1 files changed, 65 insertions, 0 deletions

diff --git a/mm/ksm.c b/mm/ksm.c
index 20f46a7b2799..dfdc292d3626 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1656,6 +1656,71 @@ out:
         return ret;
 }
 
+#ifdef CONFIG_MIGRATION
+int rmap_walk_ksm(struct page *page, int (*rmap_one)(struct page *,
+                  struct vm_area_struct *, unsigned long, void *), void *arg)
+{
+        struct stable_node *stable_node;
+        struct hlist_node *hlist;
+        struct rmap_item *rmap_item;
+        int ret = SWAP_AGAIN;
+        int search_new_forks = 0;
+
+        VM_BUG_ON(!PageKsm(page));
+        VM_BUG_ON(!PageLocked(page));
+
+        stable_node = page_stable_node(page);
+        if (!stable_node)
+                return ret;
+again:
+        hlist_for_each_entry(rmap_item, hlist, &stable_node->hlist, hlist) {
+                struct anon_vma *anon_vma = rmap_item->anon_vma;
+                struct vm_area_struct *vma;
+
+                spin_lock(&anon_vma->lock);
+                list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
+                        if (rmap_item->address < vma->vm_start ||
+                            rmap_item->address >= vma->vm_end)
+                                continue;
+                        /*
+                         * Initially we examine only the vma which covers this
+                         * rmap_item; but later, if there is still work to do,
+                         * we examine covering vmas in other mms: in case they
+                         * were forked from the original since ksmd passed.
+                         */
+                        if ((rmap_item->mm == vma->vm_mm) == search_new_forks)
+                                continue;
+
+                        ret = rmap_one(page, vma, rmap_item->address, arg);
+                        if (ret != SWAP_AGAIN) {
+                                spin_unlock(&anon_vma->lock);
+                                goto out;
+                        }
+                }
+                spin_unlock(&anon_vma->lock);
+        }
+        if (!search_new_forks++)
+                goto again;
+out:
+        return ret;
+}
+
+void ksm_migrate_page(struct page *newpage, struct page *oldpage)
+{
+        struct stable_node *stable_node;
+
+        VM_BUG_ON(!PageLocked(oldpage));
+        VM_BUG_ON(!PageLocked(newpage));
+        VM_BUG_ON(newpage->mapping != oldpage->mapping);
+
+        stable_node = page_stable_node(newpage);
+        if (stable_node) {
+                VM_BUG_ON(stable_node->page != oldpage);
+                stable_node->page = newpage;
+        }
+}
+#endif /* CONFIG_MIGRATION */
+
 #ifdef CONFIG_SYSFS
 /*
  * This all compiles without CONFIG_SYSFS, but is a waste of space.