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. The "struct page" of such a page
21 * should in general not be touched (e.g. set dirty) except by its owner.
22 * Pages marked as PG_reserved include:
23 * - Pages part of the kernel image (including vDSO) and similar (e.g. BIOS,
25 * - Pages reserved or allocated early during boot (before the page allocator
26 * was initialized). This includes (depending on the architecture) the
27 * initial vmemmap, initial page tables, crashkernel, elfcorehdr, and much
28 * much more. Once (if ever) freed, PG_reserved is cleared and they will
29 * be given to the page allocator.
30 * - Pages falling into physical memory gaps - not IORESOURCE_SYSRAM. Trying
31 * to read/write these pages might end badly. Don't touch!
33 * - Pages not added to the page allocator when onlining a section because
34 * they were excluded via the online_page_callback() or because they are
36 * - Pages allocated in the context of kexec/kdump (loaded kernel image,
37 * control pages, vmcoreinfo)
38 * - MMIO/DMA pages. Some architectures don't allow to ioremap pages that are
39 * not marked PG_reserved (as they might be in use by somebody else who does
40 * not respect the caching strategy).
41 * - Pages part of an offline section (struct pages of offline sections should
42 * not be trusted as they will be initialized when first onlined).
44 * - Pages holding CPU notes for POWER Firmware Assisted Dump
45 * - Device memory (e.g. PMEM, DAX, HMM)
46 * Some PG_reserved pages will be excluded from the hibernation image.
47 * PG_reserved does in general not hinder anybody from dumping or swapping
48 * and is no longer required for remap_pfn_range(). ioremap might require it.
49 * Consequently, PG_reserved for a page mapped into user space can indicate
50 * the zero page, the vDSO, MMIO pages or device memory.
52 * The PG_private bitflag is set on pagecache pages if they contain filesystem
53 * specific data (which is normally at page->private). It can be used by
54 * private allocations for its own usage.
56 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O
57 * and cleared when writeback _starts_ or when read _completes_. PG_writeback
58 * is set before writeback starts and cleared when it finishes.
60 * PG_locked also pins a page in pagecache, and blocks truncation of the file
63 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
66 * PG_uptodate tells whether the page's contents is valid. When a read
67 * completes, the page becomes uptodate, unless a disk I/O error happened.
69 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
70 * file-backed pagecache (see mm/vmscan.c).
72 * PG_error is set to indicate that an I/O error occurred on this page.
74 * PG_arch_1 is an architecture specific page state bit. The generic code
75 * guarantees that this bit is cleared for a page when it first is entered into
78 * PG_hwpoison indicates that a page got corrupted in hardware and contains
79 * data with incorrect ECC bits that triggered a machine check. Accessing is
80 * not safe since it may cause another machine check. Don't touch!
84 * Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
85 * locked- and dirty-page accounting.
87 * The page flags field is split into two parts, the main flags area
88 * which extends from the low bits upwards, and the fields area which
89 * extends from the high bits downwards.
91 * | FIELD | ... | FLAGS |
95 * The fields area is reserved for fields mapping zone, node (for NUMA) and
96 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like
97 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
100 PG_locked, /* Page is locked. Don't touch. */
107 PG_waiters, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
110 PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
113 PG_private, /* If pagecache, has fs-private data */
114 PG_private_2, /* If pagecache, has fs aux data */
115 PG_writeback, /* Page is under writeback */
116 PG_head, /* A head page */
117 PG_mappedtodisk, /* Has blocks allocated on-disk */
118 PG_reclaim, /* To be reclaimed asap */
119 PG_swapbacked, /* Page is backed by RAM/swap */
120 PG_unevictable, /* Page is "unevictable" */
122 PG_mlocked, /* Page is vma mlocked */
124 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
125 PG_uncached, /* Page has been mapped as uncached */
127 #ifdef CONFIG_MEMORY_FAILURE
128 PG_hwpoison, /* hardware poisoned page. Don't touch */
130 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
137 PG_checked = PG_owner_priv_1,
140 PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */
142 /* Two page bits are conscripted by FS-Cache to maintain local caching
143 * state. These bits are set on pages belonging to the netfs's inodes
144 * when those inodes are being locally cached.
