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/* 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>
#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 not added to the page allocator when onlining a section because
* they were excluded via the online_page_callback() or because they are
* PG_hwpoison.
* - 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).
* - Pages part of an offline section (struct pages of offline sections should
* not be trusted as they will be initialized when first onlined).
* - 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_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_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
* The fields area is reserved for fields mapping zone, node (for NUMA) and
* SPARSEMEM section (for variants of SPARSEMEM that require section ids like
enum pageflags {
PG_locked, /* Page is locked. Don't touch. */
PG_waiters, /* Page has waiters, check its waitqueue. Must be bit #7 and in the same byte as "PG_locked" */
PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
PG_private, /* If pagecache, has fs-private data */
PG_private_2, /* If pagecache, has fs aux data */
PG_writeback, /* Page is under writeback */
PG_head, /* A head page */
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" */
PG_mlocked, /* Page is vma mlocked */
PG_uncached, /* Page has been mapped as uncached */
PG_hwpoison, /* hardware poisoned page. Don't touch */
#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
#ifdef CONFIG_64BIT
/* Filesystems */
PG_checked = PG_owner_priv_1,
/* SwapBacked */
PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */
/* 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,
/* SLOB */
PG_slob_free = PG_private,
/* Compound pages. Stored in first tail page's flags */
PG_double_map = PG_workingset,
/* non-lru isolated movable page */
PG_isolated = PG_reclaim,
/* Only valid for buddy pages. Used to track pages that are reported */
PG_reported = PG_uptodate,
struct page; /* forward declaration */
static inline struct page *compound_head(struct page *page)
unsigned long head = READ_ONCE(page->compound_head);
if (unlikely(head & 1))
return (struct page *) (head - 1);
return page;
static __always_inline int PageTail(struct page *page)
return READ_ONCE(page->compound_head) & 1;
static __always_inline int PageCompound(struct page *page)
return test_bit(PG_head, &page->flags) || PageTail(page);
static inline int PagePoisoned(const struct page *page)
return page->flags == PAGE_POISON_PATTERN;
void page_init_poison(struct page *page, size_t size);
static inline void page_init_poison(struct page *page, size_t size)
* Page flags policies wrt compound pages
* check if this struct page poisoned/uninitialized
* the page flag is relevant for small, head and tail pages.
* for compound page all operations related to the page flag applied to
* head page.
* for compound page, callers only ever operate on the head page.
* modifications of the page flag must be done on small or head pages,
* checks can be done on tail pages too.
* the page flag is not relevant for compound pages.
* 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_ONLY_HEAD(page, enforce) ({ \
VM_BUG_ON_PGFLAGS(PageTail(page), 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); \
#define PF_SECOND(page, enforce) ({ \
VM_BUG_ON_PGFLAGS(!PageHead(page), page); \
PF_POISONED_CHECK(&page[1]); })
* Macros to create function definitions for page flags
#define TESTPAGEFLAG(uname, lname, policy) \
static __always_inline int Page##uname(struct page *page) \
{ return test_bit(PG_##lname, &policy(page, 0)->flags); }
#define SETPAGEFLAG(uname, lname, policy) \
static __always_inline void SetPage##uname(struct page *page) \
{ set_bit(PG_##lname, &policy(page, 1)->flags); }
#define CLEARPAGEFLAG(uname, lname, policy) \
static __always_inline void ClearPage##uname(struct page *page) \
{ clear_bit(PG_##lname, &policy(page, 1)->flags); }
#define __SETPAGEFLAG(uname, lname, policy) \
static __always_inline void __SetPage##uname(struct page *page) \
{ __set_bit(PG_##lname, &policy(page, 1)->flags); }
#define __CLEARPAGEFLAG(uname, lname, policy) \
static __always_inline void __ClearPage##uname(struct page *page) \
{ __clear_bit(PG_##lname, &policy(page, 1)->flags); }
#define TESTSETFLAG(uname, lname, policy) \
static __always_inline int TestSetPage##uname(struct page *page) \
{ return test_and_set_bit(PG_##lname, &policy(page, 1)->flags); }
#define TESTCLEARFLAG(uname, lname, policy) \
static __always_inline int TestClearPage##uname(struct page *page) \
{ return test_and_clear_bit(PG_##lname, &policy(page, 1)->flags); }
#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 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 TESTSCFLAG_FALSE(uname) \
__PAGEFLAG(Locked, locked, PF_NO_TAIL)
PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
PAGEFLAG(Referenced, referenced, PF_HEAD)
TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
__SETPAGEFLAG(Referenced, referenced, PF_HEAD)
PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
