mm: uninitialized struct page poisoning sanity checking

[linux-2.6-microblaze.git] / include / linux / page-flags.h

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 50c2b87..e34a277 100644 (file)
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -156,9 +156,18 @@ static __always_inline int PageCompound(struct page *page)
        return test_bit(PG_head, &page->flags) || PageTail(page);
 }
 
+#define        PAGE_POISON_PATTERN     -1l
+static inline int PagePoisoned(const struct page *page)
+{
+       return page->flags == PAGE_POISON_PATTERN;
+}
+
 /*
  * Page flags policies wrt compound pages
  *
+ * PF_POISONED_CHECK
+ *     check if this struct page poisoned/uninitialized
+ *
  * PF_ANY:
  *     the page flag is relevant for small, head and tail pages.
  *
@@ -176,17 +185,20 @@ static __always_inline int PageCompound(struct page *page)
  * PF_NO_COMPOUND:
  *     the page flag is not relevant for compound pages.
  */
-#define PF_ANY(page, enforce)  page
-#define PF_HEAD(page, enforce) compound_head(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);                \
-               page;})
+               PF_POISONED_CHECK(page); })
 #define PF_NO_TAIL(page, enforce) ({                                   \
                VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page);     \
-               compound_head(page);})
+               PF_POISONED_CHECK(compound_head(page)); })
 #define PF_NO_COMPOUND(page, enforce) ({                               \
                VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \
-               page;})
+               PF_POISONED_CHECK(page); })
 
 /*
  * Macros to create function definitions for page flags