146 PG_fscache = PG_private_2, /* page backed by cache */
149 /* Pinned in Xen as a read-only pagetable page. */
150 PG_pinned = PG_owner_priv_1,
151 /* Pinned as part of domain save (see xen_mm_pin_all()). */
152 PG_savepinned = PG_dirty,
153 /* Has a grant mapping of another (foreign) domain's page. */
154 PG_foreign = PG_owner_priv_1,
157 PG_slob_free = PG_private,
159 /* Compound pages. Stored in first tail page's flags */
160 PG_double_map = PG_private_2,
162 /* non-lru isolated movable page */
163 PG_isolated = PG_reclaim,
166 #ifndef __GENERATING_BOUNDS_H
168 struct page; /* forward declaration */
170 static inline struct page *compound_head(struct page *page)
172 unsigned long head = READ_ONCE(page->compound_head);
174 if (unlikely(head & 1))
175 return (struct page *) (head - 1);
179 static __always_inline int PageTail(struct page *page)
181 return READ_ONCE(page->compound_head) & 1;
184 static __always_inline int PageCompound(struct page *page)
186 return test_bit(PG_head, &page->flags) || PageTail(page);
189 #define PAGE_POISON_PATTERN -1l
190 static inline int PagePoisoned(const struct page *page)
192 return page->flags == PAGE_POISON_PATTERN;
195 #ifdef CONFIG_DEBUG_VM
196 void page_init_poison(struct page *page, size_t size);
198 static inline void page_init_poison(struct page *page, size_t size)
204 * Page flags policies wrt compound pages
207 * check if this struct page poisoned/uninitialized
210 * the page flag is relevant for small, head and tail pages.
213 * for compound page all operations related to the page flag applied to
217 * for compound page, callers only ever operate on the head page.
220 * modifications of the page flag must be done on small or head pages,
221 * checks can be done on tail pages too.
224 * the page flag is not relevant for compound pages.
226 #define PF_POISONED_CHECK(page) ({ \
227 VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \
229 #define PF_ANY(page, enforce) PF_POISONED_CHECK(page)
230 #define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page))
231 #define PF_ONLY_HEAD(page, enforce) ({ \
232 VM_BUG_ON_PGFLAGS(PageTail(page), page); \
233 PF_POISONED_CHECK(page); })
234 #define PF_NO_TAIL(page, enforce) ({ \
235 VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
236 PF_POISONED_CHECK(compound_head(page)); })
237 #define PF_NO_COMPOUND(page, enforce) ({ \
238 VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
239 PF_POISONED_CHECK(page); })
242 * Macros to create function definitions for page flags
244 #define TESTPAGEFLAG(uname, lname, policy) \
245 static __always_inline int Page##uname(struct page *page) \
246 { return test_bit(PG_##lname, &policy(page, 0)->flags); }
248 #define SETPAGEFLAG(uname, lname, policy) \
249 static __always_inline void SetPage##uname(struct page *page) \
250 { set_bit(PG_##lname, &policy(page, 1)->flags); }
252 #define CLEARPAGEFLAG(uname, lname, policy) \
253 static __always_inline void ClearPage##uname(struct page *page) \
254 { clear_bit(PG_##lname, &policy(page, 1)->flags); }
256 #define __SETPAGEFLAG(uname, lname, policy) \
257 static __always_inline void __SetPage##uname(struct page *page) \
258 { __set_bit(PG_##lname, &policy(page, 1)->flags); }
260 #define __CLEARPAGEFLAG(uname, lname, policy) \
261 static __always_inline void __ClearPage##uname(struct page *page) \
262 { __clear_bit(PG_##lname, &policy(page, 1)->flags); }
264 #define TESTSETFLAG(uname, lname, policy) \
265 static __always_inline int TestSetPage##uname(struct page *page) \
266 { return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
268 #define TESTCLEARFLAG(uname, lname, policy) \
269 static __always_inline int TestClearPage##uname(struct page *page) \
270 { return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
272 #define PAGEFLAG(uname, lname, policy) \
273 TESTPAGEFLAG(uname, lname, policy) \
274 SETPAGEFLAG(uname, lname, policy) \
275 CLEARPAGEFLAG(uname, lname, policy)
277 #define __PAGEFLAG(uname, lname, policy) \
278 TESTPAGEFLAG(uname, lname, policy) \
279 __SETPAGEFLAG(uname, lname, policy) \
280 __CLEARPAGEFLAG(uname, lname, policy)
282 #define TESTSCFLAG(uname, lname, policy) \
283 TESTSETFLAG(uname, lname, policy) \
284 TESTCLEARFLAG(uname, lname, policy)
286 #define TESTPAGEFLAG_FALSE(uname) \
287 static inline int Page##uname(const struct page *page) { return 0; }
289 #define SETPAGEFLAG_NOOP(uname) \
290 static inline void SetPage##uname(struct page *page) { }
292 #define CLEARPAGEFLAG_NOOP(uname) \
293 static inline void ClearPage##uname(struct page *page) { }
295 #define __CLEARPAGEFLAG_NOOP(uname) \
296 static inline void __ClearPage##uname(struct page *page) { }
298 #define TESTSETFLAG_FALSE(uname) \
299 static inline int TestSetPage##uname(struct page *page) { return 0; }
301 #define TESTCLEARFLAG_FALSE(uname) \
