Merge commit 'v2.6.32' into reiserfs/kill-bkl

Merge-reason: The tree was based 2.6.31. It's better to be up to date
with 2.6.32. Although no conflicting changes were made in between,
it gives benchmarking results closer to the lastest kernel behaviour.

1 files changed, 79 insertions, 0 deletions

diff --git a/include/linux/ksm.h b/include/linux/ksm.h
new file mode 100644
index 000000000000..a485c14ecd5d
--- /dev/null
+++ b/include/linux/ksm.h
@@ -0,0 +1,79 @@
+#ifndef __LINUX_KSM_H
+#define __LINUX_KSM_H
+/*
+ * Memory merging support.
+ *
+ * This code enables dynamic sharing of identical pages found in different
+ * memory areas, even if they are not shared by fork().
+ */
+
+#include <linux/bitops.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/vmstat.h>
+
+#ifdef CONFIG_KSM
+int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
+                unsigned long end, int advice, unsigned long *vm_flags);
+int __ksm_enter(struct mm_struct *mm);
+void __ksm_exit(struct mm_struct *mm);
+
+static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
+{
+        if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags))
+                return __ksm_enter(mm);
+        return 0;
+}
+
+static inline void ksm_exit(struct mm_struct *mm)
+{
+        if (test_bit(MMF_VM_MERGEABLE, &mm->flags))
+                __ksm_exit(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.
+ */
+static inline int PageKsm(struct page *page)
+{
+        return ((unsigned long)page->mapping == PAGE_MAPPING_ANON);
+}
+
+/*
+ * But we have to avoid the checking which page_add_anon_rmap() performs.
+ */
+static inline void page_add_ksm_rmap(struct page *page)
+{
+        if (atomic_inc_and_test(&page->_mapcount)) {
+                page->mapping = (void *) PAGE_MAPPING_ANON;
+                __inc_zone_page_state(page, NR_ANON_PAGES);
+        }
+}
+#else  /* !CONFIG_KSM */
+
+static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
+                unsigned long end, int advice, unsigned long *vm_flags)
+{
+        return 0;
+}
+
+static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
+{
+        return 0;
+}
+
+static inline void ksm_exit(struct mm_struct *mm)
+{
+}
+
+static inline int PageKsm(struct page *page)
+{
+        return 0;
+}
+
+/* No stub required for page_add_ksm_rmap(page) */
+#endif /* !CONFIG_KSM */
+
+#endif