PAGEFLAG(Workingset, workingset, PF_HEAD)
TESTCLEARFLAG(Workingset, workingset, PF_HEAD)
__PAGEFLAG(Slab, slab, PF_NO_TAIL)
__PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)
PAGEFLAG(Checked, checked, PF_NO_COMPOUND) /* Used by some filesystems */
/* Xen */
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)
__SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
__CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
__SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
* 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, PF_ANY) __SETPAGEFLAG(Private, private, PF_ANY)
__CLEARPAGEFLAG(Private, private, PF_ANY)
PAGEFLAG(Private2, private_2, PF_ANY) TESTSCFLAG(Private2, private_2, PF_ANY)
PAGEFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
TESTCLEARFLAG(OwnerPriv1, owner_priv_1, PF_ANY)
* 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)
PAGEFLAG(MappedToDisk, mappedtodisk, PF_NO_TAIL)
/* PG_readahead is only used for reads; PG_reclaim is only for writes */
PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL)
PAGEFLAG(Readahead, reclaim, PF_NO_COMPOUND)
* 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))
static __always_inline int PageSwapCache(struct page *page)
page = compound_head(page);
return PageSwapBacked(page) && test_bit(PG_swapcache, &page->flags);
SETPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
CLEARPAGEFLAG(SwapCache, swapcache, PF_NO_TAIL)
PAGEFLAG(Unevictable, unevictable, PF_HEAD)
__CLEARPAGEFLAG(Unevictable, unevictable, PF_HEAD)
TESTCLEARFLAG(Unevictable, unevictable, PF_HEAD)
PAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
__CLEARPAGEFLAG(Mlocked, mlocked, PF_NO_TAIL)
TESTSCFLAG(Mlocked, mlocked, PF_NO_TAIL)
PAGEFLAG(Uncached, uncached, PF_NO_COMPOUND)
PAGEFLAG(HWPoison, hwpoison, PF_ANY)
TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
#define __PG_HWPOISON (1UL << PG_hwpoison)
extern bool take_page_off_buddy(struct page *page);
#define __PG_HWPOISON 0
#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
PAGEFLAG(Idle, idle, PF_ANY)
* 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)
* 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_MOVABLE 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 used for non-lru movable
* page and then page->mapping points a struct address_space.
* 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.
static __always_inline int PageMappingFlags(struct page *page)
return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != 0;
static __always_inline int PageAnon(struct page *page)
page = compound_head(page);
return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
static __always_inline int __PageMovable(struct page *page)
return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
* 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 int PageKsm(struct page *page)
page = compound_head(page);
return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
u64 stable_page_flags(struct page *page);
static inline int PageUptodate(struct page *page)
int ret;
page = compound_head(page);
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)
return ret;
static __always_inline void __SetPageUptodate(struct page *page)
VM_BUG_ON_PAGE(PageTail(page), page);
__set_bit(PG_uptodate, &page->flags);
static __always_inline void SetPageUptodate(struct page *page)
VM_BUG_ON_PAGE(PageTail(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.
set_bit(PG_uptodate, &page->flags);
CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
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)
static inline void set_page_writeback_keepwrite(struct page *page)
static __always_inline void set_compound_head(struct page *page, struct page *head)
WRITE_ONCE(page->compound_head, (unsigned long)head + 1);
static __always_inline void clear_compound_head(struct page *page)
WRITE_ONCE(page->compound_head, 0);
static inline void ClearPageCompound(struct page *page)
#define PG_head_mask ((1UL << PG_head))
int PageHuge(struct page *page);
int PageHeadHuge(struct page *page);
bool page_huge_active(struct page *page);
static inline bool page_huge_active(struct page *page)
return 0;
* 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);
* PageTransCompoundMap is the same as PageTransCompound, but it also
* guarantees the primary MMU has the entire compound page mapped
* through pmd_trans_huge, which in turn guarantees the secondary MMUs
* can also map the entire compound page. This allows the secondary
* MMUs to call get_user_pages() only once for each compound page and
* to immediately map the entire compound page with a single secondary
* MMU fault. If there will be a pmd split later, the secondary MMUs
* will get an update through the MMU notifier invalidation through
* split_huge_pmd().
* Unlike PageTransCompound, this is safe to be called only while
* split_huge_pmd() cannot run from under us, like if protected by the
* MMU notifier, otherwise it may result in page->_mapcount check false
* positives.
