/* SPDX-License-Identifier: GPL-2.0 */ /* * Macros for manipulating and testing page->flags */ #ifndef PAGE_FLAGS_H #define PAGE_FLAGS_H #include <linux/types.h> #include <linux/bug.h> #include <linux/mmdebug.h> #ifndef __GENERATING_BOUNDS_H #include <linux/mm_types.h> #include <generated/bounds.h> #endif /* !__GENERATING_BOUNDS_H */ /* * Various page->flags bits: * * PG_reserved is set for special pages. The "struct page" of such a page * should in general not be touched (e.g. set dirty) except by its owner. * Pages marked as PG_reserved include: * - Pages part of the kernel image (including vDSO) and similar (e.g. BIOS, * initrd, HW tables) * - Pages reserved or allocated early during boot (before the page allocator * was initialized). This includes (depending on the architecture) the * initial vmemmap, initial page tables, crashkernel, elfcorehdr, and much * much more. Once (if ever) freed, PG_reserved is cleared and they will * be given to the page allocator. * - Pages falling into physical memory gaps - not IORESOURCE_SYSRAM. Trying * to read/write these pages might end badly. Don't touch! * - The zero page(s) * - Pages allocated in the context of kexec/kdump (loaded kernel image, * control pages, vmcoreinfo) * - MMIO/DMA pages. Some architectures don't allow to ioremap pages that are * not marked PG_reserved (as they might be in use by somebody else who does * not respect the caching strategy). * - MCA pages on ia64 * - Pages holding CPU notes for POWER Firmware Assisted Dump * - Device memory (e.g. PMEM, DAX, HMM) * Some PG_reserved pages will be excluded from the hibernation image. * PG_reserved does in general not hinder anybody from dumping or swapping * and is no longer required for remap_pfn_range(). ioremap might require it. * Consequently, PG_reserved for a page mapped into user space can indicate * the zero page, the vDSO, MMIO pages or device memory. * * The PG_private bitflag is set on pagecache pages if they contain filesystem * specific data (which is normally at page->private). It can be used by * private allocations for its own usage. * * During initiation of disk I/O, PG_locked is set. This bit is set before I/O * and cleared when writeback _starts_ or when read _completes_. PG_writeback * is set before writeback starts and cleared when it finishes. * * PG_locked also pins a page in pagecache, and blocks truncation of the file * while it is held. * * page_waitqueue(page) is a wait queue of all tasks waiting for the page * to become unlocked. * * PG_swapbacked is set when a page uses swap as a backing storage. This are * usually PageAnon or shmem pages but please note that even anonymous pages * might lose their PG_swapbacked flag when they simply can be dropped (e.g. as * a result of MADV_FREE). * * PG_referenced, PG_reclaim are used for page reclaim for anonymous and * file-backed pagecache (see mm/vmscan.c). * * PG_error is set to indicate that an I/O error occurred on this page. * * PG_arch_1 is an architecture specific page state bit. The generic code * guarantees that this bit is cleared for a page when it first is entered into * the page cache. * * PG_hwpoison indicates that a page got corrupted in hardware and contains * data with incorrect ECC bits that triggered a machine check. Accessing is * not safe since it may cause another machine check. Don't touch! */ /* * Don't use the pageflags directly. Use the PageFoo macros. * * The page flags field is split into two parts, the main flags area * which extends from the low bits upwards, and the fields area which * extends from the high bits downwards. * * | FIELD | ... | FLAGS | * N-1 ^ 0 * (NR_PAGEFLAGS) * * The fields area is reserved for fields mapping zone, node (for NUMA) and * SPARSEMEM section (for variants of SPARSEMEM that require