386 * We can skip the barrier if the page is not uptodate, because
387 * we wouldn't be reading anything from it.
389 * See SetPageUptodate() for the other side of the story.
397 static inline void __SetPageUptodate(struct page *page)
399 VM_BUG_ON_PAGE(PageTail(page), page);
401 __set_bit(PG_uptodate, &page->flags);
404 static inline void SetPageUptodate(struct page *page)
406 VM_BUG_ON_PAGE(PageTail(page), page);
408 * Memory barrier must be issued before setting the PG_uptodate bit,
409 * so that all previous stores issued in order to bring the page
410 * uptodate are actually visible before PageUptodate becomes true.
413 set_bit(PG_uptodate, &page->flags);
416 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
418 int test_clear_page_writeback(struct page *page);
419 int __test_set_page_writeback(struct page *page, bool keep_write);
421 #define test_set_page_writeback(page) \
422 __test_set_page_writeback(page, false)
423 #define test_set_page_writeback_keepwrite(page) \
424 __test_set_page_writeback(page, true)
426 static inline void set_page_writeback(struct page *page)
428 test_set_page_writeback(page);
431 static inline void set_page_writeback_keepwrite(struct page *page)
433 test_set_page_writeback_keepwrite(page);
436 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
438 static inline int PageTail(struct page *page)
440 return READ_ONCE(page->compound_head) & 1;
443 static inline void set_compound_head(struct page *page, struct page *head)
445 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
448 static inline void clear_compound_head(struct page *page)
450 WRITE_ONCE(page->compound_head, 0);
453 static inline struct page *compound_head(struct page *page)
455 unsigned long head = READ_ONCE(page->compound_head);
457 if (unlikely(head & 1))
458 return (struct page *) (head - 1);
462 static inline int PageCompound(struct page *page)
464 return PageHead(page) || PageTail(page);
467 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
468 static inline void ClearPageCompound(struct page *page)
470 BUG_ON(!PageHead(page));
475 #define PG_head_mask ((1L << PG_head))
477 #ifdef CONFIG_HUGETLB_PAGE
478 int PageHuge(struct page *page);
479 int PageHeadHuge(struct page *page);
480 bool page_huge_active(struct page *page);
482 TESTPAGEFLAG_FALSE(Huge)
483 TESTPAGEFLAG_FALSE(HeadHuge)
485 static inline bool page_huge_active(struct page *page)
492 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
494 * PageHuge() only returns true for hugetlbfs pages, but not for
495 * normal or transparent huge pages.
497 * PageTransHuge() returns true for both transparent huge and
498 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
499 * called only in the core VM paths where hugetlbfs pages can't exist.
501 static inline int PageTransHuge(struct page *page)
503 VM_BUG_ON_PAGE(PageTail(page), page);
504 return PageHead(page);
508 * PageTransCompound returns true for both transparent huge pages
509 * and hugetlbfs pages, so it should only be called when it's known
510 * that hugetlbfs pages aren't involved.
512 static inline int PageTransCompound(struct page *page)
514 return PageCompound(page);
518 * PageTransTail returns true for both transparent huge pages
519 * and hugetlbfs pages, so it should only be called when it's known
520 * that hugetlbfs pages aren't involved.
522 static inline int PageTransTail(struct page *page)
524 return PageTail(page);
528 TESTPAGEFLAG_FALSE(TransHuge)
529 TESTPAGEFLAG_FALSE(TransCompound)
530 TESTPAGEFLAG_FALSE(TransTail)
534 * PageBuddy() indicate that the page is free and in the buddy system
535 * (see mm/page_alloc.c).
537 * PAGE_BUDDY_MAPCOUNT_VALUE must be <= -2 but better not too close to
538 * -2 so that an underflow of the page_mapcount() won't be mistaken
539 * for a genuine PAGE_BUDDY_MAPCOUNT_VALUE. -128 can be created very
540 * efficiently by most CPU architectures.
542 #define PAGE_BUDDY_MAPCOUNT_VALUE (-128)
544 static inline int PageBuddy(struct page *page)
546 return atomic_read(&page->_mapcount) == PAGE_BUDDY_MAPCOUNT_VALUE;
549 static inline void __SetPageBuddy(struct page *page)
551 VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
552 atomic_set(&page->_mapcount, PAGE_BUDDY_MAPCOUNT_VALUE);
555 static inline void __ClearPageBuddy(struct page *page)
557 VM_BUG_ON_PAGE(!PageBuddy(page), page);
558 atomic_set(&page->_mapcount, -1);
561 #define PAGE_BALLOON_MAPCOUNT_VALUE (-256)
563 static inline int PageBalloon(struct page *page)
565 return atomic_read(&page->_mapcount) == PAGE_BALLOON_MAPCOUNT_VALUE;
568 static inline void __SetPageBalloon(struct page *page)
570 VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
571 atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE);
574 static inline void __ClearPageBalloon(struct page *page)
576 VM_BUG_ON_PAGE(!PageBalloon(page), page);
577 atomic_set(&page->_mapcount, -1);
581 * If network-based swap is enabled, sl*b must keep track of whether pages
582 * were allocated from pfmemalloc reserves.
584 static inline int PageSlabPfmemalloc(struct page *page)
586 VM_BUG_ON_PAGE(!PageSlab(page), page);
587 return PageActive(page);
590 static inline void SetPageSlabPfmemalloc(struct page *page)
592 VM_BUG_ON_PAGE(!PageSlab(page), page);
596 static inline void __ClearPageSlabPfmemalloc(struct page *page)
598 VM_BUG_ON_PAGE(!PageSlab(page), page);
599 __ClearPageActive(page);
602 static inline void ClearPageSlabPfmemalloc(struct page *page)
604 VM_BUG_ON_PAGE(!PageSlab(page), page);
605 ClearPageActive(page);
609 #define __PG_MLOCKED (1 << PG_mlocked)
611 #define __PG_MLOCKED 0
614 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
615 #define __PG_COMPOUND_LOCK (1 << PG_compound_lock)
617 #define __PG_COMPOUND_LOCK 0
621 * Flags checked when a page is freed. Pages being freed should not have
622 * these flags set. It they are, there is a problem.
624 #define PAGE_FLAGS_CHECK_AT_FREE \
625 (1 << PG_lru | 1 << PG_locked | \
626 1 << PG_private | 1 << PG_private_2 | \
627 1 << PG_writeback | 1 << PG_reserved | \
628 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \
629 1 << PG_unevictable | __PG_MLOCKED | \
633 * Flags checked when a page is prepped for return by the page allocator.
634 * Pages being prepped should not have these flags set. It they are set,
635 * there has been a kernel bug or struct page corruption.
637 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
638 * alloc-free cycle to prevent from reusing the page.
640 #define PAGE_FLAGS_CHECK_AT_PREP \
641 (((1 << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
643 #define PAGE_FLAGS_PRIVATE \
644 (1 << PG_private | 1 << PG_private_2)
646 * page_has_private - Determine if page has private stuff
647 * @page: The page to be checked
649 * Determine if a page has private stuff, indicating that release routines
650 * should be invoked upon it.
652 static inline int page_has_private(struct page *page)
654 return !!(page->flags & PAGE_FLAGS_PRIVATE);
660 #undef PF_NO_COMPOUND
661 #endif /* !__GENERATING_BOUNDS_H */
663 #endif /* PAGE_FLAGS_H */