302 static inline int TestClearPage##uname(struct page *page) { return 0; }
304 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \
305 SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)
307 #define TESTSCFLAG_FALSE(uname) \
308 TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
310 __PAGEFLAG(Locked, locked, PF_NO_TAIL)
311 PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
312 PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND)
313 PAGEFLAG(Referenced, referenced, PF_HEAD)
314 TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
315 __SETPAGEFLAG(Referenced, referenced, PF_HEAD)
316 PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
317 __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
318 PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
319 PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
320 TESTCLEARFLAG(Active, active, PF_HEAD)
321 PAGEFLAG(Workingset, workingset, PF_HEAD)
322 TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
323 __PAGEFLAG(Slab, slab, PF_NO_TAIL)
324 __PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
325 PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
328 PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
329 TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
330 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
331 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
333 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
334 __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
335 __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
336 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
337 __CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
338 __SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
341 * Private page markings that may be used by the filesystem that owns the page
342 * for its own purposes.
343 * - PG_private and PG_private_2 cause releasepage() and co to be invoked
345 PAGEFLAG(Private, private, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY)
346 __CLEARPAGEFLAG(Private, private, PF_ANY)
347 PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
348 PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
349 TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
352 * Only test-and-set exist for PG_writeback. The unconditional operators are
353 * risky: they bypass page accounting.
355 TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL)
356 TESTSCFLAG(Writeback, writeback, PF_NO_TAIL)
357 PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
359 /* PG_readahead is only used for reads; PG_reclaim is only for writes */
360 PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
361 TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL)
362 PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
363 TESTCLEARFLAG(Readahead, reclaim, PF_NO_COMPOUND)
365 #ifdef CONFIG_HIGHMEM
367 * Must use a macro here due to header dependency issues. page_zone() is not
368 * available at this point.
370 #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
372 PAGEFLAG_FALSE(HighMem)
376 static __always_inline int PageSwapCache(struct page *page)
378 #ifdef CONFIG_THP_SWAP
379 page = compound_head(page);
381 return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags);
384 SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
385 CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
387 PAGEFLAG_FALSE(SwapCache)
390 PAGEFLAG(Unevictable, unevictable, PF_HEAD)
391 __CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
392 TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
395 PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
396 __CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
397 TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
399 PAGEFLAG_FALSE(Mlocked) __CLEARPAGEFLAG_NOOP(Mlocked)
400 TESTSCFLAG_FALSE(Mlocked)
403 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
404 PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
406 PAGEFLAG_FALSE(Uncached)
409 #ifdef CONFIG_MEMORY_FAILURE
410 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
411 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
412 #define __PG_HWPOISON (1UL << PG_hwpoison)
413 extern bool set_hwpoison_free_buddy_page(struct page *page);
415 PAGEFLAG_FALSE(HWPoison)
416 static inline bool set_hwpoison_free_buddy_page(struct page *page)
420 #define __PG_HWPOISON 0
423 #if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
424 TESTPAGEFLAG(Young, young, PF_ANY)
425 SETPAGEFLAG(Young, young, PF_ANY)
426 TESTCLEARFLAG(Young, young, PF_ANY)
427 PAGEFLAG(Idle, idle, PF_ANY)
431 * On an anonymous page mapped into a user virtual memory area,
432 * page->mapping points to its anon_vma, not to a struct address_space;
433 * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h.
