include/linux/page-flags.h - kernel/msm-4.19 - Gitiles

 /*
  * 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, 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 */
 	/* 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,

 	/* SLOB */
 	PG_slob_free = PG_private,
 };

 #ifndef __GENERATING_BOUNDS_H

 /*
  * Macros to create function definitions for page flags
  */
 #define TESTPAGEFLAG(uname, lname)					\
 static inline int Page##uname(const 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 TESTSCFLAG(uname, lname)					\
 	TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)

 #define TESTPAGEFLAG_FALSE(uname)					\
 static inline int Page##uname(const struct page *page) { return 0; }

 #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 TESTSETFLAG_FALSE(uname)					\
 static inline int TestSetPage##uname(struct page *page) { return 0; }

 #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; }

 #define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname)			\
 	SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)

 #define TESTSCFLAG_FALSE(uname)						\
 	TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)

 struct page;	/* forward declaration */

 TESTPAGEFLAG(Locked, locked)
 PAGEFLAG(Error, error) TESTCLEARFLAG(Error, error)
 PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
 	__SETPAGEFLAG(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(Foreign, foreign);				/* Xen */
 PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
 PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked)
 	__SETPAGEFLAG(SwapBacked, swapbacked)

 __PAGEFLAG(SlobFree, slob_free)

 /*
  * 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 reads; PG_reclaim is only for writes */
 PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim)
 PAGEFLAG(Readahead, reclaim) TESTCLEARFLAG(Readahead, reclaim)

 #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)
 #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) __CLEARPAGEFLAG_NOOP(Mlocked)
 	TESTSCFLAG_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

 /*
  * On an anonymous page mapped into a user virtual memory area,
  * page->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_KSM bit may be set along with the PAGE_MAPPING_ANON bit;
  * and then page->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 currently never used.
  *
  * Please note that, confusingly, "page_mapping" refers to the inode
  * address_space which maps the page from disk; whereas "page_mapped"
  * refers to user virtual address space into which the page is mapped.
  */
 #define PAGE_MAPPING_ANON	1
 #define PAGE_MAPPING_KSM	2
 #define PAGE_MAPPING_FLAGS	(PAGE_MAPPING_ANON | PAGE_MAPPING_KSM)

 static inline int PageAnon(struct page *page)
 {
 	return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
 }

 #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 inline int PageKsm(struct page *page)
 {
 	return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
 				(PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
 }
 #else
 TESTPAGEFLAG_FALSE(Ksm)
 #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)
 {
 	/*
 	 * 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.
 	 */
 	smp_wmb();
 	set_bit(PG_uptodate, &(page)->flags);
 }

 CLEARPAGEFLAG(Uptodate, uptodate)

 int test_clear_page_writeback(struct page *page);
 int __test_set_page_writeback(struct page *page, bool keep_write);

 #define test_set_page_writeback(page)			\
 	__test_set_page_writeback(page, false)
 #define test_set_page_writeback_keepwrite(page)	\
 	__test_set_page_writeback(page, true)

 static inline void set_page_writeback(struct page *page)
 {
 	test_set_page_writeback(page);
 }

 static inline void set_page_writeback_keepwrite(struct page *page)
 {
 	test_set_page_writeback_keepwrite(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 except arch/powerpc/mm/init_64.c
  * and arch/powerpc/kvm/book3s_64_vio_hv.c which use it to detect huge pages
  * and avoid handling those in real mode.
  */
 __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

 #define PG_head_mask ((1L << PG_head))

 #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)
 __SETPAGEFLAG(Head, compound)  __CLEARPAGEFLAG(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_mask ((1L << PG_compound))
 #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))

 static inline int PageHead(struct page *page)
 {
 	return ((page->flags & PG_head_tail_mask) == PG_head_mask);
 }

 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_HUGETLB_PAGE
 int PageHuge(struct page *page);
 int PageHeadHuge(struct page *page);
 bool page_huge_active(struct page *page);
 #else
 TESTPAGEFLAG_FALSE(Huge)
 TESTPAGEFLAG_FALSE(HeadHuge)

 static inline bool page_huge_active(struct page *page)
 {
 	return 0;
 }
 #endif


 #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_PAGE(PageTail(page), page);
 	return PageHead(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(struct page *page)
 {
 	return PageCompound(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(struct page *page)
 {
 	return PageTail(page);
 }