* We have to treat page cache THP differently since every subpage of it
* would get _mapcount inc'ed once it is PMD mapped. But, it may be PTE
* mapped in the current process so comparing subpage's _mapcount to
* compound_mapcount to filter out PTE mapped case.
static inline int PageTransCompoundMap(struct page *page)
struct page *head;
if (!PageTransCompound(page))
return 0;
if (PageAnon(page))
return atomic_read(&page->_mapcount) < 0;
head = compound_head(page);
/* File THP is PMD mapped and not PTE mapped */
return atomic_read(&page->_mapcount) ==
* 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);
* PageDoubleMap indicates that the compound page is mapped with PTEs as well
* as PMDs.
* This is required for optimization of rmap operations for THP: we can postpone
* per small page mapcount accounting (and its overhead from atomic operations)
* until the first PMD split.
* For the page PageDoubleMap means ->_mapcount in all sub-pages is offset up
* by one. This reference will go away with last compound_mapcount.
* See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
PAGEFLAG(DoubleMap, double_map, PF_SECOND)
TESTSCFLAG(DoubleMap, double_map, PF_SECOND)
* For pages that are never mapped to userspace (and aren't PageSlab),
* page_type may be used. Because it is initialised to -1, we invert the
* sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
* __ClearPageFoo *sets* the bit used for PageFoo. We reserve a few high and
* low bits so that an underflow or overflow of page_mapcount() won't be
* mistaken for a page type value.
#define PAGE_TYPE_BASE 0xf0000000
/* Reserve 0x0000007f to catch underflows of page_mapcount */
#define PG_buddy 0x00000080
#define PG_offline 0x00000100
#define PG_kmemcg 0x00000200
#define PG_table 0x00000400
#define PG_guard 0x00000800
#define PageType(page, flag) \
((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
static inline int page_has_type(struct page *page)
return (int)page->page_type < PAGE_MAPCOUNT_RESERVE;
#define PAGE_TYPE_OPS(uname, lname) \
static __always_inline int Page##uname(struct page *page) \
{ \
return PageType(page, PG_##lname); \
} \
static __always_inline void __SetPage##uname(struct page *page) \
{ \
VM_BUG_ON_PAGE(!PageType(page, 0), page); \
page->page_type &= ~PG_##lname; \
} \
static __always_inline void __ClearPage##uname(struct page *page) \
{ \
VM_BUG_ON_PAGE(!Page##uname(page), page); \
page->page_type |= PG_##lname; \
* PageBuddy() indicates that the page is free and in the buddy system
* (see mm/page_alloc.c).
PAGE_TYPE_OPS(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.
* 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 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 to re-set the pages PageOffline() and not giving them to the
* buddy via online_page_callback_t.
PAGE_TYPE_OPS(Offline, offline)
* If kmemcg is enabled, the buddy allocator will set PageKmemcg() on
* pages allocated with __GFP_ACCOUNT. It gets cleared on page free.
PAGE_TYPE_OPS(Kmemcg, kmemcg)
* Marks pages in use as page tables.
PAGE_TYPE_OPS(Table, table)
* Marks guardpages used with debug_pagealloc.
PAGE_TYPE_OPS(Guard, guard)
extern bool is_free_buddy_page(struct page *page);
__PAGEFLAG(Isolated, isolated, PF_ANY);
* 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);
static inline void __ClearPageSlabPfmemalloc(struct page *page)
VM_BUG_ON_PAGE(!PageSlab(page), page);
static inline void ClearPageSlabPfmemalloc(struct page *page)
VM_BUG_ON_PAGE(!PageSlab(page), page);
#define __PG_MLOCKED (1UL << PG_mlocked)
#define __PG_MLOCKED 0
* Flags checked when a page is freed. Pages being freed should not have
* these flags set. It they are, there is a problem.
(1UL << PG_lru | 1UL << PG_locked | \
1UL << PG_private | 1UL << PG_private_2 | \
1UL << PG_writeback | 1UL << PG_reserved | \
1UL << PG_slab | 1UL << PG_active | \
1UL << PG_unevictable | __PG_MLOCKED)
* 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.
(((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
(1UL << PG_private | 1UL << 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);
#undef PF_ANY
#undef PF_HEAD
#undef PF_NO_TAIL
#undef PF_SECOND
#endif /* !__GENERATING_BOUNDS_H */
#endif /* PAGE_FLAGS_H */