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Diffstat (limited to 'include/linux/page-flags.h')
| -rw-r--r-- | include/linux/page-flags.h | 1218 |
1 files changed, 1218 insertions, 0 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h new file mode 100644 index 000000000..7a863572a --- /dev/null +++ b/include/linux/page-flags.h @@ -0,0 +1,1218 @@ +/* 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_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 { + PG_locked, /* Page is locked. Don't touch. */ + PG_writeback, /* Page is under writeback */ + PG_referenced, + PG_uptodate, + PG_dirty, + PG_lru, + PG_head, /* Must be in bit 6 */ + PG_waiters, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */ + PG_active, + PG_workingset, + PG_owner_priv_1, /* Owner use. If pagecache, fs may use */ + PG_owner_2, /* Owner use. If pagecache, fs may use */ + PG_arch_1, + PG_reserved, + PG_private, /* If pagecache, has fs-private data */ + PG_private_2, /* If pagecache, has fs aux data */ + PG_reclaim, /* To be reclaimed asap */ + PG_swapbacked, /* Page is backed by RAM/swap */ + PG_unevictable, /* Page is "unevictable" */ + PG_dropbehind, /* drop pages on IO completion */ +#ifdef CONFIG_MMU + PG_mlocked, /* Page is vma mlocked */ +#endif +#ifdef CONFIG_MEMORY_FAILURE + PG_hwpoison, /* hardware poisoned page. Don't touch */ +#endif +#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT) + PG_young, + PG_idle, +#endif +#ifdef CONFIG_ARCH_USES_PG_ARCH_2 + PG_arch_2, +#endif +#ifdef CONFIG_ARCH_USES_PG_ARCH_3 + PG_arch_3, +#endif + __NR_PAGEFLAGS, + + PG_readahead = PG_reclaim, + + /* Anonymous memory (and shmem) */ + PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */ + /* Some filesystems */ + PG_checked = PG_owner_priv_1, + + /* + * Depending on the way an anonymous folio can be mapped into a page + * table (e.g., single PMD/PUD/CONT of the head page vs. PTE-mapped + * THP), PG_anon_exclusive may be set only for the head page or for + * tail pages of an anonymous folio. For now, we only expect it to be + * set on tail pages for PTE-mapped THP. + */ + PG_anon_exclusive = PG_owner_2, + + /* + * Set if all buffer heads in the folio are mapped. + * Filesystems which do not use BHs can use it for their own purpose. + */ + PG_mappedtodisk = PG_owner_2, + + /* Two page bits are conscripted by FS-Cache to maintain local caching + * state. These bits are set on pages belonging to the netfs's inodes + * when those inodes are being locally cached. + */ + PG_fscache = PG_private_2, /* page backed by cache */ + + /* XEN */ + /* Pinned in Xen as a read-only pagetable page. */ + PG_pinned = PG_owner_priv_1, + /* Pinned as part of domain save (see xen_mm_pin_all()). */ + PG_savepinned = PG_dirty, + /* Has a grant mapping of another (foreign) domain's page. */ + PG_foreign = PG_owner_priv_1, + /* Remapped by swiotlb-xen. */ + PG_xen_remapped = PG_owner_priv_1, + +#ifdef CONFIG_MIGRATION + /* movable_ops page that is isolated for migration */ + PG_movable_ops_isolated = PG_reclaim, + /* this is a movable_ops page (for selected typed pages only) */ + PG_movable_ops = PG_uptodate, +#endif + + /* Only valid for buddy pages. Used to track pages that are reported */ + PG_reported = PG_uptodate, + +#ifdef CONFIG_MEMORY_HOTPLUG + /* For self-hosted memmap pages */ + PG_vmemmap_self_hosted = PG_owner_priv_1, +#endif + + /* + * Flags only valid for compound pages. Stored in first tail page's + * flags word. Cannot use the first 8 flags or any flag marked as + * PF_ANY. + */ + + /* At least one page in this folio has the hwpoison flag set */ + PG_has_hwpoisoned = PG_active, + PG_large_rmappable = PG_workingset, /* anon or file-backed */ + PG_partially_mapped = PG_reclaim, /* was identified to be partially mapped */ +}; + +#define PAGEFLAGS_MASK ((1UL << NR_PAGEFLAGS) - 1) + +#ifndef __GENERATING_BOUNDS_H + +/* + * For tail pages, if the size of struct page is power-of-2 ->compound_info + * encodes the mask that converts the address of the tail page address to + * the head page address. + * + * Otherwise, ->compound_info has direct pointer to head pages. + */ +static __always_inline bool compound_info_has_mask(void) +{ + /* + * Limit mask usage to HugeTLB vmemmap optimization (HVO) where it + * makes a difference. + * + * The approach with mask would work in the wider set of conditions, + * but it requires validating that struct pages are naturally aligned + * for all orders up to the MAX_FOLIO_ORDER, which can be tricky. + */ + if (!IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP)) + return false; + + return is_power_of_2(sizeof(struct page)); +} + +static __always_inline unsigned long _compound_head(const struct page *page) +{ + unsigned long info = READ_ONCE(page->compound_info); + unsigned long mask; + + if (!compound_info_has_mask()) { + /* Bit 0 encodes PageTail() */ + if (info & 1) + return info - 1; + + return (unsigned long)page; + } + + /* + * If compound_info_has_mask() is true the rest of the info encodes + * the mask that converts the address of the tail page to the head page. + * + * No need to clear bit 0 in the mask as 'page' always has it clear. + * + * Let's do it in a branchless manner. + */ + + /* Non-tail: -1UL, Tail: 0 */ + mask = (info & 1) - 1; + + /* Non-tail: -1UL, Tail: info */ + mask |= info; + + return (unsigned long)page & mask; +} + +#define compound_head(page) ((typeof(page))_compound_head(page)) + +static __always_inline void set_compound_head(struct page *tail, + const struct page *head, unsigned int order) +{ + unsigned int shift; + unsigned long mask; + + if (!compound_info_has_mask()) { + WRITE_ONCE(tail->compound_info, (unsigned long)head | 1); + return; + } + + /* + * If the size of struct page is power-of-2, bits [shift:0] of the + * virtual address of compound head are zero. + * + * Calculate mask that can be applied to the virtual address of + * the tail page to get address of the head page. + */ + shift = order + order_base_2(sizeof(struct page)); + mask = GENMASK(BITS_PER_LONG - 1, shift); + + /* Bit 0 encodes PageTail() */ + WRITE_ONCE(tail->compound_info, mask | 1); +} + +static __always_inline void clear_compound_head(struct page *page) +{ + WRITE_ONCE(page->compound_info, 0); +} + +/** + * 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) (_Generic((p), \ + const struct page *: (const struct folio *)_compound_head(p), \ + struct page *: (struct folio *)_compound_head(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) (&(folio)->page + (n)) + +static __always_inline int PageTail(const struct page *page) +{ + return READ_ONCE(page->compound_info) & 1; +} + +static __always_inline int PageCompound(const struct page *page) +{ + return test_bit(PG_head, &page->flags.f) || + READ_ONCE(page->compound_info) & 1; +} + +#define PAGE_POISON_PATTERN -1l +static inline int PagePoisoned(const struct page *page) +{ + return READ_ONCE(page->flags.f) == PAGE_POISON_PATTERN; +} + +#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) +{ + const struct page *page = &folio->page; + + VM_BUG_ON_PGFLAGS(page->compound_info & 1, page); + VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags.f), page); + return &page[n].flags.f; +} + +static unsigned long *folio_flags(struct folio *folio, unsigned n) +{ + struct page *page = &folio->page; + + VM_BUG_ON_PGFLAGS(page->compound_info & 1, page); + VM_BUG_ON_PGFLAGS(n > 0 && !test_bit(PG_head, &page->flags.f), page); + return &page[n].flags.f; +} + +/* + * 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) ({ \ + VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \ + page; }) +#define PF_ANY(page, enforce) PF_POISONED_CHECK(page) +#define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page)) +#define PF_NO_TAIL(page, enforce) ({ \ + VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \ + PF_POISONED_CHECK(compound_head(page)); }) +#define PF_NO_COMPOUND(page, enforce) ({ \ + VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \ + PF_POISONED_CHECK(page); }) +#define PF_SECOND(page, enforce) ({ \ + VM_BUG_ON_PGFLAGS(!PageHead(page), page); \ + PF_POISONED_CHECK(&page[1]); }) + +/* Which page is the flag stored in */ +#define FOLIO_PF_ANY 0 +#define FOLIO_PF_HEAD 0 +#define FOLIO_PF_NO_TAIL 0 +#define FOLIO_PF_NO_COMPOUND 0 +#define FOLIO_PF_SECOND 1 + +#define FOLIO_HEAD_PAGE 0 +#define FOLIO_SECOND_PAGE 1 + +/* + * Macros to create function definitions for page flags + */ +#define FOLIO_TEST_FLAG(name, page) \ +static __always_inline bool folio_test_##name(const struct folio *folio) \ +{ return test_bit(PG_##name, const_folio_flags(folio, page)); } + +#define FOLIO_SET_FLAG(name, page) \ +static __always_inline void folio_set_##name(struct folio *folio) \ +{ set_bit(PG_##name, folio_flags(folio, page)); } + +#define FOLIO_CLEAR_FLAG(name, page) \ +static __always_inline void folio_clear_##name(struct folio *folio) \ +{ clear_bit(PG_##name, folio_flags(folio, page)); } + +#define __FOLIO_SET_FLAG(name, page) \ +static __always_inline void __folio_set_##name(struct folio *folio) \ +{ __set_bit(PG_##name, folio_flags(folio, page)); } + +#define __FOLIO_CLEAR_FLAG(name, page) \ +static __always_inline void __folio_clear_##name(struct folio *folio) \ +{ __clear_bit(PG_##name, folio_flags(folio, page)); } + +#define FOLIO_TEST_SET_FLAG(name, page) \ +static __always_inline bool folio_test_set_##name(struct folio *folio) \ +{ return test_and_set_bit(PG_##name, folio_flags(folio, page)); } + +#define FOLIO_TEST_CLEAR_FLAG(name, page) \ +static __always_inline bool folio_test_clear_##name(struct folio *folio) \ +{ return test_and_clear_bit(PG_##name, folio_flags(folio, page)); } + +#define FOLIO_FLAG(name, page) \ +FOLIO_TEST_FLAG(name, page) \ +FOLIO_SET_FLAG(name, page) \ +FOLIO_CLEAR_FLAG(name, page) + +#define TESTPAGEFLAG(uname, lname, policy) \ +FOLIO_TEST_FLAG(lname, FOLIO_##policy) \ +static __always_inline int Page##uname(const struct page *page) \ +{ return test_bit(PG_##lname, &policy(page, 0)->flags.f); } + +#define SETPAGEFLAG(uname, lname, policy) \ +FOLIO_SET_FLAG(lname, FOLIO_##policy) \ +static __always_inline void SetPage##uname(struct page *page) \ +{ set_bit(PG_##lname, &policy(page, 1)->flags.f); } + +#define CLEARPAGEFLAG(uname, lname, policy) \ +FOLIO_CLEAR_FLAG(lname, FOLIO_##policy) \ +static __always_inline void ClearPage##uname(struct page *page) \ +{ clear_bit(PG_##lname, &policy(page, 1)->flags.f); } + +#define __SETPAGEFLAG(uname, lname, policy) \ +__FOLIO_SET_FLAG(lname, FOLIO_##policy) \ +static __always_inline void __SetPage##uname(struct page *page) \ +{ __set_bit(PG_##lname, &policy(page, 1)->flags.f); } + +#define __CLEARPAGEFLAG(uname, lname, policy) \ +__FOLIO_CLEAR_FLAG(lname, FOLIO_##policy) \ +static __always_inline void __ClearPage##uname(struct page *page) \ +{ __clear_bit(PG_##lname, &policy(page, 1)->flags.f); } + +#define TESTSETFLAG(uname, lname, policy) \ +FOLIO_TEST_SET_FLAG(lname, FOLIO_##policy) \ +static __always_inline int TestSetPage##uname(struct page *page) \ +{ return test_and_set_bit(PG_##lname, &policy(page, 1)->flags.f); } + +#define TESTCLEARFLAG(uname, lname, policy) \ +FOLIO_TEST_CLEAR_FLAG(lname, FOLIO_##policy) \ +static __always_inline int TestClearPage##uname(struct page *page) \ +{ return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags.f); } + +#define PAGEFLAG(uname, lname, policy) \ + TESTPAGEFLAG(uname, lname, policy) \ + SETPAGEFLAG(uname, lname, policy) \ + CLEARPAGEFLAG(uname, lname, policy) + +#define __PAGEFLAG(uname, lname, policy) \ + TESTPAGEFLAG(uname, lname, policy) \ + __SETPAGEFLAG(uname, lname, policy) \ + __CLEARPAGEFLAG(uname, lname, policy) + +#define TESTSCFLAG(uname, lname, policy) \ + TESTSETFLAG(uname, lname, policy) \ + TESTCLEARFLAG(uname, lname, policy) + +#define FOLIO_TEST_FLAG_FALSE(name) \ +static inline bool folio_test_##name(const struct folio *folio) \ +{ return false; } +#define FOLIO_SET_FLAG_NOOP(name) \ +static inline void folio_set_##name(struct folio *folio) { } +#define FOLIO_CLEAR_FLAG_NOOP(name) \ +static inline void folio_clear_##name(struct folio *folio) { } +#define __FOLIO_SET_FLAG_NOOP(name) \ +static inline void __folio_set_##name(struct folio *folio) { } +#define __FOLIO_CLEAR_FLAG_NOOP(name) \ +static inline void __folio_clear_##name(struct folio *folio) { } +#define FOLIO_TEST_SET_FLAG_FALSE(name) \ +static inline bool folio_test_set_##name(struct folio *folio) \ +{ return false; } +#define FOLIO_TEST_CLEAR_FLAG_FALSE(name) \ +static inline bool folio_test_clear_##name(struct folio *folio) \ +{ return false; } + +#define FOLIO_FLAG_FALSE(name) \ +FOLIO_TEST_FLAG_FALSE(name) \ +FOLIO_SET_FLAG_NOOP(name) \ +FOLIO_CLEAR_FLAG_NOOP(name) + +#define TESTPAGEFLAG_FALSE(uname, lname) \ +FOLIO_TEST_FLAG_FALSE(lname) \ +static inline int Page##uname(const struct page *page) { return 0; } + +#define SETPAGEFLAG_NOOP(uname, lname) \ +FOLIO_SET_FLAG_NOOP(lname) \ +static inline void SetPage##uname(struct page *page) { } + +#define CLEARPAGEFLAG_NOOP(uname, lname) \ +FOLIO_CLEAR_FLAG_NOOP(lname) \ +static inline void ClearPage##uname(struct page *page) { } + +#define __CLEARPAGEFLAG_NOOP(uname, lname) \ +__FOLIO_CLEAR_FLAG_NOOP(lname) \ +static inline void __ClearPage##uname(struct page *page) { } + +#define TESTSETFLAG_FALSE(uname, lname) \ +FOLIO_TEST_SET_FLAG_FALSE(lname) \ +static inline int TestSetPage##uname(struct page *page) { return 0; } + +#define TESTCLEARFLAG_FALSE(uname, lname) \ +FOLIO_TEST_CLEAR_FLAG_FALSE(lname) \ +static inline int TestClearPage##uname(struct page *page) { return 0; } + +#define PAGEFLAG_FALSE(uname, lname) TESTPAGEFLAG_FALSE(uname, lname) \ + SETPAGEFLAG_NOOP(uname, lname) CLEARPAGEFLAG_NOOP(uname, lname) + +#define TESTSCFLAG_FALSE(uname, lname) \ + TESTSETFLAG_FALSE(uname, lname) TESTCLEARFLAG_FALSE(uname, lname) + +__PAGEFLAG(Locked, locked, PF_NO_TAIL) +FOLIO_FLAG(waiters, FOLIO_HEAD_PAGE) +FOLIO_FLAG(referenced, FOLIO_HEAD_PAGE) + FOLIO_TEST_CLEAR_FLAG(referenced, FOLIO_HEAD_PAGE) + __FOLIO_SET_FLAG(referenced, FOLIO_HEAD_PAGE) +PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD) + __CLEARPAGEFLAG(Dirty, dirty, PF_HEAD) +PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD) + TESTCLEARFLAG(LRU, lru, PF_HEAD) +FOLIO_FLAG(active, FOLIO_HEAD_PAGE) + __FOLIO_CLEAR_FLAG(active, FOLIO_HEAD_PAGE) + FOLIO_TEST_CLEAR_FLAG(active, FOLIO_HEAD_PAGE) +PAGEFLAG(Workingset, workingset, PF_HEAD) + TESTCLEARFLAG(Workingset, workingset, PF_HEAD) +PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */ + +/* Xen */ +PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND) + TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND) +PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND); +PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND); +PAGEFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND) + TESTCLEARFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND) + +PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) + __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) + __SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND) +FOLIO_FLAG(swapbacked, FOLIO_HEAD_PAGE) + __FOLIO_CLEAR_FLAG(swapbacked, FOLIO_HEAD_PAGE) + __FOLIO_SET_FLAG(swapbacked, FOLIO_HEAD_PAGE) + +/* + * 