 #else

 static inline int PageTransHuge(struct page *page)
 {
 	return 0;
 }

 static inline int PageTransCompound(struct page *page)
 {
 	return 0;
 }

 static inline int PageTransTail(struct page *page)
 {
 	return 0;
 }
 #endif

 /*
  * PageBuddy() indicate that the page is free and in the buddy system
  * (see mm/page_alloc.c).
  *
  * PAGE_BUDDY_MAPCOUNT_VALUE must be <= -2 but better not too close to
  * -2 so that an underflow of the page_mapcount() won't be mistaken
  * for a genuine PAGE_BUDDY_MAPCOUNT_VALUE. -128 can be created very
  * efficiently by most CPU architectures.
  */
 #define PAGE_BUDDY_MAPCOUNT_VALUE (-128)

 static inline int PageBuddy(struct page *page)
 {
 	return atomic_read(&page->_mapcount) == PAGE_BUDDY_MAPCOUNT_VALUE;
 }

 static inline void __SetPageBuddy(struct page *page)
 {
 	VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
 	atomic_set(&page->_mapcount, PAGE_BUDDY_MAPCOUNT_VALUE);
 }

 static inline void __ClearPageBuddy(struct page *page)
 {
 	VM_BUG_ON_PAGE(!PageBuddy(page), page);
 	atomic_set(&page->_mapcount, -1);
 }

 #define PAGE_BALLOON_MAPCOUNT_VALUE (-256)

 static inline int PageBalloon(struct page *page)
 {
 	return atomic_read(&page->_mapcount) == PAGE_BALLOON_MAPCOUNT_VALUE;
 }

 static inline void __SetPageBalloon(struct page *page)
 {
 	VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
 	atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE);
 }

 static inline void __ClearPageBalloon(struct page *page)
 {
 	VM_BUG_ON_PAGE(!PageBalloon(page), page);
 	atomic_set(&page->_mapcount, -1);
 }

 /*
  * If network-based swap is enabled, sl*b must keep track of whether pages
  * were allocated from pfmemalloc reserves.
  */
 static inline int PageSlabPfmemalloc(struct page *page)
 {
 	VM_BUG_ON_PAGE(!PageSlab(page), page);
 	return PageActive(page);
 }

 static inline void SetPageSlabPfmemalloc(struct page *page)
 {
 	VM_BUG_ON_PAGE(!PageSlab(page), page);
 	SetPageActive(page);
 }

 static inline void __ClearPageSlabPfmemalloc(struct page *page)
 {
 	VM_BUG_ON_PAGE(!PageSlab(page), page);
 	__ClearPageActive(page);
 }

 static inline void ClearPageSlabPfmemalloc(struct page *page)
 {
 	VM_BUG_ON_PAGE(!PageSlab(page), page);
 	ClearPageActive(page);
 }

 #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_COMPOUND_LOCK)

 /*
  * Flags checked when a page is prepped for return by the page allocator.
  * Pages being prepped should not have these flags set.  It 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	\
 	(((1 << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)

 #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 */
	/*
	* 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, 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 */
	/* 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,

	/* SLOB */
	PG_slob_free = PG_private,
	};

	#ifndef __GENERATING_BOUNDS_H

	/*
	* Macros to create function definitions for page flags
	*/
	#define TESTPAGEFLAG(uname, lname) \
	static inline int Page##uname(const 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 TESTSCFLAG(uname, lname) \
	TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)

	#define TESTPAGEFLAG_FALSE(uname) \
	static inline int Page##uname(const struct page *page) { return 0; }

	#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 TESTSETFLAG_FALSE(uname) \
	static inline int TestSetPage##uname(struct page *page) { return 0; }

	#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; }

	#define PAGEFLAG_FALSE(uname) TESTPAGEFLAG_FALSE(uname) \
	SETPAGEFLAG_NOOP(uname) CLEARPAGEFLAG_NOOP(uname)

	#define TESTSCFLAG_FALSE(uname) \
	TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)

	struct page; /* forward declaration */

	TESTPAGEFLAG(Locked, locked)
	PAGEFLAG(Error, error) TESTCLEARFLAG(Error, error)
	PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
	__SETPAGEFLAG(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(Foreign, foreign); /* Xen */
	PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
	PAGEFLAG(SwapBacked, swapbacked) __CLEARPAGEFLAG(SwapBacked, swapbacked)
	__SETPAGEFLAG(SwapBacked, swapbacked)

	__PAGEFLAG(SlobFree, slob_free)

	/*
	* 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 reads; PG_reclaim is only for writes */
	PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim)
	PAGEFLAG(Readahead, reclaim) TESTCLEARFLAG(Readahead, reclaim)

	#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)
	#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) __CLEARPAGEFLAG_NOOP(Mlocked)
	TESTSCFLAG_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

	/*
	* On an anonymous page mapped into a user virtual memory area,
	* page->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_KSM bit may be set along with the PAGE_MAPPING_ANON bit;
	* and then page->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 currently never used.
	*
	* Please note that, confusingly, "page_mapping" refers to the inode
	* address_space which maps the page from disk; whereas "page_mapped"
	* refers to user virtual address space into which the page is mapped.
	*/
	#define PAGE_MAPPING_ANON 1
	#define PAGE_MAPPING_KSM 2
	#define PAGE_MAPPING_FLAGS (PAGE_MAPPING_ANON \| PAGE_MAPPING_KSM)

	static inline int PageAnon(struct page *page)
	{
	return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
	}

	#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 inline int PageKsm(struct page *page)
	{
	return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
	(PAGE_MAPPING_ANON \| PAGE_MAPPING_KSM);
	}
	#else
	TESTPAGEFLAG_FALSE(Ksm)
	#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)
	{
	/*
	* 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.
	*/
	smp_wmb();
	set_bit(PG_uptodate, &(page)->flags);
	}