435 * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled,
436 * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON
437 * bit; and then page->mapping points, not to an anon_vma, but to a private
438 * structure which KSM associates with that merged page. See ksm.h.
440 * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable
441 * page and then page->mapping points a struct address_space.
443 * Please note that, confusingly, "page_mapping" refers to the inode
444 * address_space which maps the page from disk; whereas "page_mapped"
445 * refers to user virtual address space into which the page is mapped.
447 #define PAGE_MAPPING_ANON 0x1
448 #define PAGE_MAPPING_MOVABLE 0x2
449 #define PAGE_MAPPING_KSM (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
450 #define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON | PAGE_MAPPING_MOVABLE)
452 static __always_inline int PageMappingFlags(struct page *page)
454 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
457 static __always_inline int PageAnon(struct page *page)
459 page = compound_head(page);
460 return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
463 static __always_inline int __PageMovable(struct page *page)
465 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
466 PAGE_MAPPING_MOVABLE;
471 * A KSM page is one of those write-protected "shared pages" or "merged pages"
472 * which KSM maps into multiple mms, wherever identical anonymous page content
473 * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any
474 * anon_vma, but to that page's node of the stable tree.
476 static __always_inline int PageKsm(struct page *page)
478 page = compound_head(page);
479 return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
483 TESTPAGEFLAG_FALSE(Ksm)
486 u64 stable_page_flags(struct page *page);
488 static inline int PageUptodate(struct page *page)
491 page = compound_head(page);
492 ret = test_bit(PG_uptodate, &(page)->flags);
494 * Must ensure that the data we read out of the page is loaded
495 * _after_ we've loaded page->flags to check for PageUptodate.
496 * We can skip the barrier if the page is not uptodate, because
497 * we wouldn't be reading anything from it.
499 * See SetPageUptodate() for the other side of the story.
507 static __always_inline void __SetPageUptodate(struct page *page)
509 VM_BUG_ON_PAGE(PageTail(page), page);
511 __set_bit(PG_uptodate, &page->flags);
514 static __always_inline void SetPageUptodate(struct page *page)
516 VM_BUG_ON_PAGE(PageTail(page), page);
518 * Memory barrier must be issued before setting the PG_uptodate bit,
519 * so that all previous stores issued in order to bring the page
520 * uptodate are actually visible before PageUptodate becomes true.
523 set_bit(PG_uptodate, &page->flags);
526 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
528 int test_clear_page_writeback(struct page *page);
529 int __test_set_page_writeback(struct page *page, bool keep_write);
531 #define test_set_page_writeback(page) \
532 __test_set_page_writeback(page, false)
533 #define test_set_page_writeback_keepwrite(page) \
534 __test_set_page_writeback(page, true)
536 static inline void set_page_writeback(struct page *page)
538 test_set_page_writeback(page);
541 static inline void set_page_writeback_keepwrite(struct page *page)
543 test_set_page_writeback_keepwrite(page);
546 __PAGEFLAG(Head, head, PF_ANY) CLEARPAGEFLAG(Head, head, PF_ANY)
548 static __always_inline void set_compound_head(struct page *page, struct page *head)
550 WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
553 static __always_inline void clear_compound_head(struct page *page)
555 WRITE_ONCE(page->compound_head, 0);
558 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
559 static inline void ClearPageCompound(struct page *page)
561 BUG_ON(!PageHead(page));
566 #define PG_head_mask ((1UL << PG_head))
568 #ifdef CONFIG_HUGETLB_PAGE
569 int PageHuge(struct page *page);
570 int PageHeadHuge(struct page *page);
571 bool page_huge_active(struct page *page);
573 TESTPAGEFLAG_FALSE(Huge)
574 TESTPAGEFLAG_FALSE(HeadHuge)
576 static inline bool page_huge_active(struct page *page)
583 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
585 * PageHuge() only returns true for hugetlbfs pages, but not for
586 * normal or transparent huge pages.
