3 files changed, 58 insertions, 0 deletions

diff --git a/include/linux/ksm.h b/include/linux/ksm.h
new file mode 100644
index 000000000000..eb2a448981ee
--- /dev/null
+++ b/include/linux/ksm.h
@@ -0,0 +1,50 @@
+#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>
+
+#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);
+}
+#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)
+{
+}
+#endif /* !CONFIG_KSM */
+
+#endif
diff --git a/include/linux/mm.h b/include/linux/mm.h
index d3c8ae7c8015..d808cf832c4d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -103,6 +103,7 @@ extern unsigned int kobjsize(const void *objp);
 #define VM_MIXEDMAP     0x10000000      /* Can contain "struct page" and pure PFN pages */
 #define VM_SAO          0x20000000      /* Strong Access Ordering (powerpc) */
 #define VM_PFN_AT_MMAP  0x40000000      /* PFNMAP vma that is fully mapped at mmap time */
+#define VM_MERGEABLE    0x80000000      /* KSM may merge identical pages */
 
 #ifndef VM_STACK_DEFAULT_FLAGS          /* arch can override this */
 #define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8fe351c3914a..8f3e63cb33a6 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -434,7 +434,9 @@ extern int get_dumpable(struct mm_struct *mm);
 /* dumpable bits */
 #define MMF_DUMPABLE      0  /* core dump is permitted */
 #define MMF_DUMP_SECURELY 1  /* core file is readable only by root */
+
 #define MMF_DUMPABLE_BITS 2
+#define MMF_DUMPABLE_MASK ((1 << MMF_DUMPABLE_BITS) - 1)
 
 /* coredump filter bits */
 #define MMF_DUMP_ANON_PRIVATE   2
@@ -444,6 +446,7 @@ extern int get_dumpable(struct mm_struct *mm);
 #define MMF_DUMP_ELF_HEADERS    6
 #define MMF_DUMP_HUGETLB_PRIVATE 7
 #define MMF_DUMP_HUGETLB_SHARED  8
+
 #define MMF_DUMP_FILTER_SHIFT   MMF_DUMPABLE_BITS
 #define MMF_DUMP_FILTER_BITS    7
 #define MMF_DUMP_FILTER_MASK \
@@ -457,6 +460,10 @@ extern int get_dumpable(struct mm_struct *mm);
 #else
 # define MMF_DUMP_MASK_DEFAULT_ELF      0
 #endif
+                                        /* leave room for more dump flags */
+#define MMF_VM_MERGEABLE        16      /* KSM may merge identical pages */
+
+#define MMF_INIT_MASK           (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK)
 
 struct sighand_struct {
         atomic_t                count;