3 files changed, 47 insertions, 0 deletions

diff --git a/mm/rmap.c b/mm/rmap.c
index 13fad5fcdf79..f4b91d7aa5cf 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -206,6 +206,35 @@ out:
         return anon_vma;
 }
 
+#ifdef CONFIG_MIGRATION
+/*
+ * Remove an anonymous page from swap replacing the swap pte's
+ * through real pte's pointing to valid pages and then releasing
+ * the page from the swap cache.
+ *
+ * Must hold page lock on page.
+ */
+void remove_from_swap(struct page *page)
+{
+        struct anon_vma *anon_vma;
+        struct vm_area_struct *vma;
+
+        if (!PageAnon(page) || !PageSwapCache(page))
+                return;
+
+        anon_vma = page_lock_anon_vma(page);
+        if (!anon_vma)
+                return;
+
+        list_for_each_entry(vma, &anon_vma->head, anon_vma_node)
+                remove_vma_swap(vma, page);
+
+        spin_unlock(&anon_vma->lock);
+
+        delete_from_swap_cache(page);
+}
+#endif
+
 /*
  * At what user virtual address is page expected in vma?
  */
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 9678182e0eef..1f9cf0d073b8 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -554,6 +554,15 @@ static int unuse_mm(struct mm_struct *mm,
         return 0;
 }
 
+#ifdef CONFIG_MIGRATION
+int remove_vma_swap(struct vm_area_struct *vma, struct page *page)
+{
+        swp_entry_t entry = { .val = page_private(page) };
+
+        return unuse_vma(vma, entry, page);
+}
+#endif
+
 /*
  * Scan swap_map from current position to next entry still in use.
  * Recycle to start on reaching the end, returning 0 when empty.
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 8f326ce2b690..5e98b86feb74 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -804,6 +804,15 @@ int migrate_page(struct page *newpage, struct page *page)
 
         migrate_page_copy(newpage, page);
 
+        /*
+         * Remove auxiliary swap entries and replace
+         * them with real ptes.
+         *
+         * Note that a real pte entry will allow processes that are not
+         * waiting on the page lock to use the new page via the page tables
+         * before the new page is unlocked.
+         */
+        remove_from_swap(newpage);
         return 0;
 }