section ids like * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP). */ enum pageflags { … }; #define PAGEFLAGS_MASK … #ifndef __GENERATING_BOUNDS_H #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP DECLARE_STATIC_KEY_FALSE(hugetlb_optimize_vmemmap_key); /* * Return the real head page struct iff the @page is a fake head page, otherwise * return the @page itself. See Documentation/mm/vmemmap_dedup.rst. */ static __always_inline const struct page *page_fixed_fake_head(const struct page *page) { … } #else static inline const struct page *page_fixed_fake_head(const struct page *page) { return page; } #endif static __always_inline int page_is_fake_head(const struct page *page) { … } static inline unsigned long _compound_head(const struct page *page) { … } #define compound_head(page) … /** * page_folio - Converts from page to folio. * @p: The page. * * Every page is part of a folio. This function cannot be called on a * NULL pointer. * * Context: No reference, nor lock is required on @page. If the caller * does not hold a reference, this call may race with a folio split, so * it should re-check the folio still contains this page after gaining * a reference on the folio. * Return: The folio which contains this page. */ #define page_folio(p) … /** * folio_page - Return a page from a folio. * @folio: The folio. * @n: The page number to return. * * @n is relative to the start of the folio. This function does not * check that the page number lies within @folio; the caller is presumed * to have a reference to the page. */ #define folio_page(folio, n) … static __always_inline int PageTail(const struct page *page) { … } static __always_inline int PageCompound(const struct page *page) { … } #define PAGE_POISON_PATTERN … static inline int PagePoisoned(const struct page *page) { … } #ifdef CONFIG_DEBUG_VM void page_init_poison(struct page *page, size_t size); #else static inline void page_init_poison(struct page *page, size_t size) { } #endif static const unsigned long *const_folio_flags(const struct folio *folio, unsigned n) { … } static unsigned long *folio_flags(struct folio *folio, unsigned n) { … } /* * Page flags policies wrt compound pages * * PF_POISONED_CHECK * check if this struct page poisoned/uninitialized * * PF_ANY: * the page flag is relevant for small, head and tail pages. * * PF_HEAD: * for compound page all operations related to the page flag applied to * head page. * * PF_NO_TAIL: * modifications of the page flag must be done on small or head pages, * checks can be done on tail pages too. * * PF_NO_COMPOUND: * the page flag is not relevant for compound pages. * * PF_SECOND: * the page flag is stored in the first tail page. */ #define PF_POISONED_CHECK(page) … #define PF_ANY … #define PF_HEAD … #define PF_NO_TAIL … #define PF_NO_COMPOUND … #define PF_SECOND … /* Which page is the flag stored in */ #define FOLIO_PF_ANY … #define FOLIO_PF_HEAD … #define FOLIO_PF_NO_TAIL … #define FOLIO_PF_NO_COMPOUND … #define FOLIO_PF_SECOND … #define FOLIO_HEAD_PAGE … #define FOLIO_SECOND_PAGE … /* * Macros to create function definitions for page flags */ #define FOLIO_TEST_FLAG(name, page) … #define FOLIO_SET_FLAG(name, page) … #define FOLIO_CLEAR_FLAG(name, page) … #define __FOLIO_SET_FLAG(name, page) … #define __FOLIO_CLEAR_FLAG(name, page) … #define FOLIO_TEST_SET_FLAG(name, page) … #define FOLIO_TEST_CLEAR_FLAG(name, page) … #define FOLIO_FLAG(name, page) … #define TESTPAGEFLAG(uname, lname, policy) … #define SETPAGEFLAG(uname, lname, policy) … #define CLEARPAGEFLAG(uname, lname, policy) … #define __SETPAGEFLAG(uname, lname, policy) … #define __CLEARPAGEFLAG(uname, lname, policy) … #define TESTSETFLAG(uname, lname, policy) … #define TESTCLEARFLAG(uname, lname, policy) … #define PAGEFLAG(uname, lname, policy) … #define __PAGEFLAG(uname, lname, policy) … #define TESTSCFLAG(uname, lname, policy) … #define FOLIO_TEST_FLAG_FALSE(name) … #define FOLIO_SET_FLAG_NOOP(name) … #define FOLIO_CLEAR_FLAG_NOOP(name) … #define __FOLIO_SET_FLAG_NOOP(name) … #define __FOLIO_CLEAR_FLAG_NOOP(name) … #define FOLIO_TEST_SET_FLAG_FALSE(name) … #define FOLIO_TEST_CLEAR_FLAG_FALSE(name) … #define FOLIO_FLAG_FALSE(name) … #define TESTPAGEFLAG_FALSE(uname, lname) … #define SETPAGEFLAG_NOOP(uname, lname) … #define CLEARPAGEFLAG_NOOP(uname, lname) … #define __CLEARPAGEFLAG_NOOP(uname, lname) … #define TESTSETFLAG_FALSE(uname, lname) … #define TESTCLEARFLAG_FALSE(uname, lname) … #define PAGEFLAG_FALSE(uname, lname) … #define TESTSCFLAG_FALSE(uname, lname) … __PAGEFLAG(…) FOLIO_FLAG(…) PAGEFLAG(…) TESTCLEARFLAG(…) FOLIO_FLAG(…) FOLIO_TEST_CLEAR_FLAG(…) __FOLIO_SET_FLAG(…) PAGEFLAG(…) TESTSCFLAG(…) __CLEARPAGEFLAG(…) PAGEFLAG(…) __CLEARPAGEFLAG(…) TESTCLEARFLAG(…) PAGEFLAG(…) __CLEARPAGEFLAG(…) TESTCLEARFLAG(…) PAGEFLAG(…) TESTCLEARFLAG(…) PAGEFLAG(…) /* Used by some filesystems */ /* Xen */ PAGEFLAG(…) TESTSCFLAG(…) PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND); PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND); PAGEFLAG(…) TESTCLEARFLAG(…) PAGEFLAG(…) __CLEARPAGEFLAG(…) __SETPAGEFLAG(…) PAGEFLAG(…) __CLEARPAGEFLAG(…) __SETPAGEFLAG(…) /* * Private page markings that may be used by the filesystem that owns the page * for its own purposes. * - PG_private and PG_private_2 cause release_folio() and co to be invoked */ PAGEFLAG(…) PAGEFLAG(…) TESTSCFLAG(…) PAGEFLAG(…) TESTCLEARFLAG(…) /* * Only test-and-set exist for PG_writeback. The unconditional operators are * risky: they bypass page accounting. */ TESTPAGEFLAG(…) TESTSCFLAG(…) PAGEFLAG(…) /* PG_readahead is only used for reads; PG_reclaim is only for writes */ PAGEFLAG(…) TESTCLEARFLAG(…) PAGEFLAG(…) TESTCLEARFLAG(…) #ifdef CONFIG_HIGHMEM /* * Must use a macro here due to header dependency issues. page_zone() is not * available at this point. */ #define PageHighMem … #define folio_test_highmem … #else PAGEFLAG_FALSE(HighMem, highmem) #endif #ifdef CONFIG_SWAP static __always_inline bool folio_test_swapcache(const struct folio *folio) { … } static __always_inline bool PageSwapCache(const struct page *page) { … } SETPAGEFLAG(…) CLEARPAGEFLAG(…) #else PAGEFLAG_FALSE(SwapCache, swapcache) #endif PAGEFLAG(…) __CLEARPAGEFLAG(…) TESTCLEARFLAG(…) #ifdef CONFIG_MMU PAGEFLAG(…) __CLEARPAGEFLAG(…) TESTSCFLAG(…) #else PAGEFLAG_FALSE(Mlocked, mlocked) __CLEARPAGEFLAG_NOOP(Mlocked, mlocked) TESTSCFLAG_FALSE(Mlocked, mlocked) #endif #ifdef CONFIG_ARCH_USES_PG_UNCACHED PAGEFLAG(…) #else PAGEFLAG_FALSE(Uncached, uncached) #endif #ifdef CONFIG_MEMORY_FAILURE PAGEFLAG(…) TESTSCFLAG(…) #define __PG_HWPOISON … #else PAGEFLAG_FALSE(HWPoison, hwpoison) #define __PG_HWPOISON … #endif #ifdef CONFIG_PAGE_IDLE_FLAG #ifdef CONFIG_64BIT FOLIO_TEST_FLAG(…) FOLIO_SET_FLAG(…) FOLIO_TEST_CLEAR_FLAG(…) FOLIO_FLAG(…) #endif /* See page_idle.h for !64BIT workaround */ #else /* !CONFIG_PAGE_IDLE_FLAG */ FOLIO_FLAG_FALSE(young) FOLIO_TEST_CLEAR_FLAG_FALSE(young) FOLIO_FLAG_FALSE(idle) #endif /* * PageReported() is used to track reported free pages within the Buddy * allocator. We can use the non-atomic version of the test and set * operations as both should be shielded with the zone lock to prevent * any possible races on the setting or clearing of the bit. */ __PAGEFLAG(…) #ifdef CONFIG_MEMORY_HOTPLUG PAGEFLAG(…) #else PAGEFLAG_FALSE(VmemmapSelfHosted, vmemmap_self_hosted) #endif /* * On an anonymous folio mapped into a user virtual memory area, * folio->mapping points to its anon_vma, not to a struct address_space; * with the PAGE_MAPPING_ANON bit set to distinguish it. See rmap.h. * * On an anonymous page in a VM_MERGEABLE