From: Oleg Nesterov Oops. I completely misread the ->cpus_allowed check in try_to_wake_up(), and so workqueue_cpu_callback() needs a simple fix: CPU_UP_CANCELED should rebind cwq->thread. Or, better, we should not bind the task until CPU_ONLINE. I'll send the patch soon, but it conflicts with Rafael's add-suspend-related-notifications-for-cpu-hotplug.patch , so I am sending this cleanup first to make them independent. Actually, I believe almost all subsystems could be simplified as well, most of them don't care about CPU_TASKS_FROZEN bit. Signed-off-by: Oleg Nesterov Cc: Rafael J. Wysocki Cc: Gautham R Shenoy Cc: Pavel Machek Signed-off-by: Andrew Morton --- kernel/workqueue.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletion(-) diff -puN kernel/workqueue.c~add-suspend-related-notifications-for-cpu-hotplug-cleanup kernel/workqueue.c --- a/kernel/workqueue.c~add-suspend-related-notifications-for-cpu-hotplug-cleanup +++ a/kernel/workqueue.c @@ -757,6 +757,8 @@ static int __devinit workqueue_cpu_callb struct cpu_workqueue_struct *cwq; struct workqueue_struct *wq; + action &= ~CPU_TASKS_FROZEN; + switch (action) { case CPU_LOCK_ACQUIRE: mutex_lock(&workqueue_mutex); @@ -767,7 +769,6 @@ static int __devinit workqueue_cpu_callb return NOTIFY_OK; case CPU_UP_PREPARE: - case CPU_UP_PREPARE_FROZEN: cpu_set(cpu, cpu_populated_map); } _