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authorVladimir Davydov <vdavydov@virtuozzo.com>2016-07-26 15:24:18 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-26 16:19:19 -0700
commit632c0a1affd861f81abdd136c886418571e19a51 (patch)
tree583d947ff0c673e009487666e730bf854195ca4a /include/linux/page-flags.h
parent99691addb42919251dcc082a70b7a11733dfcbcc (diff)
downloadop-kernel-dev-632c0a1affd861f81abdd136c886418571e19a51.zip
op-kernel-dev-632c0a1affd861f81abdd136c886418571e19a51.tar.gz
mm: clean up non-standard page->_mapcount users
- Add a proper comment to page->_mapcount. - Introduce a macro for generating helper functions. - Place all special page->_mapcount values next to each other so that readers can see all possible values and so we don't get duplicates. Link: http://lkml.kernel.org/r/502f49000e0b63e6c62e338fac6b420bf34fb526.1464079537.git.vdavydov@virtuozzo.com Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/page-flags.h')
-rw-r--r--include/linux/page-flags.h73
1 files changed, 32 insertions, 41 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index f36dbb3..96084ee 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -604,54 +604,45 @@ TESTPAGEFLAG_FALSE(DoubleMap)
#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.
+ * For pages that are never mapped to userspace, page->mapcount may be
+ * used for storing extra information about page type. Any value used
+ * for this purpose must be <= -2, but it's better start not too close
+ * to -2 so that an underflow of the page_mapcount() won't be mistaken
+ * for a special page.
*/
-#define PAGE_BUDDY_MAPCOUNT_VALUE (-128)
-
-static inline int PageBuddy(struct page *page)
-{
- return atomic_read(&page->_mapcount) == PAGE_BUDDY_MAPCOUNT_VALUE;
+#define PAGE_MAPCOUNT_OPS(uname, lname) \
+static __always_inline int Page##uname(struct page *page) \
+{ \
+ return atomic_read(&page->_mapcount) == \
+ PAGE_##lname##_MAPCOUNT_VALUE; \
+} \
+static __always_inline void __SetPage##uname(struct page *page) \
+{ \
+ VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page); \
+ atomic_set(&page->_mapcount, PAGE_##lname##_MAPCOUNT_VALUE); \
+} \
+static __always_inline void __ClearPage##uname(struct page *page) \
+{ \
+ VM_BUG_ON_PAGE(!Page##uname(page), page); \
+ atomic_set(&page->_mapcount, -1); \
}
-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);
-}
+/*
+ * PageBuddy() indicate that the page is free and in the buddy system
+ * (see mm/page_alloc.c).
+ */
+#define PAGE_BUDDY_MAPCOUNT_VALUE (-128)
+PAGE_MAPCOUNT_OPS(Buddy, BUDDY)
-static inline void __ClearPageBuddy(struct page *page)
-{
- VM_BUG_ON_PAGE(!PageBuddy(page), page);
- atomic_set(&page->_mapcount, -1);
-}
+/*
+ * PageBalloon() is set on pages that are on the balloon page list
+ * (see mm/balloon_compaction.c).
+ */
+#define PAGE_BALLOON_MAPCOUNT_VALUE (-256)
+PAGE_MAPCOUNT_OPS(Balloon, BALLOON)
extern bool is_free_buddy_page(struct page *page);
-#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);
-}
-
__PAGEFLAG(Isolated, isolated, PF_ANY);
/*
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