area, if CONFIG_KSM is enabled, * the PAGE_MAPPING_MOVABLE bit may be set along with the PAGE_MAPPING_ANON * bit; and then folio->mapping points, not to an anon_vma, but to a private * structure which KSM associates with that merged page. See ksm.h. * * PAGE_MAPPING_KSM without PAGE_MAPPING_ANON is used for non-lru movable * page and then folio->mapping points to a struct movable_operations. * * Please note that, confusingly, "folio_mapping" refers to the inode * address_space which maps the folio from disk; whereas "folio_mapped" * refers to user virtual address space into which the folio is mapped. * * For slab pages, since slab reuses the bits in struct page to store its * internal states, the folio->mapping does not exist as such, nor do * these flags below. So in order to avoid testing non-existent bits, * please make sure that folio_test_slab(folio) actually evaluates to * false before calling the following functions (e.g., folio_test_anon). * See mm/slab.h. */ #define PAGE_MAPPING_ANON … #define PAGE_MAPPING_MOVABLE … #define PAGE_MAPPING_KSM … #define PAGE_MAPPING_FLAGS … /* * Different with flags above, this flag is used only for fsdax mode. It * indicates that this page->mapping is now under reflink case. */ #define PAGE_MAPPING_DAX_SHARED … static __always_inline bool folio_mapping_flags(const struct folio *folio) { … } static __always_inline bool PageMappingFlags(const struct page *page) { … } static __always_inline bool folio_test_anon(const struct folio *folio) { … } static __always_inline bool PageAnon(const struct page *page) { … } static __always_inline bool __folio_test_movable(const struct folio *folio) { … } static __always_inline bool __PageMovable(const struct page *page) { … } #ifdef CONFIG_KSM /* * A KSM page is one of those write-protected "shared pages" or "merged pages" * which KSM maps into multiple mms, wherever identical anonymous page content * is found in VM_MERGEABLE vmas. It's a PageAnon page, pointing not to any * anon_vma, but to that page's node of the stable tree. */ static __always_inline bool folio_test_ksm(const struct folio *folio) { … } static __always_inline bool PageKsm(const struct page *page) { … } #else TESTPAGEFLAG_FALSE(Ksm, ksm) #endif u64 stable_page_flags(const struct page *page); /** * folio_xor_flags_has_waiters - Change some folio flags. * @folio: The folio. * @mask: Bits set in this word will be changed. * * This must only be used for flags which are changed with the folio * lock held. For example, it is unsafe to use for PG_dirty as that * can be set without the folio lock held. It can also only be used * on flags which are in the range 0-6 as some of the implementations * only affect those bits. * * Return: Whether there are tasks waiting on the folio. */ static inline bool folio_xor_flags_has_waiters(struct folio *folio, unsigned long mask) { … } /** * folio_test_uptodate - Is this folio up to date? * @folio: The folio. * * The uptodate flag is set on a folio when every byte in the folio is * at least as new as the corresponding bytes on storage. Anonymous * and CoW folios are always uptodate. If the folio is not uptodate, * some of the bytes in it may be; see the is_partially_uptodate() * address_space operation. */ static inline bool folio_test_uptodate(const struct folio *folio) { … } static inline bool PageUptodate(const struct page *page) { … } static __always_inline void __folio_mark_uptodate(struct folio *folio) { … } static __always_inline void folio_mark_uptodate(struct folio *folio) { … } static __always_inline void __SetPageUptodate(struct page *page) { … } static __always_inline void SetPageUptodate(struct page *page) { … } CLEARPAGEFLAG(…) void __folio_start_writeback(struct folio *folio, bool keep_write); void set_page_writeback(struct page *page); #define folio_start_writeback(folio) … #define folio_start_writeback_keepwrite(folio) … static __always_inline bool folio_test_head(const struct folio *folio) { … } static __always_inline int PageHead(const struct page *page) { … } __SETPAGEFLAG(…) __CLEARPAGEFLAG(…) CLEARPAGEFLAG(…) /** * folio_test_large() - Does this folio contain more than one page? * @folio: The folio to test. * * Return: True if the folio is larger than one page. */ static inline bool folio_test_large(const struct folio *folio) { … } static __always_inline void set_compound_head(struct page *page, struct page *head) { … } static __always_inline void clear_compound_head(struct page *page) { … } #ifdef CONFIG_TRANSPARENT_HUGEPAGE static inline void ClearPageCompound(struct page *page) { … } FOLIO_FLAG(…) #else FOLIO_FLAG_FALSE(large_rmappable) #endif #define PG_head_mask … #ifdef CONFIG_TRANSPARENT_HUGEPAGE /* * PageHuge() only returns true for hugetlbfs pages, but not for * normal or transparent huge pages. * * PageTransHuge() returns true for both transparent huge and * hugetlbfs pages, but not normal pages. PageTransHuge() can only be * called only in the core VM paths where hugetlbfs pages can't exist. */ static inline int PageTransHuge(const struct page *page) { … } /* * PageTransCompound returns true for both transparent huge pages * and hugetlbfs pages, so it should only be called when it's known * that hugetlbfs pages aren't involved. */ static inline int PageTransCompound(const struct page *page) { … } /* * PageTransTail returns true for both transparent huge pages * and hugetlbfs pages, so it should only be called when it's known * that hugetlbfs pages aren't involved. */ static inline int PageTransTail(const struct page *page) { … } #else TESTPAGEFLAG_FALSE(TransHuge, transhuge) TESTPAGEFLAG_FALSE(TransCompound, transcompound) TESTPAGEFLAG_FALSE(TransCompoundMap, transcompoundmap) TESTPAGEFLAG_FALSE(TransTail, transtail) #endif #if defined(CONFIG_MEMORY_FAILURE) && defined(CONFIG_TRANSPARENT_HUGEPAGE) /* * PageHasHWPoisoned indicates that at least one subpage is hwpoisoned in the * compound page. * * This flag is set by hwpoison handler. Cleared by THP split or free page. */ PAGEFLAG(…) TESTSCFLAG(…) #else PAGEFLAG_FALSE(HasHWPoisoned, has_hwpoisoned) TESTSCFLAG_FALSE(HasHWPoisoned, has_hwpoisoned) #endif /* * For pages that are never mapped to userspace, * page_type may be used. Because it is initialised to -1, we invert the * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and * __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and * low bits so that an underflow or overflow of _mapcount won't be * mistaken for a page type value. */ enum pagetype { … }; #define PageType(page, flag) … #define folio_test_type(folio, flag) … static inline int page_type_has_type(unsigned int page_type) { … } static inline int page_has_type(const struct page *page) { … } #define FOLIO_TYPE_OPS(lname, fname) … #define PAGE_TYPE_OPS(uname, lname, fname) … /* * PageBuddy() indicates that the page is free and in the buddy system * (see mm/page_alloc.c). */ PAGE_TYPE_OPS(…) /* * PageOffline() indicates that the page is logically offline although the * containing section is online. (e.g. inflated in a balloon driver or * not onlined when onlining the section). * The content of these pages is effectively stale. Such pages should not * be touched (read/write/dump/save) except by their owner. * * When a memory block gets onlined, all pages are initialized with a * refcount of 1 and PageOffline(). generic_online_page() will * take care of clearing PageOffline(). * * If a driver wants to allow to offline unmovable PageOffline() pages without * putting them back to the buddy, it can do so via the memory notifier by * decrementing the reference count in