#ifndef PAGE_FLAGS_H
#define PAGE_FLAGS_H
-#include <linux/percpu.h>
-#include <linux/cache.h>
-#include <asm/pgtable.h>
+#include <linux/types.h>
+#ifndef __GENERATING_BOUNDS_H
+#include <linux/mm_types.h>
+#include <linux/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 if page->private contains a valid value.
+ * 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 disk I/O, PG_locked is used. This bit is set before I/O and
- * reset when I/O completes. page_waitqueue(page) is a wait queue of all tasks
- * waiting for the I/O on this page to complete.
+ * 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.
*
- * For choosing which pages to swap out, inode pages carry a PG_referenced bit,
- * which is set any time the system accesses that page through the (mapping,
- * index) hash table. This referenced bit, together with the referenced bit
- * in the page tables, is used to manipulate page->age and move the page across
- * the active, inactive_dirty and inactive_clean lists.
- *
- * Note that the referenced bit, the page->lru list_head and the active,
- * inactive_dirty and inactive_clean lists are protected by the
- * zone->lru_lock, and *NOT* by the usual PG_locked bit!
+ * 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.
*
* 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_buddy is set to indicate that the page is free and in the buddy system
+ * (see mm/page_alloc.c).
+ *
*/
/*
* Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
- * locked- and dirty-page accounting. The top eight bits of page->flags are
- * used for page->zone, so putting flag bits there doesn't work.
+ * 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).
*/
-#define PG_locked 0 /* Page is locked. Don't touch. */
-#define PG_error 1
-#define PG_referenced 2
-#define PG_uptodate 3
-
-#define PG_dirty 4
-#define PG_lru 5
-#define PG_active 6
-#define PG_slab 7 /* slab debug (Suparna wants this) */
-
-#define PG_highmem 8
-#define PG_checked 9 /* kill me in 2.5.<early>. */
-#define PG_arch_1 10
-#define PG_reserved 11
-
-#define PG_private 12 /* Has something at ->private */
-#define PG_writeback 13 /* Page is under writeback */
-#define PG_nosave 14 /* Used for system suspend/resume */
-#define PG_compound 15 /* Part of a compound page */
-
-#define PG_swapcache 16 /* Swap page: swp_entry_t in private */
-#define PG_mappedtodisk 17 /* Has blocks allocated on-disk */
-#define PG_reclaim 18 /* To be reclaimed asap */
-#define PG_nosave_free 19 /* Free, should not be written */
-#define PG_uncached 20 /* Page has been mapped as uncached */
+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_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_buddy, /* Page is free, on buddy lists */
+#ifdef CONFIG_IA64_UNCACHED_ALLOCATOR
+ PG_uncached, /* Page has been mapped as uncached */
+#endif
+ __NR_PAGEFLAGS,
+
+ /* Filesystems */
+ PG_checked = PG_owner_priv_1,
+
+ /* XEN */
+ PG_pinned = PG_owner_priv_1,
+ PG_savepinned = PG_dirty,
+
+ /* SLOB */
+ PG_slob_page = PG_active,
+ PG_slob_free = PG_private,
+
+ /* SLUB */
+ PG_slub_frozen = PG_active,
+ PG_slub_debug = PG_error,
+};
+
+#ifndef __GENERATING_BOUNDS_H
/*
- * Global page accounting. One instance per CPU. Only unsigned longs are
- * allowed.
+ * Macros to create function definitions for page flags
*/
-struct page_state {
- unsigned long nr_dirty; /* Dirty writeable pages */
- unsigned long nr_writeback; /* Pages under writeback */
- unsigned long nr_unstable; /* NFS unstable pages */
- unsigned long nr_page_table_pages;/* Pages used for pagetables */
- unsigned long nr_mapped; /* mapped into pagetables */
- unsigned long nr_slab; /* In slab */
-#define GET_PAGE_STATE_LAST nr_slab
+#define TESTPAGEFLAG(uname, lname) \
+static inline int Page##uname(struct page *page) \
+ { return test_bit(PG_##lname, &page->flags); }
- /*
- * The below are zeroed by get_page_state(). Use get_full_page_state()
- * to add up all these.