	CLEARPAGEFLAG(Uptodate, uptodate)

	int test_clear_page_writeback(struct page *page);
	int __test_set_page_writeback(struct page *page, bool keep_write);

	#define test_set_page_writeback(page) \
	__test_set_page_writeback(page, false)
	#define test_set_page_writeback_keepwrite(page) \
	__test_set_page_writeback(page, true)

	static inline void set_page_writeback(struct page *page)
	{
	test_set_page_writeback(page);
	}

	static inline void set_page_writeback_keepwrite(struct page *page)
	{
	test_set_page_writeback_keepwrite(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 except arch/powerpc/mm/init_64.c
	* and arch/powerpc/kvm/book3s_64_vio_hv.c which use it to detect huge pages
	* and avoid handling those in real mode.
	*/
	__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

	#define PG_head_mask ((1L << PG_head))

	#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)
	__SETPAGEFLAG(Head, compound) __CLEARPAGEFLAG(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_mask ((1L << PG_compound))
	#define PG_head_tail_mask ((1L << PG_compound) \| (1L << PG_reclaim))

	static inline int PageHead(struct page *page)
	{
	return ((page->flags & PG_head_tail_mask) == PG_head_mask);
	}

	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_HUGETLB_PAGE
	int PageHuge(struct page *page);
	int PageHeadHuge(struct page *page);
	bool page_huge_active(struct page *page);
	#else
	TESTPAGEFLAG_FALSE(Huge)
	TESTPAGEFLAG_FALSE(HeadHuge)

	static inline bool page_huge_active(struct page *page)
	{
	return 0;
	}
	#endif


	#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_PAGE(PageTail(page), page);
	return PageHead(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(struct page *page)
	{
	return PageCompound(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(struct page *page)
	{
	return PageTail(page);
	}

	#else

	static inline int PageTransHuge(struct page *page)
	{
	return 0;
	}

	static inline int PageTransCompound(struct page *page)
	{
	return 0;
	}

	static inline int PageTransTail(struct page *page)
	{
	return 0;
	}
	#endif

	/*
	* PageBuddy() indicate that the page is free and in the buddy system
	* (see mm/page_alloc.c).
	*
	* PAGE_BUDDY_MAPCOUNT_VALUE must be <= -2 but better not too close to
	* -2 so that an underflow of the page_mapcount() won't be mistaken
	* for a genuine PAGE_BUDDY_MAPCOUNT_VALUE. -128 can be created very
	* efficiently by most CPU architectures.
	*/
	#define PAGE_BUDDY_MAPCOUNT_VALUE (-128)

	static inline int PageBuddy(struct page *page)
	{
	return atomic_read(&page->_mapcount) == PAGE_BUDDY_MAPCOUNT_VALUE;
	}

	static inline void __SetPageBuddy(struct page *page)
	{
	VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
	atomic_set(&page->_mapcount, PAGE_BUDDY_MAPCOUNT_VALUE);
	}

	static inline void __ClearPageBuddy(struct page *page)
	{
	VM_BUG_ON_PAGE(!PageBuddy(page), page);
	atomic_set(&page->_mapcount, -1);
	}

	#define PAGE_BALLOON_MAPCOUNT_VALUE (-256)

	static inline int PageBalloon(struct page *page)
	{
	return atomic_read(&page->_mapcount) == PAGE_BALLOON_MAPCOUNT_VALUE;
	}

	static inline void __SetPageBalloon(struct page *page)
	{
	VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
	atomic_set(&page->_mapcount, PAGE_BALLOON_MAPCOUNT_VALUE);
	}

	static inline void __ClearPageBalloon(struct page *page)
	{
	VM_BUG_ON_PAGE(!PageBalloon(page), page);
	atomic_set(&page->_mapcount, -1);
	}

	/*
	* If network-based swap is enabled, sl*b must keep track of whether pages
	* were allocated from pfmemalloc reserves.
	*/
	static inline int PageSlabPfmemalloc(struct page *page)
	{
	VM_BUG_ON_PAGE(!PageSlab(page), page);
	return PageActive(page);
	}

	static inline void SetPageSlabPfmemalloc(struct page *page)
	{
	VM_BUG_ON_PAGE(!PageSlab(page), page);
	SetPageActive(page);
	}

	static inline void __ClearPageSlabPfmemalloc(struct page *page)
	{
	VM_BUG_ON_PAGE(!PageSlab(page), page);
	__ClearPageActive(page);
	}

	static inline void ClearPageSlabPfmemalloc(struct page *page)
	{
	VM_BUG_ON_PAGE(!PageSlab(page), page);
	ClearPageActive(page);
	}

	#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_COMPOUND_LOCK)

	/*
	* Flags checked when a page is prepped for return by the page allocator.
	* Pages being prepped should not have these flags set. It 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 \
	(((1 << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)

	#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 */