ksm: stable_node point to page and back

[pandora-kernel.git] / include / linux / ksm.h

diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index 1401a31..ef55ce1 100644 (file)
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -12,6 +12,8 @@
 #include <linux/sched.h>
 #include <linux/vmstat.h>
 
+struct stable_node;
+
 #ifdef CONFIG_KSM
 int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
                unsigned long end, int advice, unsigned long *vm_flags);
@@ -34,7 +36,8 @@ static inline void ksm_exit(struct mm_struct *mm)
 /*
  * 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, with NULL anon_vma.
+ * 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 inline int PageKsm(struct page *page)
 {
@@ -42,15 +45,22 @@ static inline int PageKsm(struct page *page)
                                (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
 }
 
-/*
- * But we have to avoid the checking which page_add_anon_rmap() performs.
- */
+static inline struct stable_node *page_stable_node(struct page *page)
+{
+       return PageKsm(page) ? page_rmapping(page) : NULL;
+}
+
+static inline void set_page_stable_node(struct page *page,
+                                       struct stable_node *stable_node)
+{
+       page->mapping = (void *)stable_node +
+                               (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
+}
+
 static inline void page_add_ksm_rmap(struct page *page)
 {
-       if (atomic_inc_and_test(&page->_mapcount)) {
-               page->mapping = (void *) (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
+       if (atomic_inc_and_test(&page->_mapcount))
                __inc_zone_page_state(page, NR_ANON_PAGES);
-       }
 }
 #else  /* !CONFIG_KSM */