MEM_GOING_OFFLINE and incrementing the * reference count in MEM_CANCEL_OFFLINE. When offlining, the PageOffline() * pages (now with a reference count of zero) are treated like free (unmanaged) * pages, allowing the containing memory block to get offlined. A driver that * relies on this feature is aware that re-onlining the memory block will * require not giving them to the buddy via generic_online_page(). * * Memory offlining code will not adjust the managed page count for any * PageOffline() pages, treating them like they were never exposed to the * buddy using generic_online_page(). * * There are drivers that mark a page PageOffline() and expect there won't be * any further access to page content. PFN walkers that read content of random * pages should check PageOffline() and synchronize with such drivers using * page_offline_freeze()/page_offline_thaw(). */ PAGE_TYPE_OPS(…) extern void page_offline_freeze(void); extern void page_offline_thaw(void); extern void page_offline_begin(void); extern void page_offline_end(void); /* * Marks pages in use as page tables. */ PAGE_TYPE_OPS(…) /* * Marks guardpages used with debug_pagealloc. */ PAGE_TYPE_OPS(…) FOLIO_TYPE_OPS(…) /** * PageSlab - Determine if the page belongs to the slab allocator * @page: The page to test. * * Context: Any context. * Return: True for slab pages, false for any other kind of page. */ static inline bool PageSlab(const struct page *page) { … } #ifdef CONFIG_HUGETLB_PAGE FOLIO_TYPE_OPS(…) #else FOLIO_TEST_FLAG_FALSE(hugetlb) #endif PAGE_TYPE_OPS(…) /** * PageHuge - Determine if the page belongs to hugetlbfs * @page: The page to test. * * Context: Any context. * Return: True for hugetlbfs pages, false for anon pages or pages * belonging to other filesystems. */ static inline bool PageHuge(const struct page *page) { … } /* * Check if a page is currently marked HWPoisoned. Note that this check is * best effort only and inherently racy: there is no way to synchronize with * failing hardware. */ static inline bool is_page_hwpoison(const struct page *page) { … } bool is_free_buddy_page(const struct page *page); PAGEFLAG(Isolated, isolated, PF_ANY); static __always_inline int PageAnonExclusive(const struct page *page) { … } static __always_inline void SetPageAnonExclusive(struct page *page) { … } static __always_inline void ClearPageAnonExclusive(struct page *page) { … } static __always_inline void __ClearPageAnonExclusive(struct page *page) { … } #ifdef CONFIG_MMU #define __PG_MLOCKED … #else #define __PG_MLOCKED … #endif /* * Flags checked when a page is freed. Pages being freed should not have * these flags set. If they are, there is a problem. */ #define PAGE_FLAGS_CHECK_AT_FREE … /* * Flags checked when a page is prepped for return by the page allocator. * Pages being prepped should not have these flags set. If they are set, * there has been a kernel bug or struct page corruption. * * __PG_HWPOISON is exceptional because it needs to be kept beyond page's * alloc-free cycle to prevent from reusing the page. */ #define PAGE_FLAGS_CHECK_AT_PREP … /* * Flags stored in the second page of a compound page. They may overlap * the CHECK_AT_FREE flags above, so need to be cleared. */ #define PAGE_FLAGS_SECOND … #define PAGE_FLAGS_PRIVATE … /** * page_has_private - Determine if page has private stuff * @page: The page to be checked * * Determine if a page has private stuff, indicating that release routines * should be invoked upon it. */ static inline int page_has_private(const struct page *page) { … } static inline bool folio_has_private(const struct folio *folio) { … } #undef PF_ANY #undef PF_HEAD #undef PF_NO_TAIL #undef PF_NO_COMPOUND #undef PF_SECOND #endif /* !__GENERATING_BOUNDS_H */ #endif /* PAGE_FLAGS_H */
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