1 files changed, 6 insertions, 2 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 8c283a910b91..528e2aed36c3 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -324,10 +324,14 @@ struct css_set {
         struct hlist_node hlist;
 
         /*
-         * List running through all tasks using this cgroup
-         * group. Protected by css_set_lock
+         * Lists running through all tasks using this cgroup group.
+         * mg_tasks lists tasks which belong to this cset but are in the
+         * process of being migrated out or in.  Protected by
+         * css_set_rwsem, but, during migration, once tasks are moved to
+         * mg_tasks, it can be read safely while holding cgroup_mutex.
          */
         struct list_head tasks;
+        struct list_head mg_tasks;
 
         /*
          * List of cgrp_cset_links pointing at cgroups referenced from this