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(Private, private, PF_ANY) +FOLIO_FLAG(private_2, FOLIO_HEAD_PAGE) + +/* owner_2 can be set on tail pages for anon memory */ +FOLIO_FLAG(owner_2, FOLIO_HEAD_PAGE) + +/* + * Only test-and-set exist for PG_writeback. The unconditional operators are + * risky: they bypass page accounting. + */ +TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL) + TESTSCFLAG(Writeback, writeback, PF_NO_TAIL) +FOLIO_FLAG(mappedtodisk, FOLIO_HEAD_PAGE) + +/* PG_readahead is only used for reads; PG_reclaim is only for writes */ +PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL) + TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL) +FOLIO_FLAG(readahead, FOLIO_HEAD_PAGE) + FOLIO_TEST_CLEAR_FLAG(readahead, FOLIO_HEAD_PAGE) + +FOLIO_FLAG(dropbehind, FOLIO_HEAD_PAGE) + FOLIO_TEST_CLEAR_FLAG(dropbehind, FOLIO_HEAD_PAGE) + __FOLIO_SET_FLAG(dropbehind, FOLIO_HEAD_PAGE) + +#ifdef CONFIG_HIGHMEM +/* + * Must use a macro here due to header dependency issues. page_zone() is not + * available at this point. + */ +#define PageHighMem(__p) is_highmem_idx(page_zonenum(__p)) +#define folio_test_highmem(__f) is_highmem_idx(folio_zonenum(__f)) +#else +PAGEFLAG_FALSE(HighMem, highmem) +#endif +#define PhysHighMem(__p) (PageHighMem(phys_to_page(__p))) + +/* Does kmap_local_folio() only allow access to one page of the folio? */ +#ifdef CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP +#define folio_test_partial_kmap(f) true +#else +#define folio_test_partial_kmap(f) folio_test_highmem(f) +#endif + +#ifdef CONFIG_SWAP +static __always_inline bool folio_test_swapcache(const struct folio *folio) +{ + return folio_test_swapbacked(folio) && + test_bit(PG_swapcache, const_folio_flags(folio, 0)); +} + +FOLIO_SET_FLAG(swapcache, FOLIO_HEAD_PAGE) +FOLIO_CLEAR_FLAG(swapcache, FOLIO_HEAD_PAGE) +#else +FOLIO_FLAG_FALSE(swapcache) +#endif + +FOLIO_FLAG(unevictable, FOLIO_HEAD_PAGE) + __FOLIO_CLEAR_FLAG(unevictable, FOLIO_HEAD_PAGE) + FOLIO_TEST_CLEAR_FLAG(unevictable, FOLIO_HEAD_PAGE) + +#ifdef CONFIG_MMU +FOLIO_FLAG(mlocked, FOLIO_HEAD_PAGE) + __FOLIO_CLEAR_FLAG(mlocked, FOLIO_HEAD_PAGE) + FOLIO_TEST_CLEAR_FLAG(mlocked, FOLIO_HEAD_PAGE) + FOLIO_TEST_SET_FLAG(mlocked, FOLIO_HEAD_PAGE) +#else +FOLIO_FLAG_FALSE(mlocked) + __FOLIO_CLEAR_FLAG_NOOP(mlocked) + FOLIO_TEST_CLEAR_FLAG_FALSE(mlocked) + FOLIO_TEST_SET_FLAG_FALSE(mlocked) +#endif + +#ifdef CONFIG_MEMORY_FAILURE +PAGEFLAG(HWPoison, hwpoison, PF_ANY) +TESTSCFLAG(HWPoison, hwpoison, PF_ANY) +#define __PG_HWPOISON (1UL << PG_hwpoison) +#else +PAGEFLAG_FALSE(HWPoison, hwpoison) +#define __PG_HWPOISON 0 +#endif + +#ifdef CONFIG_PAGE_IDLE_FLAG +#ifdef CONFIG_64BIT +FOLIO_TEST_FLAG(young, FOLIO_HEAD_PAGE) +FOLIO_SET_FLAG(young, FOLIO_HEAD_PAGE) +FOLIO_TEST_CLEAR_FLAG(young, FOLIO_HEAD_PAGE) +FOLIO_FLAG(idle, FOLIO_HEAD_PAGE) +#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(Reported, reported, PF_NO_COMPOUND) + +#ifdef CONFIG_MEMORY_HOTPLUG +PAGEFLAG(VmemmapSelfHosted, vmemmap_self_hosted, PF_ANY) +#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 FOLIO_MAPPING_ANON bit set to distinguish it. See rmap.h. + * + * On an anonymous folio in a VM_MERGEABLE area, if CONFIG_KSM is enabled, + * the FOLIO_MAPPING_ANON_KSM bit may be set along with the FOLIO_MAPPING_ANON + * bit; and then folio->mapping points, not to an anon_vma, but to a private + * structure which KSM associates with that merged folio. See ksm.h. + * + * 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 FOLIO_MAPPING_ANON 0x1 +#define FOLIO_MAPPING_ANON_KSM 0x2 +#define FOLIO_MAPPING_KSM (FOLIO_MAPPING_ANON | FOLIO_MAPPING_ANON_KSM) +#define FOLIO_MAPPING_FLAGS (FOLIO_MAPPING_ANON | FOLIO_MAPPING_ANON_KSM) + +static __always_inline bool folio_test_anon(const