---

yaml
---
r: 350347
b: refs/heads/master
c: 02bb586
h: refs/heads/master
i:
  350345: bea5878
  350343: f44dfc4
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 452477fa68c6d8ef80adebd05194c1c157ad9a53
+refs/heads/master: 02bb586372a71595203b3ff19a9be48eaa076f6c

trunk/kernel/cpuset.c

@@ -266,6 +266,7 @@ static struct workqueue_struct *cpuset_propagate_hotplug_wq;
 
 static void cpuset_hotplug_workfn(struct work_struct *work);
 static void cpuset_propagate_hotplug_workfn(struct work_struct *work);
+static void schedule_cpuset_propagate_hotplug(struct cpuset *cs);
 
 static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);
 
@@ -1464,6 +1465,14 @@ static void cpuset_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
 	}
 
 	cs->attach_in_progress--;
+
+	/*
+	 * We may have raced with CPU/memory hotunplug.  Trigger hotplug
+	 * propagation if @cs doesn't have any CPU or memory.  It will move
+	 * the newly added tasks to the nearest parent which can execute.
+	 */
+	if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed))
+		schedule_cpuset_propagate_hotplug(cs);
 }
 
 /* The various types of files and directories in a cpuset file system */
@@ -1569,8 +1578,13 @@ static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft,
 	 * resources, wait for the previously scheduled operations before
 	 * proceeding, so that we don't end up keep removing tasks added
 	 * after execution capability is restored.
+	 *
+	 * Flushing cpuset_hotplug_work is enough to synchronize against
+	 * hotplug hanlding; however, cpuset_attach() may schedule
+	 * propagation work directly.  Flush the workqueue too.
 	 */
 	flush_work(&cpuset_hotplug_work);
+	flush_workqueue(cpuset_propagate_hotplug_wq);
 
 	if (!cgroup_lock_live_group(cgrp))
 		return -ENODEV;