- */
- unsigned long pgpgin; /* Disk reads */
- unsigned long pgpgout; /* Disk writes */
- unsigned long pswpin; /* swap reads */
- unsigned long pswpout; /* swap writes */
- unsigned long pgalloc_high; /* page allocations */
-
- unsigned long pgalloc_normal;
- unsigned long pgalloc_dma;
- unsigned long pgfree; /* page freeings */
- unsigned long pgactivate; /* pages moved inactive->active */
- unsigned long pgdeactivate; /* pages moved active->inactive */
-
- unsigned long pgfault; /* faults (major+minor) */
- unsigned long pgmajfault; /* faults (major only) */
- unsigned long pgrefill_high; /* inspected in refill_inactive_zone */
- unsigned long pgrefill_normal;
- unsigned long pgrefill_dma;
-
- unsigned long pgsteal_high; /* total highmem pages reclaimed */
- unsigned long pgsteal_normal;
- unsigned long pgsteal_dma;
- unsigned long pgscan_kswapd_high;/* total highmem pages scanned */
- unsigned long pgscan_kswapd_normal;
-
- unsigned long pgscan_kswapd_dma;
- unsigned long pgscan_direct_high;/* total highmem pages scanned */
- unsigned long pgscan_direct_normal;
- unsigned long pgscan_direct_dma;
- unsigned long pginodesteal; /* pages reclaimed via inode freeing */
-
- unsigned long slabs_scanned; /* slab objects scanned */
- unsigned long kswapd_steal; /* pages reclaimed by kswapd */
- unsigned long kswapd_inodesteal;/* reclaimed via kswapd inode freeing */
- unsigned long pageoutrun; /* kswapd's calls to page reclaim */
- unsigned long allocstall; /* direct reclaim calls */
-
- unsigned long pgrotated; /* pages rotated to tail of the LRU */
- unsigned long nr_bounce; /* pages for bounce buffers */
-};
+#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); }
-extern void get_page_state(struct page_state *ret);
-extern void get_full_page_state(struct page_state *ret);
-extern unsigned long __read_page_state(unsigned offset);
-extern void __mod_page_state(unsigned offset, unsigned long delta);
-
-#define read_page_state(member) \
- __read_page_state(offsetof(struct page_state, member))
-
-#define mod_page_state(member, delta) \
- __mod_page_state(offsetof(struct page_state, member), (delta))
-
-#define inc_page_state(member) mod_page_state(member, 1UL)
-#define dec_page_state(member) mod_page_state(member, 0UL - 1)
-#define add_page_state(member,delta) mod_page_state(member, (delta))
-#define sub_page_state(member,delta) mod_page_state(member, 0UL - (delta))
-
-#define mod_page_state_zone(zone, member, delta) \
- do { \
- unsigned offset; \
- if (is_highmem(zone)) \
- offset = offsetof(struct page_state, member##_high); \
- else if (is_normal(zone)) \
- offset = offsetof(struct page_state, member##_normal); \
- else \
- offset = offsetof(struct page_state, member##_dma); \
- __mod_page_state(offset, (delta)); \
- } while (0)
+#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 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)
+
+struct page; /* forward declaration */
+
+TESTPAGEFLAG(Locked, locked)
+PAGEFLAG(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)
+__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(Private, private) __CLEARPAGEFLAG(Private, private)
+ __SETPAGEFLAG(Private, private)
+
+__PAGEFLAG(SlobPage, slob_page)
+__PAGEFLAG(SlobFree, slob_free)
+
+__PAGEFLAG(SlubFrozen, slub_frozen)
+__PAGEFLAG(SlubDebug, slub_debug)
/*
- * Manipulation of page state flags
+ * Only test-and-set exist for PG_writeback. The unconditional operators are
+ * risky: they bypass page accounting.
