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Diffstat (limited to 'include/linux/page-flags.h')
| -rw-r--r-- | include/linux/page-flags.h | 487 |
1 files changed, 487 insertions, 0 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h new file mode 100644 index 00000000..6081493d --- /dev/null +++ b/include/linux/page-flags.h @@ -0,0 +1,487 @@ +/* + * Macros for manipulating and testing page->flags + */ + +#ifndef PAGE_FLAGS_H +#define PAGE_FLAGS_H + +#include <linux/types.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, which can never be swapped out. Some + * of them might not even exist (eg empty_bad_page)... + * + * 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_uptodate tells whether the page's contents is valid. When a read + * completes, the page becomes uptodate, unless a disk I/O error happened. + * + * 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_highmem pages are not permanently mapped into the kernel virtual address + * space, they need to be kmapped separately for doing IO on the pages. The + * struct page (these bits with information) are always mapped into kernel + * address space... + * + * 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 *_dontuse flags. Use the macros. Otherwise you'll break + * locked- and dirty-page accounting. + * + * 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_error, + PG_referenced, + PG_uptodate, + PG_dirty, + PG_lru, + PG_active, + PG_slab, + PG_owner_priv_1, /* 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_writeback, /* Page is under writeback */ +#ifdef CONFIG_PAGEFLAGS_EXTENDED + PG_head, /* A head page */ + PG_tail, /* A tail page */ +#else + PG_compound, /* A compound page */ +#endif + PG_swapcache, /* Swap page: swp_entry_t in private */ + PG_mappedtodisk, /* Has blocks allocated on-disk */ + PG_reclaim, /* To be reclaimed asap */ + PG_swapbacked, /* Page is backed by RAM/swap */ + PG_unevictable, /* Page is "unevictable" */ +#ifdef CONFIG_MMU + PG_mlocked, /* Page is vma mlocked */ +#endif +#ifdef CONFIG_ARCH_USES_PG_UNCACHED + PG_uncached, /* Page has been mapped as uncached */ +#endif +#ifdef CONFIG_MEMORY_FAILURE + PG_hwpoison, /* hardware poisoned page. Don't touch */ +#endif +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + PG_compound_lock, +#endif + __NR_PAGEFLAGS, + + /* Filesystems */ + PG_checked = PG_owner_priv_1, + + /* 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 */ + PG_pinned = PG_owner_priv_1, + PG_savepinned = PG_dirty, + + /* SLOB */ + PG_slob_free = PG_private, + + /* SLUB */ + PG_slub_frozen = PG_active, +}; + +#ifndef __GENERATING_BOUNDS_H + +/* + * Macros to create function definitions for page flags + */ +#define TESTPAGEFLAG(uname, lname) \ +static inline int Page##uname(struct page *page) \ + { return test_bit(PG_##lname, &page->flags); } + +#define SETPAGEFLAG(uname, lname) \ +static inline void SetPage##uname(struct page *page) \ + { set_bit(PG_##lname, &page->flags); } + +#define CLEARPAGEFLAG(uname, lname) \ +static inline void ClearPage##uname(struct page *page) \ + { clear_bit(PG_##lname, &page->flags); } + +#define __SETPAGEFLAG(uname, lname) \ +static inline void __SetPage##uname(struct page *page) \ + { __set_bit(PG_##lname, &page->flags); } + +#define __CLEARPAGEFLAG(uname, lname) \ +static inline void __ClearPage##uname(struct page *page) \ + { __clear_bit(PG_##lname, &page->flags); } + +#define TESTSETFLAG(uname, lname) \ +static inline int TestSetPage##uname(struct page *page) \ + { return test_and_set_bit(PG_##lname, &page->flags); } + +#define TESTCLEARFLAG(uname, lname) \ +static inline int TestClearPage##uname(struct page *page) \ + { return test_and_clear_bit(PG_##lname, &page->flags); } + +#define __TESTCLEARFLAG(uname, lname) \ +static inline int __TestClearPage##uname(struct page *page) \ + { return __test_and_clear_bit(PG_##lname, &page->flags); } + +#define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \ + SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname) + +#define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \ + __SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname) + +#define PAGEFLAG_FALSE(uname) \ +static inline int Page##uname(struct page *page) \ + { return 0; } + +#define TESTSCFLAG(uname, lname) \ + TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname) + +#define SETPAGEFLAG_NOOP(uname) \ +static inline void SetPage##uname(struct page *page) { } + +#define CLEARPAGEFLAG_NOOP(uname) \ +static inline void ClearPage##uname(struct page *page) { } + +#define __CLEARPAGEFLAG_NOOP(uname) \ +static inline void __ClearPage##uname(struct page *page) { } + +#define TESTCLEARFLAG_FALSE(uname) \ +static inline int TestClearPage##uname(struct page *page) { return 0; } + +#define __TESTCLEARFLAG_FALSE(uname) \ +static inline int __TestClearPage##uname(struct page *page) { return 0; } + +struct page; /* forward declaration */ + +TESTPAGEFLAG(Locked, locked) +PAGEFLAG(Error, error) TESTCLEARFLAG(Error, error) +PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced) +PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty) +PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru) +PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active) + TESTCLEARFLAG(Active, active) +__PAGEFLAG(Slab, slab) +PAGEFLAG(Checked, checked) /* Used by some filesystems */ +PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen */ +PAGEFLAG(SavePinned, savepinned); /* Xen */ +PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved) +PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked) + +__PAGEFLAG(SlobFree, slob_free) + +__PAGEFLAG(SlubFrozen, slub_frozen) + +/* + * 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 releasepage() and co to be invoked + */ +PAGEFLAG(Private, private) __SETPAGEFLAG(Private, private) + __CLEARPAGEFLAG(Private, private) +PAGEFLAG(Private2, private_2) TESTSCFLAG(Private2, private_2) +PAGEFLAG(OwnerPriv1, owner_priv_1) TESTCLEARFLAG(OwnerPriv1, owner_priv_1) + +/* + * Only test-and-set exist for PG_writeback. The unconditional operators are + * risky: they bypass page accounting. + */ +TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback) +PAGEFLAG(MappedToDisk, mappedtodisk) + +/* PG_readahead is only used for file reads; PG_reclaim is only for writes */ +PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim) +PAGEFLAG(Readahead, reclaim) /* Reminder to do async read-ahead */ + +#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(page_zone(__p)) +#else +PAGEFLAG_FALSE(HighMem) +#endif + +#ifdef CONFIG_SWAP +PAGEFLAG(SwapCache, swapcache) +#else +PAGEFLAG_FALSE(SwapCache) + SETPAGEFLAG_NOOP(SwapCache) CLEARPAGEFLAG_NOOP(SwapCache) +#endif + +PAGEFLAG(Unevictable, unevictable) __CLEARPAGEFLAG(Unevictable, unevictable) + TESTCLEARFLAG(Unevictable, unevictable) + +#ifdef CONFIG_MMU +PAGEFLAG(Mlocked, mlocked) __CLEARPAGEFLAG(Mlocked, mlocked) + TESTSCFLAG(Mlocked, mlocked) __TESTCLEARFLAG(Mlocked, mlocked) +#else +PAGEFLAG_FALSE(Mlocked) SETPAGEFLAG_NOOP(Mlocked) + TESTCLEARFLAG_FALSE(Mlocked) __TESTCLEARFLAG_FALSE(Mlocked) +#endif + +#ifdef CONFIG_ARCH_USES_PG_UNCACHED +PAGEFLAG(Uncached, uncached) +#else +PAGEFLAG_FALSE(Uncached) +#endif + +#ifdef CONFIG_MEMORY_FAILURE +PAGEFLAG(HWPoison, hwpoison) +TESTSCFLAG(HWPoison, hwpoison) +#define __PG_HWPOISON (1UL << PG_hwpoison) +#else +PAGEFLAG_FALSE(HWPoison) +#define __PG_HWPOISON 0 +#endif + +u64 stable_page_flags(struct page *page); + +static inline int PageUptodate(struct page *page) +{ + int ret = test_bit(PG_uptodate, &(page)->flags); + + /* + * Must ensure that the data we read out of the page is loaded + * _after_ we've loaded page->flags to check for PageUptodate. + * We can skip the barrier if the page is not uptodate, because + * we wouldn't be reading anything from it. + * + * See SetPageUptodate() for the other side of the story. + */ + if (ret) + smp_rmb(); + + return ret; +} + +static inline void __SetPageUptodate(struct page *page) +{ + smp_wmb(); + __set_bit(PG_uptodate, &(page)->flags); +} + +static inline void SetPageUptodate(struct page *page) +{ +#ifdef CONFIG_S390 + if (!test_and_set_bit(PG_uptodate, &page->flags)) + page_set_storage_key(page_to_phys(page), PAGE_DEFAULT_KEY, 0); +#else + /* + * Memory barrier must be issued before setting the PG_uptodate bit, + * so that all previous stores issued in order to bring the page + * uptodate are actually visible before PageUptodate