588 * PageTransHuge() returns true for both transparent huge and
589 * hugetlbfs pages, but not normal pages. PageTransHuge() can only be
590 * called only in the core VM paths where hugetlbfs pages can't exist.
592 static inline int PageTransHuge(struct page *page)
594 VM_BUG_ON_PAGE(PageTail(page), page);
595 return PageHead(page);
599 * PageTransCompound returns true for both transparent huge pages
600 * and hugetlbfs pages, so it should only be called when it's known
601 * that hugetlbfs pages aren't involved.
603 static inline int PageTransCompound(struct page *page)
605 return PageCompound(page);
609 * PageTransCompoundMap is the same as PageTransCompound, but it also
610 * guarantees the primary MMU has the entire compound page mapped
611 * through pmd_trans_huge, which in turn guarantees the secondary MMUs
612 * can also map the entire compound page. This allows the secondary
613 * MMUs to call get_user_pages() only once for each compound page and
614 * to immediately map the entire compound page with a single secondary
615 * MMU fault. If there will be a pmd split later, the secondary MMUs
616 * will get an update through the MMU notifier invalidation through
619 * Unlike PageTransCompound, this is safe to be called only while
620 * split_huge_pmd() cannot run from under us, like if protected by the
621 * MMU notifier, otherwise it may result in page->_mapcount < 0 false
624 static inline int PageTransCompoundMap(struct page *page)
626 return PageTransCompound(page) && atomic_read(&page->_mapcount) < 0;
630 * PageTransTail returns true for both transparent huge pages
631 * and hugetlbfs pages, so it should only be called when it's known
632 * that hugetlbfs pages aren't involved.
634 static inline int PageTransTail(struct page *page)
636 return PageTail(page);
640 * PageDoubleMap indicates that the compound page is mapped with PTEs as well
643 * This is required for optimization of rmap operations for THP: we can postpone
644 * per small page mapcount accounting (and its overhead from atomic operations)
645 * until the first PMD split.
647 * For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
648 * by one. This reference will go away with last compound_mapcount.
650 * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
652 static inline int PageDoubleMap(struct page *page)
654 return PageHead(page) && test_bit(PG_double_map, &page[1].flags);
657 static inline void SetPageDoubleMap(struct page *page)
659 VM_BUG_ON_PAGE(!PageHead(page), page);
660 set_bit(PG_double_map, &page[1].flags);
663 static inline void ClearPageDoubleMap(struct page *page)
665 VM_BUG_ON_PAGE(!PageHead(page), page);
666 clear_bit(PG_double_map, &page[1].flags);
668 static inline int TestSetPageDoubleMap(struct page *page)
670 VM_BUG_ON_PAGE(!PageHead(page), page);
671 return test_and_set_bit(PG_double_map, &page[1].flags);
674 static inline int TestClearPageDoubleMap(struct page *page)
676 VM_BUG_ON_PAGE(!PageHead(page), page);
677 return test_and_clear_bit(PG_double_map, &page[1].flags);
681 TESTPAGEFLAG_FALSE(TransHuge)
682 TESTPAGEFLAG_FALSE(TransCompound)
683 TESTPAGEFLAG_FALSE(TransCompoundMap)
684 TESTPAGEFLAG_FALSE(TransTail)
685 PAGEFLAG_FALSE(DoubleMap)
686 TESTSETFLAG_FALSE(DoubleMap)
687 TESTCLEARFLAG_FALSE(DoubleMap)
691 * For pages that are never mapped to userspace (and aren't PageSlab),
692 * page_type may be used. Because it is initialised to -1, we invert the
693 * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
694 * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
695 * low bits so that an underflow or overflow of page_mapcount() won't be
696 * mistaken for a page type value.
