diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2880396..e097c10 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3499,6 +3499,7 @@
 	return 1;
 }
 
+#ifdef CONFIG_SHMEM
 /**
  * check_move_unevictable_page - check page for evictability and move to appropriate zone lru list
  * @page: page to check evictability and move to appropriate lru list
@@ -3509,6 +3510,8 @@
  *
  * Restrictions: zone->lru_lock must be held, page must be on LRU and must
  * have PageUnevictable set.
+ *
+ * This function is only used for SysV IPC SHM_UNLOCK.
  */
 static void check_move_unevictable_page(struct page *page, struct zone *zone)
 {
@@ -3545,6 +3548,8 @@
  *
  * Scan all pages in mapping.  Check unevictable pages for
  * evictability and move them to the appropriate zone lru list.
+ *
+ * This function is only used for SysV IPC SHM_UNLOCK.
  */
 void scan_mapping_unevictable_pages(struct address_space *mapping)
 {
@@ -3590,9 +3595,14 @@
 		pagevec_release(&pvec);
 
 		count_vm_events(UNEVICTABLE_PGSCANNED, pg_scanned);
+		cond_resched();
 	}
-
 }
+#else
+void scan_mapping_unevictable_pages(struct address_space *mapping)
+{
+}
+#endif /* CONFIG_SHMEM */
 
 static void warn_scan_unevictable_pages(void)
 {