becomes true. + * + * s390 doesn't need an explicit smp_wmb here because the test and + * set bit already provides full barriers. + */ + smp_wmb(); + set_bit(PG_uptodate, &(page)->flags); +#endif +} + +CLEARPAGEFLAG(Uptodate, uptodate) + +extern void cancel_dirty_page(struct page *page, unsigned int account_size); + +int test_clear_page_writeback(struct page *page); +int test_set_page_writeback(struct page *page); + +static inline void set_page_writeback(struct page *page) +{ + test_set_page_writeback(page); +} + +#ifdef CONFIG_PAGEFLAGS_EXTENDED +/* + * System with lots of page flags available. This allows separate + * flags for PageHead() and PageTail() checks of compound pages so that bit + * tests can be used in performance sensitive paths. PageCompound is + * generally not used in hot code paths. + */ +__PAGEFLAG(Head, head) CLEARPAGEFLAG(Head, head) +__PAGEFLAG(Tail, tail) + +static inline int PageCompound(struct page *page) +{ + return page->flags & ((1L << PG_head) | (1L << PG_tail)); + +} +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +static inline void ClearPageCompound(struct page *page) +{ + BUG_ON(!PageHead(page)); + ClearPageHead(page); +} +#endif +#else +/* + * Reduce page flag use as much as possible by overlapping + * compound page flags with the flags used for page cache pages. Possible + * because PageCompound is always set for compound pages and not for + * pages on the LRU and/or pagecache. + */ +TESTPAGEFLAG(Compound, compound) +__PAGEFLAG(Head, compound) + +/* + * PG_reclaim is used in combination with PG_compound to mark the + * head and tail of a compound page. This saves one page flag + * but makes it impossible to use compound pages for the page cache. + * The PG_reclaim bit would have to be used for reclaim or readahead + * if compound pages enter the page cache. + * + * PG_compound & PG_reclaim => Tail page + * PG_compound & ~PG_reclaim => Head page + */ +#define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim)) + +static inline int PageTail(struct page *page) +{ + return ((page->flags & PG_head_tail_mask) == PG_head_tail_mask); +} + +static inline void __SetPageTail(struct page *page) +{ + page->flags |= PG_head_tail_mask; +} + +static inline void __ClearPageTail(struct page *page) +{ + page->flags &= ~PG_head_tail_mask; +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +static inline void ClearPageCompound(struct page *page) +{ + BUG_ON((page->flags & PG_head_tail_mask) != (1 << PG_compound)); + clear_bit(PG_compound, &page->flags); +} +#endif + +#endif /* !PAGEFLAGS_EXTENDED */ + +#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(struct page *page) +{ + VM_BUG_ON(PageTail(page)); + return PageHead(page); +} + +static inline int PageTransCompound(struct page *page) +{ + return PageCompound(page); +} + +#else + +static inline int PageTransHuge(struct page *page) +{ + return 0; +} + +static inline int PageTransCompound(struct page *page) +{ + return 0; +} +#endif + +#ifdef CONFIG_MMU +#define __PG_MLOCKED (1 << PG_mlocked) +#else +#define __PG_MLOCKED 0 +#endif + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#define __PG_COMPOUND_LOCK (1 << PG_compound_lock) +#else +#define __PG_COMPOUND_LOCK 0 +#endif + +/* + * Flags checked when a page is freed. Pages being freed should not have + * these flags set. It they are, there is a problem. + */ +#define PAGE_FLAGS_CHECK_AT_FREE \ + (1 << PG_lru | 1 << PG_locked | \ + 1 << PG_private | 1 << PG_private_2 | \ + 1 << PG_writeback | 1 << PG_reserved | \ + 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active | \ + 1 << PG_unevictable | __PG_MLOCKED | __PG_HWPOISON | \ + __PG_COMPOUND_LOCK) + +/* + * Flags checked when a page is prepped for return by the page allocator. + * Pages being prepped should not have any flags set. It they are set, + * there has been a kernel bug or struct page corruption. + */ +#define PAGE_FLAGS_CHECK_AT_PREP ((1 << NR_PAGEFLAGS) - 1) + +#define PAGE_FLAGS_PRIVATE \ + (1 << PG_private | 1 << PG_private_2) +/** + * 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(struct page *page) +{ + return !!(page->flags & PAGE_FLAGS_PRIVATE); +} + +#endif /* !__GENERATING_BOUNDS_H */ + +#endif /* PAGE_FLAGS_H */ |