699 #define PAGE_TYPE_BASE 0xf0000000
700 /* Reserve 0x0000007f to catch underflows of page_mapcount */
701 #define PAGE_MAPCOUNT_RESERVE -128
702 #define PG_buddy 0x00000080
703 #define PG_offline 0x00000100
704 #define PG_kmemcg 0x00000200
705 #define PG_table 0x00000400
706 #define PG_guard 0x00000800
708 #define PageType(page, flag) \
709 ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
711 static inline int page_has_type(struct page *page)
713 return (int)page->page_type < PAGE_MAPCOUNT_RESERVE;
716 #define PAGE_TYPE_OPS(uname, lname) \
717 static __always_inline int Page##uname(struct page *page) \
719 return PageType(page, PG_##lname); \
721 static __always_inline void __SetPage##uname(struct page *page) \
723 VM_BUG_ON_PAGE(!PageType(page, 0), page); \
724 page->page_type &= ~PG_##lname; \
726 static __always_inline void __ClearPage##uname(struct page *page) \
728 VM_BUG_ON_PAGE(!Page##uname(page), page); \
729 page->page_type |= PG_##lname; \
733 * PageBuddy() indicates that the page is free and in the buddy system
734 * (see mm/page_alloc.c).
736 PAGE_TYPE_OPS(Buddy, buddy)
739 * PageOffline() indicates that the page is logically offline although the
740 * containing section is online. (e.g. inflated in a balloon driver or
741 * not onlined when onlining the section).
742 * The content of these pages is effectively stale. Such pages should not
743 * be touched (read/write/dump/save) except by their owner.
745 PAGE_TYPE_OPS(Offline, offline)
748 * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on
749 * pages allocated with __GFP_ACCOUNT. It gets cleared on page free.
751 PAGE_TYPE_OPS(Kmemcg, kmemcg)
754 * Marks pages in use as page tables.
756 PAGE_TYPE_OPS(Table, table)
759 * Marks guardpages used with debug_pagealloc.
761 PAGE_TYPE_OPS(Guard, guard)
763 extern bool is_free_buddy_page(struct page *page);
765 __PAGEFLAG(Isolated, isolated, PF_ANY);
768 * If network-based swap is enabled, sl*b must keep track of whether pages
769 * were allocated from pfmemalloc reserves.
771 static inline int PageSlabPfmemalloc(struct page *page)
773 VM_BUG_ON_PAGE(!PageSlab(page), page);
774 return PageActive(page);
777 static inline void SetPageSlabPfmemalloc(struct page *page)
779 VM_BUG_ON_PAGE(!PageSlab(page), page);
783 static inline void __ClearPageSlabPfmemalloc(struct page *page)
785 VM_BUG_ON_PAGE(!PageSlab(page), page);
786 __ClearPageActive(page);
789 static inline void ClearPageSlabPfmemalloc(struct page *page)
791 VM_BUG_ON_PAGE(!PageSlab(page), page);
792 ClearPageActive(page);
796 #define __PG_MLOCKED (1UL << PG_mlocked)
798 #define __PG_MLOCKED 0
802 * Flags checked when a page is freed. Pages being freed should not have
803 * these flags set. It they are, there is a problem.
805 #define PAGE_FLAGS_CHECK_AT_FREE \
806 (1UL << PG_lru | 1UL << PG_locked | \
807 1UL << PG_private | 1UL << PG_private_2 | \
808 1UL << PG_writeback | 1UL << PG_reserved | \
809 1UL << PG_slab | 1UL << PG_active | \
810 1UL << PG_unevictable | __PG_MLOCKED)
813 * Flags checked when a page is prepped for return by the page allocator.
814 * Pages being prepped should not have these flags set. It they are set,
815 * there has been a kernel bug or struct page corruption.
817 * __PG_HWPOISON is exceptional because it needs to be kept beyond page's
818 * alloc-free cycle to prevent from reusing the page.
820 #define PAGE_FLAGS_CHECK_AT_PREP \
821 (((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
823 #define PAGE_FLAGS_PRIVATE \
824 (1UL << PG_private | 1UL << PG_private_2)
826 * page_has_private - Determine if page has private stuff
827 * @page: The page to be checked
829 * Determine if a page has private stuff, indicating that release routines
830 * should be invoked upon it.
832 static inline int page_has_private(struct page *page)
834 return !!(page->flags & PAGE_FLAGS_PRIVATE);
841 #undef PF_NO_COMPOUND
842 #endif /* !__GENERATING_BOUNDS_H */
844 #endif /* PAGE_FLAGS_H */