*/
-#define PageLocked(page) \
- test_bit(PG_locked, &(page)->flags)
-#define SetPageLocked(page) \
- set_bit(PG_locked, &(page)->flags)
-#define TestSetPageLocked(page) \
- test_and_set_bit(PG_locked, &(page)->flags)
-#define ClearPageLocked(page) \
- clear_bit(PG_locked, &(page)->flags)
-#define TestClearPageLocked(page) \
- test_and_clear_bit(PG_locked, &(page)->flags)
-
-#define PageError(page) test_bit(PG_error, &(page)->flags)
-#define SetPageError(page) set_bit(PG_error, &(page)->flags)
-#define ClearPageError(page) clear_bit(PG_error, &(page)->flags)
-
-#define PageReferenced(page) test_bit(PG_referenced, &(page)->flags)
-#define SetPageReferenced(page) set_bit(PG_referenced, &(page)->flags)
-#define ClearPageReferenced(page) clear_bit(PG_referenced, &(page)->flags)
-#define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
-
-#define PageUptodate(page) test_bit(PG_uptodate, &(page)->flags)
-#ifndef SetPageUptodate
-#define SetPageUptodate(page) set_bit(PG_uptodate, &(page)->flags)
-#endif
-#define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)
-
-#define PageDirty(page) test_bit(PG_dirty, &(page)->flags)
-#define SetPageDirty(page) set_bit(PG_dirty, &(page)->flags)
-#define TestSetPageDirty(page) test_and_set_bit(PG_dirty, &(page)->flags)
-#define ClearPageDirty(page) clear_bit(PG_dirty, &(page)->flags)
-#define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
-
-#define SetPageLRU(page) set_bit(PG_lru, &(page)->flags)
-#define PageLRU(page) test_bit(PG_lru, &(page)->flags)
-#define TestSetPageLRU(page) test_and_set_bit(PG_lru, &(page)->flags)
-#define TestClearPageLRU(page) test_and_clear_bit(PG_lru, &(page)->flags)
-
-#define PageActive(page) test_bit(PG_active, &(page)->flags)
-#define SetPageActive(page) set_bit(PG_active, &(page)->flags)
-#define ClearPageActive(page) clear_bit(PG_active, &(page)->flags)
-#define TestClearPageActive(page) test_and_clear_bit(PG_active, &(page)->flags)
-#define TestSetPageActive(page) test_and_set_bit(PG_active, &(page)->flags)
-
-#define PageSlab(page) test_bit(PG_slab, &(page)->flags)
-#define SetPageSlab(page) set_bit(PG_slab, &(page)->flags)
-#define ClearPageSlab(page) clear_bit(PG_slab, &(page)->flags)
-#define TestClearPageSlab(page) test_and_clear_bit(PG_slab, &(page)->flags)
-#define TestSetPageSlab(page) test_and_set_bit(PG_slab, &(page)->flags)
+TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback)
+__PAGEFLAG(Buddy, buddy)
+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
-#define PageHighMem(page) test_bit(PG_highmem, &(page)->flags)
+/*
+ * 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
-#define PageHighMem(page) 0 /* needed to optimize away at compile time */
+PAGEFLAG_FALSE(HighMem)
#endif
-#define PageChecked(page) test_bit(PG_checked, &(page)->flags)
-#define SetPageChecked(page) set_bit(PG_checked, &(page)->flags)
-#define ClearPageChecked(page) clear_bit(PG_checked, &(page)->flags)
-
-#define PageReserved(page) test_bit(PG_reserved, &(page)->flags)
-#define SetPageReserved(page) set_bit(PG_reserved, &(page)->flags)
-#define ClearPageReserved(page) clear_bit(PG_reserved, &(page)->flags)
-#define __ClearPageReserved(page) __clear_bit(PG_reserved, &(page)->flags)
-
-#define SetPagePrivate(page) set_bit(PG_private, &(page)->flags)
-#define ClearPagePrivate(page) clear_bit(PG_private, &(page)->flags)
-#define PagePrivate(page) test_bit(PG_private, &(page)->flags)
-#define __SetPagePrivate(page) __set_bit(PG_private, &(page)->flags)
-#define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
-
-#define PageWriteback(page) test_bit(PG_writeback, &(page)->flags)
-#define SetPageWriteback(page) \
- do { \
- if (!test_and_set_bit(PG_writeback, \
- &(page)->flags)) \
- inc_page_state(nr_writeback); \
- } while (0)
-#define TestSetPageWriteback(page) \
- ({ \
- int ret; \
- ret = test_and_set_bit(PG_writeback, \
- &(page)->flags); \
- if (!ret) \
- inc_page_state(nr_writeback); \
- ret; \
- })
