2013-07-03 14:07:42

by Lei Wen

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Subject: task kworker/u:0 blocked for more than 120 seconds

Hi list,

I recently find a strange issue over 3.4 kernel.
The scenario is doing the hotplug test over ARM platfrom, and when the
hotplugged
out cpu1 want to get back in again, seems it stuck at cpu_stop_cpu_callback.

The task backtrace is as below:
PID: 21749 TASK: d194b300 CPU: 0 COMMAND: "kworker/u:0"
#0 [<c05d6ff0>] (__schedule) from [<c05d5604>]
#1 [<c05d5604>] (schedule_timeout) from [<c05d6a34>]
#2 [<c05d6a34>] (wait_for_common) from [<c01543c8>]
#3 [<c01543c8>] (kthread_create_on_node) from [<c05cf524>]
#4 [<c05cf524>] (cpu_stop_cpu_callback) from [<c0159664>]
#5 [<c0159664>] (notifier_call_chain) from [<c0139a84>]
#6 [<c0139a84>] (__cpu_notify) from [<c05cdda4>]
#7 [<c05cdda4>] (_cpu_up) from [<c05cdeb0>]
#8 [<c05cdeb0>] (cpu_up) from [<c05c3bf8>]
#9 [<c05c3bf8>] (hotplug_timer) from [<c014fe24>]
#10 [<c014fe24>] (process_one_work) from [<c0150240>]
#11 [<c0150240>] (worker_thread) from [<c01541b4>]
#12 [<c01541b4>] (kthread) from [<c0113ed8>]

Since I have full memory dump, and could do further analysis, do you
have any idea
that what kind of info need to provide to get it root caused?

Thanks,
Lei