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Date: Tue, 15 Oct 2013 10:42:30 +0900
From: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
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To: Greg KH <gregkh@linuxfoundation.org>
CC: <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>, <toshi.kani@hp.com>,
        <sjenning@linux.vnet.ibm.com>
Subject: Re: [PATCH] Release device_hotplug_lock when store_mem_state returns
 EINVAL
References: <52579C69.1080304@jp.fujitsu.com> <20131011155454.GA32305@kroah.com>
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Hi Greg,

(2013/10/12 0:54), Greg KH wrote:
> On Fri, Oct 11, 2013 at 03:36:25PM +0900, Yasuaki Ishimatsu wrote:
>> When inserting a wrong value to /sys/devices/system/memory/memoryX/state file,
>> following messages are shown. And device_hotplug_lock is never released.
>>
>> ================================================
>> [ BUG: lock held when returning to user space! ]
>> 3.12.0-rc4-debug+ #3 Tainted: G        W
>> ------------------------------------------------
>> bash/6442 is leaving the kernel with locks still held!
>> 1 lock held by bash/6442:
>>   #0:  (device_hotplug_lock){+.+.+.}, at: [<ffffffff8146cbb5>] lock_device_hotplug_sysfs+0x15/0x50
>>
>> This issue was introdued by commit fa2be40 (drivers: base: use standard
>> device online/offline for state change).
>>
>> This patch releases device_hotplug_lcok when store_mem_state returns EINVAL.
>>
>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>> CC: Toshi Kani <toshi.kani@hp.com>
>> CC: Seth Jennings <sjenning@linux.vnet.ibm.com>
>> CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>
> Is this needed in 3.12-final, and possibly older kernel releases as well
> (3.10, 3.11, etc.)?  Or is it ok for 3.13?

The patch is needed in 3.12 because this problem has occurred since 3.12-rc1.

Thanks,
Yasuaki Ishimatsu

>
> thanks,
>
> greg k-h
>


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