struct folio *folio) +{ + return ((unsigned long)folio->mapping & FOLIO_MAPPING_ANON) != 0; +} + +static __always_inline bool folio_test_lazyfree(const struct folio *folio) +{ + return folio_test_anon(folio) && !folio_test_swapbacked(folio); +} + +static __always_inline bool PageAnonNotKsm(const struct page *page) +{ + unsigned long flags = (unsigned long)page_folio(page)->mapping; + + return (flags & FOLIO_MAPPING_FLAGS) == FOLIO_MAPPING_ANON; +} + +static __always_inline bool PageAnon(const struct page *page) +{ + return folio_test_anon(page_folio(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) +{ + return ((unsigned long)folio->mapping & FOLIO_MAPPING_FLAGS) == + FOLIO_MAPPING_KSM; +} +#else +FOLIO_TEST_FLAG_FALSE(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) +{ + return xor_unlock_is_negative_byte(mask, folio_flags(folio, 0)); +} + +/** + * 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) +{ + bool ret = test_bit(PG_uptodate, const_folio_flags(folio, 0)); + /* + * Must ensure that the data we read out of the folio is loaded + * _after_ we've loaded folio->flags to check the uptodate bit. + * We can skip the barrier if the folio is not uptodate, because + * we wouldn't be reading anything from it. + * + * See folio_mark_uptodate() for the other side of the story. + */ + if (ret) + smp_rmb(); + + return ret; +} + +static inline bool PageUptodate(const struct page *page) +{ + return folio_test_uptodate(page_folio(page)); +} + +static __always_inline void __folio_mark_uptodate(struct folio *folio) +{ + smp_wmb(); + __set_bit(PG_uptodate, folio_flags(folio, 0)); +} + +static __always_inline void folio_mark_uptodate(struct folio *folio) +{ + /* + * Memory barrier must be issued before setting the PG_uptodate bit, + * so that all previous stores issued in order to bring the folio + * uptodate are actually visible before folio_test_uptodate becomes true. + */ + smp_wmb(); + set_bit(PG_uptodate, folio_flags(folio, 0)); +} + +static __always_inline void __SetPageUptodate(struct page *page) +{ + __folio_mark_uptodate((struct folio *)page); +} + +static __always_inline void SetPageUptodate(struct page *page) +{ + folio_mark_uptodate((struct folio *)page); +} + +CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL) + +void __folio_start_writeback(struct folio *folio, bool keep_write); +void set_page_writeback(struct page *page); + +#define folio_start_writeback(folio) \ + __folio_start_writeback(folio, false) + +static __always_inline bool folio_test_head(const struct folio *folio) +{ + return test_bit(PG_head, const_folio_flags(folio, FOLIO_PF_ANY)); +} + +static __always_inline int PageHead(const struct page *page) +{ + PF_POISONED_CHECK(page); + return test_bit(PG_head, &page->flags.f); +} + +__SETPAGEFLAG(Head, head, PF_ANY) +__CLEARPAGEFLAG(Head, head, PF_ANY) +CLEARPAGEFLAG(Head, head, PF_ANY) + +/** + * 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) +{ + return folio_test_head(folio); +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +static inline void ClearPageCompound(struct page *page) +{ + BUG_ON(!PageHead(page)); + ClearPageHead(page); +} +FOLIO_FLAG(large_rmappable, FOLIO_SECOND_PAGE) +FOLIO_FLAG(partially_mapped, FOLIO_SECOND_PAGE) +#else +FOLIO_FLAG_FALSE(large_rmappable) +FOLIO_FLAG_FALSE(partially_mapped) +#endif + +#define PG_head_mask ((1UL << PG_head)) + +#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. + */ +FOLIO_FLAG(has_hwpoisoned, FOLIO_SECOND_PAGE) +#else +FOLIO_FLAG_FALSE(has_hwpoisoned) +#endif + +/* + * For pages that do not use mapcount, page_type may be used. + * The low 24 bits of pagetype may be used for your own purposes, as long + * as you are careful to not affect the top 8 bits. The low bits of + * pagetype will be overwritten when you clear the page_type