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Date: Fri, 28 May 2010 14:46:59 +0800
From: =?utf-8?Q?Am=C3=A9rico?= Wang <xiyou.wangcong@gmail.com>
To: Tejun Heo <tj@kernel.org>
Cc: =?utf-8?Q?Am=C3=A9rico?= Wang <xiyou.wangcong@gmail.com>,
       David Howells <dhowells@redhat.com>, davem@davemloft.net,
       jens.axboe@oracle.com, linux-kernel@vger.kernel.org, torvalds@osdl.org,
       viro@ZenIV.linux.org.uk, akpm@linux-foundation.org
Subject: Re: [PATCH] fs: run emergency remount on dedicated workqueue
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On Thu, May 27, 2010 at 07:03:11PM +0200, Tejun Heo wrote:
>On 05/27/2010 04:59 PM, Américo Wang wrote:
>> On Thu, May 27, 2010 at 11:57:23AM +0200, Tejun Heo wrote:
>>> Commit fa4b9074cd8428958c2adf9dc0c831f46e27c193 made s_umount depend
>>> on keventd; however, emergency remount schedules works to keventd
>>> which grabs s_umount creating a circular dependency.  Run emergency
>>> remount on a separate workqueue to break it.
>>>
>> 
>> I have a stupid question, why using workqueue instead of
>> calling do_remount_sb() directly in emergency_remount()?
>> Avoid blocking emergency_remount()?
>
>Umm... because it's called from interrupt handler?  Right?

Ah, this is true, sysrq can be both triggered by keyboard and
/proc/sysrq-trigger.

Thanks!