1 files changed, 3 insertions, 18 deletions

diff --git a/mm/migrate.c b/mm/migrate.c
index e545ce7..20a03eb 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -731,20 +731,6 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
 		lock_page(page);
 	}
 
-	/*
-	 * Only memory hotplug's offline_pages() caller has locked out KSM,
-	 * and can safely migrate a KSM page.  The other cases have skipped
-	 * PageKsm along with PageReserved - but it is only now when we have
-	 * the page lock that we can be certain it will not go KSM beneath us
-	 * (KSM will not upgrade a page from PageAnon to PageKsm when it sees
-	 * its pagecount raised, but only here do we take the page lock which
-	 * serializes that).
-	 */
-	if (PageKsm(page) && !offlining) {
-		rc = -EBUSY;
-		goto unlock;
-	}
-
 	/* charge against new page */
 	mem_cgroup_prepare_migration(page, newpage, &mem);
 
@@ -771,7 +757,7 @@ static int __unmap_and_move(struct page *page, struct page *newpage,
 	 * File Caches may use write_page() or lock_page() in migration, then,
 	 * just care Anon page here.
 	 */
-	if (PageAnon(page)) {
+	if (PageAnon(page) && !PageKsm(page)) {
 		/*
 		 * Only page_lock_anon_vma_read() understands the subtleties of
 		 * getting a hold on an anon_vma from outside one of its mms.
@@ -851,7 +837,6 @@ uncharge:
 	mem_cgroup_end_migration(mem, page, newpage,
 				 (rc == MIGRATEPAGE_SUCCESS ||
 				  rc == MIGRATEPAGE_BALLOON_SUCCESS));
-unlock:
 	unlock_page(page);
 out:
 	return rc;
@@ -1155,7 +1140,7 @@ static int do_move_page_to_node_array(struct mm_struct *mm,
 			goto set_status;
 
 		/* Use PageReserved to check for zero page */
-		if (PageReserved(page) || PageKsm(page))
+		if (PageReserved(page))
 			goto put_and_set;
 
 		pp->page = page;
@@ -1317,7 +1302,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
 
 		err = -ENOENT;
 		/* Use PageReserved to check for zero page */
-		if (!page || PageReserved(page) || PageKsm(page))
+		if (!page || PageReserved(page))
 			goto set_status;
 
 		err = page_to_nid(page);