from the page. + */ +enum pagetype { + /* 0x00-0x7f are positive numbers, ie mapcount */ + /* Reserve 0x80-0xef for mapcount overflow. */ + PGTY_buddy = 0xf0, + PGTY_offline = 0xf1, + PGTY_table = 0xf2, + PGTY_guard = 0xf3, + PGTY_hugetlb = 0xf4, + PGTY_slab = 0xf5, + PGTY_zsmalloc = 0xf6, + PGTY_unaccepted = 0xf7, + PGTY_large_kmalloc = 0xf8, + + PGTY_mapcount_underflow = 0xff +}; + +static inline bool page_type_has_type(int page_type) +{ + return page_type < (PGTY_mapcount_underflow << 24); +} + +/* This takes a mapcount which is one more than page->_mapcount */ +static inline bool page_mapcount_is_type(unsigned int mapcount) +{ + return page_type_has_type(mapcount - 1); +} + +static inline bool page_has_type(const struct page *page) +{ + return page_type_has_type(data_race(page->page_type)); +} + +#define FOLIO_TYPE_OPS(lname, fname) \ +static __always_inline bool folio_test_##fname(const struct folio *folio) \ +{ \ + return data_race(folio->page.page_type >> 24) == PGTY_##lname; \ +} \ +static __always_inline void __folio_set_##fname(struct folio *folio) \ +{ \ + if (folio_test_##fname(folio)) \ + return; \ + VM_BUG_ON_FOLIO(data_race(folio->page.page_type) != UINT_MAX, \ + folio); \ + folio->page.page_type = (unsigned int)PGTY_##lname << 24; \ +} \ +static __always_inline void __folio_clear_##fname(struct folio *folio) \ +{ \ + if (folio->page.page_type == UINT_MAX) \ + return; \ + VM_BUG_ON_FOLIO(!folio_test_##fname(folio), folio); \ + folio->page.page_type = UINT_MAX; \ +} + +#define PAGE_TYPE_OPS(uname, lname, fname) \ +FOLIO_TYPE_OPS(lname, fname) \ +static __always_inline int Page##uname(const struct page *page) \ +{ \ + return data_race(page->page_type >> 24) == PGTY_##lname; \ +} \ +static __always_inline void __SetPage##uname(struct page *page) \ +{ \ + if (Page##uname(page)) \ + return; \ + VM_BUG_ON_PAGE(data_race(page->page_type) != UINT_MAX, page); \ + page->page_type = (unsigned int)PGTY_##lname << 24; \ +} \ +static __always_inline void __ClearPage##uname(struct page *page) \ +{ \ + if (page->page_type == UINT_MAX) \ + return; \ + VM_BUG_ON_PAGE(!Page##uname(page), page); \ + page->page_type = UINT_MAX; \ +} + +/* + * PageBuddy() indicates that the page is free and in the buddy system + * (see mm/page_alloc.c). + */ +PAGE_TYPE_OPS(Buddy, buddy, buddy) + +/* + * 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(Offline, offline, offline) + +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(Table, table, pgtable) + +/* + * Marks guardpages used with debug_pagealloc. + */ +PAGE_TYPE_OPS(Guard, guard, guard) + +PAGE_TYPE_OPS(Slab, slab, slab) + +#ifdef CONFIG_HUGETLB_PAGE +FOLIO_TYPE_OPS(hugetlb, hugetlb) +#else +FOLIO_TEST_FLAG_FALSE(hugetlb) +#endif + +PAGE_TYPE_OPS(Zsmalloc, zsmalloc, zsmalloc) + +/* + * Mark pages that has to be accepted before touched for the first time. + * + * Serialized with zone lock. + */ +PAGE_TYPE_OPS(Unaccepted, unaccepted, unaccepted) +PAGE_TYPE_OPS(LargeKmalloc, large_kmalloc, large_kmalloc) + +/** + * 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) +{ + return folio_test_hugetlb(page_folio(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) +{ + const struct folio *folio; + + if (PageHWPoison(page)) + return true; + folio = page_folio(page); + return folio_test_hugetlb(folio) && PageHWPoison(&folio->page); +} + +static inline bool folio_contain_hwpoisoned_page(struct folio *folio) +{ + return folio_test_hwpoison(folio) || + (folio_test_large(folio) && folio_test_has_hwpoisoned(folio)); +} + +bool is_free_buddy_page(const struct page *page); + +#ifdef CONFIG_MIGRATION +/* + * This page is migratable through movable_ops (for selected typed pages + * only). + * + * Page migration of such pages might fail, for example, if the page is + * already isolated by somebody