From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sebastian Hetze <s.hetze@linux-ag.com>
Subject: Re: syscall rmdir hangs with autofs
Date: Mon, 19 Jul 2010 15:45:58 +0200
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Cc: Sebastian Hetze <s.hetze@linux-ag.com>, kvm@vger.kernel.org
To: Avi Kivity <avi@redhat.com>
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On Mon, Jul 19, 2010 at 04:09:12PM +0300, Avi Kivity wrote:
> On 07/19/2010 03:48 PM, Sebastian Hetze wrote:
>>
>>> Looks like a false alarm then.  The rmdir is waiting for the mount to
>>> flush everything to disk, which is slow and takes a while.
>>>
>>> Does it return eventually?
>>>      
>> No, it does not return within hours (>10). And the problem occurs only
>> once in a while although the system is busy every day (and night)
>> and automount is mounting/expiring frequently.
>>
>> I would expect the "/bin/umount dir" process (which is forked by
>> automount if I read the code correctly) to return only after the flush
>> is complete. So I expect the rmdir being called afterwards on an plain
>> empty directory.
>>
>> BTW: the mount is just a bind mount, so no flush should be necessary
>> anyway.
>>    
>
> It looks like VFS breakage.  Does this happen with older guest kernels?

currently I can confirm this problem with 2.6.31-22-generic-pae back to
2.6.31-16-generic-pae. What guest kernel version would you suggest?