-#define ClearPageWriteback(page) \
- do { \
- if (test_and_clear_bit(PG_writeback, \
- &(page)->flags)) \
- dec_page_state(nr_writeback); \
- } while (0)
-#define TestClearPageWriteback(page) \
- ({ \
- int ret; \
- ret = test_and_clear_bit(PG_writeback, \
- &(page)->flags); \
- if (ret) \
- dec_page_state(nr_writeback); \
- ret; \
- })
-
-#define PageNosave(page) test_bit(PG_nosave, &(page)->flags)
-#define SetPageNosave(page) set_bit(PG_nosave, &(page)->flags)
-#define TestSetPageNosave(page) test_and_set_bit(PG_nosave, &(page)->flags)
-#define ClearPageNosave(page) clear_bit(PG_nosave, &(page)->flags)
-#define TestClearPageNosave(page) test_and_clear_bit(PG_nosave, &(page)->flags)
-
-#define PageNosaveFree(page) test_bit(PG_nosave_free, &(page)->flags)
-#define SetPageNosaveFree(page) set_bit(PG_nosave_free, &(page)->flags)
-#define ClearPageNosaveFree(page) clear_bit(PG_nosave_free, &(page)->flags)
-
-#define PageMappedToDisk(page) test_bit(PG_mappedtodisk, &(page)->flags)
-#define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
-#define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
-
-#define PageReclaim(page) test_bit(PG_reclaim, &(page)->flags)
-#define SetPageReclaim(page) set_bit(PG_reclaim, &(page)->flags)
-#define ClearPageReclaim(page) clear_bit(PG_reclaim, &(page)->flags)
-#define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)
-
-#ifdef CONFIG_HUGETLB_PAGE
-#define PageCompound(page) test_bit(PG_compound, &(page)->flags)
+#ifdef CONFIG_SWAP
+PAGEFLAG(SwapCache, swapcache)
#else
-#define PageCompound(page) 0
+PAGEFLAG_FALSE(SwapCache)
#endif
-#define SetPageCompound(page) set_bit(PG_compound, &(page)->flags)
-#define ClearPageCompound(page) clear_bit(PG_compound, &(page)->flags)
-#ifdef CONFIG_SWAP
-#define PageSwapCache(page) test_bit(PG_swapcache, &(page)->flags)
-#define SetPageSwapCache(page) set_bit(PG_swapcache, &(page)->flags)
-#define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags)
+#ifdef CONFIG_IA64_UNCACHED_ALLOCATOR
+PAGEFLAG(Uncached, uncached)
#else
-#define PageSwapCache(page) 0
+PAGEFLAG_FALSE(Uncached)
#endif
-#define PageUncached(page) test_bit(PG_uncached, &(page)->flags)
-#define SetPageUncached(page) set_bit(PG_uncached, &(page)->flags)
-#define ClearPageUncached(page) clear_bit(PG_uncached, &(page)->flags)
+static inline int PageUptodate(struct page *page)
+{
+ int ret = test_bit(PG_uptodate, &(page)->flags);
-struct page; /* forward declaration */
+ /*
+ * 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();
-int test_clear_page_dirty(struct page *page);
-int test_clear_page_writeback(struct page *page);
-int test_set_page_writeback(struct page *page);
+ return ret;
+}
-static inline void clear_page_dirty(struct page *page)
+static inline void __SetPageUptodate(struct page *page)
{
- test_clear_page_dirty(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_clear_dirty(page);
+#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)
+__PAGEFLAG(Tail, tail)
+
+static inline int PageCompound(struct page *page)
+{
+ return page->flags & ((1L << PG_head) | (1L << PG_tail));
+
+}
+#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;
+}
+
+#endif /* !PAGEFLAGS_EXTENDED */
+
+#define PAGE_FLAGS (1 << PG_lru | 1 << PG_private | 1 << PG_locked | \
+ 1 << PG_buddy | 1 << PG_writeback | \
+ 1 << PG_slab | 1 << PG_swapcache | 1 << PG_active)
+
+/*
+ * Flags checked in bad_page(). Pages on the free list should not have
+ * these flags set. It they are, there is a problem.
+ */
+#define PAGE_FLAGS_CLEAR_WHEN_BAD (PAGE_FLAGS | 1 << PG_reclaim | 1 << PG_dirty)
+
+/*
+ * 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 (PAGE_FLAGS | 1 << PG_reserved)
+
+/*
+ * 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, there
+ * is a problem.
+ */
+#define PAGE_FLAGS_CHECK_AT_PREP (PAGE_FLAGS | 1 << PG_reserved | 1 << PG_dirty)
+
+#endif /* !__GENERATING_BOUNDS_H */
#endif /* PAGE_FLAGS_H */
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