else, or if the page is about to get freed. + * + * While a subsystem might set selected typed pages that support page migration + * as being movable through movable_ops, it must never clear this flag. + * + * This flag is only cleared when the page is freed back to the buddy. + * + * Only selected page types support this flag (see page_movable_ops()) and + * the flag might be used in other context for other pages. Always use + * page_has_movable_ops() instead. + */ +TESTPAGEFLAG(MovableOps, movable_ops, PF_NO_TAIL); +SETPAGEFLAG(MovableOps, movable_ops, PF_NO_TAIL); +/* + * A movable_ops page has this flag set while it is isolated for migration. + * This flag primarily protects against concurrent migration attempts. + * + * Once migration ended (success or failure), the flag is cleared. The + * flag is managed by the migration core. + */ +PAGEFLAG(MovableOpsIsolated, movable_ops_isolated, PF_NO_TAIL); +#else /* !CONFIG_MIGRATION */ +TESTPAGEFLAG_FALSE(MovableOps, movable_ops); +SETPAGEFLAG_NOOP(MovableOps, movable_ops); +PAGEFLAG_FALSE(MovableOpsIsolated, movable_ops_isolated); +#endif /* CONFIG_MIGRATION */ + +/** + * page_has_movable_ops - test for a movable_ops page + * @page: The page to test. + * + * Test whether this is a movable_ops page. Such pages will stay that + * way until freed. + * + * Returns true if this is a movable_ops page, otherwise false. + */ +static inline bool page_has_movable_ops(const struct page *page) +{ + return PageMovableOps(page) && + (PageOffline(page) || PageZsmalloc(page)); +} + +static __always_inline int PageAnonExclusive(const struct page *page) +{ + VM_BUG_ON_PGFLAGS(!PageAnon(page), page); + /* + * HugeTLB stores this information on the head page; THP keeps it per + * page + */ + if (PageHuge(page)) + page = compound_head(page); + return test_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags.f); +} + +static __always_inline void SetPageAnonExclusive(struct page *page) +{ + VM_BUG_ON_PGFLAGS(!PageAnonNotKsm(page), page); + VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page); + set_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags.f); +} + +static __always_inline void ClearPageAnonExclusive(struct page *page) +{ + VM_BUG_ON_PGFLAGS(!PageAnonNotKsm(page), page); + VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page); + clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags.f); +} + +static __always_inline void __ClearPageAnonExclusive(struct page *page) +{ + VM_BUG_ON_PGFLAGS(!PageAnon(page), page); + VM_BUG_ON_PGFLAGS(PageHuge(page) && !PageHead(page), page); + __clear_bit(PG_anon_exclusive, &PF_ANY(page, 1)->flags.f); +} + +#ifdef CONFIG_MMU +#define __PG_MLOCKED (1UL << PG_mlocked) +#else +#define __PG_MLOCKED 0 +#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 \ + (1UL << PG_lru | 1UL << PG_locked | \ + 1UL << PG_private | 1UL << PG_private_2 | \ + 1UL << PG_writeback | 1UL << PG_reserved | \ + 1UL << PG_active | \ + 1UL << PG_unevictable | __PG_MLOCKED | LRU_GEN_MASK) + +/* + * 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 \ + ((PAGEFLAGS_MASK & ~__PG_HWPOISON) | LRU_GEN_MASK | LRU_REFS_MASK) + +/* + * 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 \ + (0xffUL /* order */ | 1UL << PG_has_hwpoisoned | \ + 1UL << PG_large_rmappable | 1UL << PG_partially_mapped) + +#define PAGE_FLAGS_PRIVATE \ + (1UL << PG_private | 1UL << PG_private_2) +/** + * folio_has_private - Determine if folio has private stuff + * @folio: The folio to be checked + * + * Determine if a folio has private stuff, indicating that release routines + * should be invoked upon it. + */ +static inline int folio_has_private(const struct folio *folio) +{ + return !!(folio->flags.f & PAGE_FLAGS_PRIVATE); +} + +#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 */ |