1 files changed, 14 insertions, 0 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 4334576f5d6a..644281003f5d 100644
--- a/kernel/cpuset.c
+++ b/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;