mm/debug-pagealloc: prepare boottime configurable on/off

[linux-2.6-block.git] / include / linux / page_ext.h

diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
index 2ccc8b414e5c7bc76b8377ae2585c700189c127c..61c0f05f90694701653d206009a79635f7b1f655 100644 (file)
--- a/include/linux/page_ext.h
+++ b/include/linux/page_ext.h
@@ -9,6 +9,21 @@ struct page_ext_operations {
 
 #ifdef CONFIG_PAGE_EXTENSION
 
+/*
+ * page_ext->flags bits:
+ *
+ * PAGE_EXT_DEBUG_POISON is set for poisoned pages. This is used to
+ * implement generic debug pagealloc feature. The pages are filled with
+ * poison patterns and set this flag after free_pages(). The poisoned
+ * pages are verified whether the patterns are not corrupted and clear
+ * the flag before alloc_pages().
+ */
+
+enum page_ext_flags {
+       PAGE_EXT_DEBUG_POISON,          /* Page is poisoned */
+       PAGE_EXT_DEBUG_GUARD,
+};
+
 /*
  * Page Extension can be considered as an extended mem_map.
  * A page_ext page is associated with every page descriptor. The