3 files changed, 38 insertions, 6 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 8e580c07d171..8e2841a2f441 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -97,7 +97,11 @@ extern unsigned int kobjsize(const void *objp);
 #define VM_NORESERVE    0x00200000      /* should the VM suppress accounting */
 #define VM_HUGETLB      0x00400000      /* Huge TLB Page VM */
 #define VM_NONLINEAR    0x00800000      /* Is non-linear (remap_file_pages) */
+#ifdef CONFIG_MMU
+#define VM_LOCK_RMAP    0x01000000      /* Do not follow this rmap (mmu mmap) */
+#else
 #define VM_MAPPED_COPY  0x01000000      /* T if mapped copy of data (nommu mmap) */
+#endif
 #define VM_INSERTPAGE   0x02000000      /* The vma has had "vm_insert_page()" done on it */
 #define VM_ALWAYSDUMP   0x04000000      /* Always include in core dumps */
 
@@ -1216,7 +1220,7 @@ static inline void vma_nonlinear_insert(struct vm_area_struct *vma,
 
 /* mmap.c */
 extern int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin);
-extern void vma_adjust(struct vm_area_struct *vma, unsigned long start,
+extern int vma_adjust(struct vm_area_struct *vma, unsigned long start,
         unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert);
 extern struct vm_area_struct *vma_merge(struct mm_struct *,
         struct vm_area_struct *prev, unsigned long addr, unsigned long end,
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 19549d7275ab..048b46270aa5 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -163,7 +163,8 @@ struct vm_area_struct {
          * can only be in the i_mmap tree.  An anonymous MAP_PRIVATE, stack
          * or brk vma (with NULL file) can only be in an anon_vma list.
          */
-        struct list_head anon_vma_node; /* Serialized by anon_vma->lock */
+        struct list_head anon_vma_chain; /* Serialized by mmap_sem &
+                                          * page_table_lock */
         struct anon_vma *anon_vma;      /* Serialized by page_table_lock */
 
         /* Function pointers to deal with this struct. */
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index b019ae64e2ab..62da2001d55c 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -37,7 +37,27 @@ struct anon_vma {
          * is serialized by a system wide lock only visible to
          * mm_take_all_locks() (mm_all_locks_mutex).
          */
-        struct list_head head;  /* List of private "related" vmas */
+        struct list_head head;  /* Chain of private "related" vmas */
+};
+
+/*
+ * The copy-on-write semantics of fork mean that an anon_vma
+ * can become associated with multiple processes. Furthermore,
+ * each child process will have its own anon_vma, where new
+ * pages for that process are instantiated.
+ *
+ * This structure allows us to find the anon_vmas associated
+ * with a VMA, or the VMAs associated with an anon_vma.
+ * The "same_vma" list contains the anon_vma_chains linking
+ * all the anon_vmas associated with this VMA.
+ * The "same_anon_vma" list contains the anon_vma_chains
+ * which link all the VMAs associated with this anon_vma.
+ */
+struct anon_vma_chain {
+        struct vm_area_struct *vma;
+        struct anon_vma *anon_vma;
+        struct list_head same_vma;   /* locked by mmap_sem & page_table_lock */
+        struct list_head same_anon_vma; /* locked by anon_vma->lock */
 };
 
 #ifdef CONFIG_MMU
@@ -89,12 +109,19 @@ static inline void anon_vma_unlock(struct vm_area_struct *vma)
  */
 void anon_vma_init(void);       /* create anon_vma_cachep */
 int  anon_vma_prepare(struct vm_area_struct *);
-void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *);
-void anon_vma_unlink(struct vm_area_struct *);
-void anon_vma_link(struct vm_area_struct *);
+void unlink_anon_vmas(struct vm_area_struct *);
+int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
+int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
 void __anon_vma_link(struct vm_area_struct *);
 void anon_vma_free(struct anon_vma *);
 
+static inline void anon_vma_merge(struct vm_area_struct *vma,
+                                  struct vm_area_struct *next)
+{
+        VM_BUG_ON(vma->anon_vma != next->anon_vma);
+        unlink_anon_vmas(next);
+}
+
 /*
  * rmap interfaces called when adding or removing pte of page
  */