Re: [uml-devel] Issues with a rather unusual configured NFS server

["Toralf Förster" <toralf.foerster@gmx.de>]

On 09/01/2013 11:15 PM, Richard Weinberger wrote:
> Am 01.09.2013 18:09, schrieb Toralf Förster:
>> On 08/30/2013 04:36 PM, Richard Weinberger wrote:
>>> Am 30.08.2013 16:10, schrieb Toralf Förster:
>>>> On 08/29/2013 03:30 PM, J. Bruce Fields wrote:
>>>>> On Thu, Aug 29, 2013 at 11:57:45AM +0200, richard -rw- weinberger wrote:
>>>>>> On Wed, Aug 28, 2013 at 7:21 PM, Toralf Förster <toralf.foerster@gmx.de> wrote:
>>>>>>> On 08/27/2013 08:06 PM, J. Bruce Fields wrote:
>>>>>>>> On Tue, Aug 13, 2013 at 05:53:14PM -0400, bfields wrote:
>>>>>>>>> On Mon, Aug 12, 2013 at 04:36:40PM +0200, Jan Kara wrote:
>>>>>>>>>> On Sun 11-08-13 11:48:49, Toralf Förster wrote:
>>>>>>>>>>> so that the server either crashes (if it is a user mode linux image) or at least its reboot functionality got broken
>>>>>>>>>>> - if the NFS server is hammered with scary NFS calls using a fuzzy tool running at a remote NFS client under a non-privileged user id.
>>>>>>>>>>>
>>>>>>>>>>> It can re reproduced, if
>>>>>>>>>>>    - the NFS share is an EXT3 or EXT4 directory
>>>>>>>>>>>    - and it is created at file located at tempfs and mounted via loop device
>>>>>>>>>>>    - and the NFS server is forced to umount the NFS share
>>>>>>>>>>>    - and the server forced to restart the NSF service afterwards
>>>>>>>>>>>    - and trinity is used
>>>>>>>>>>>
>>>>>>>>>>> I could find a scenario for an automated bisect. 2 times it brought this commit
>>>>>>>>>>> commit 68a3396178e6688ad7367202cdf0af8ed03c8727
>>>>>>>>>>> Author: J. Bruce Fields <bfields@redhat.com>
>>>>>>>>>>> Date:   Thu Mar 21 11:21:50 2013 -0400
>>>>>>>>>>>
>>>>>>>>>>>     nfsd4: shut down more of delegation earlier
>>>>>>>>>
>>>>>>>>> Thanks for the report.  I think I see the problem--after this commit
>>>>>>>>> nfs4_set_delegation() failures result in nfs4_put_delegation being
>>>>>>>>> called, but nfs4_put_delegation doesn't free the nfs4_file that has
>>>>>>>>> already been set by alloc_init_deleg().
>>>>>>>>>
>>>>>>>>> Let me think about how to fix that....
>>>>>>>>
>>>>>>>> Sorry for the slow response--can you check whether this fixes the
>>>>>>>> problem?
>>>>>>>>
>>>>>>> Yes.
>>>>>>>
>>>>>>> With the attached patch the problem can't be reproduced any longer with
>>>>>>> the prepared test case and current git kernels.
>>>>>>
>>>>>> BTW: Is nobody else fuzz testing NFS?
>>>>>
>>>>> I don't know.  Toralf's reports are the only ones I recall off the top
>>>>> of my head, but I may have forgotten others.
>>>>>
>>>>
>>>> well, 7255e71 and 3c50ba8 I'd say.
>>>>
>>>>>> Or are these bugs just more likely to hit on UML?
>>>>
>>>> This definitely not. I observed at a real system EXT4 corruptions/
>>>> issues but reported them to the EXT4 mailing list.
>>>> It just took me a longer time to figure out a reliable configuration
>>>> with 2 UML machiens to automatic bisect it.
>>>>
>>>>
>>>>> That's also possible.
>>>>>
>>>>>> This is not the first NFS issue found by Toralf using UML and Trinity.
>>>>>
>>>>> Yep.  The testing is definitely appreciated.
>>>>
>>>> Thx - in the mean while although my UML bisect scripts are working fine
>>>> and trinity is stable enough even in UML environments to be trust worth.
>>>
>>> That's good to know.
>>> Thanks you and trinity we got rid of some nasty UML bugs.
>>
>> yeah, but there's (among others) one of them still in the wild:
>> If I start an UML and resize the terminal (KDE Konsole) during the boot
>> phase then it just crashes sometimes.
> 
> Does the attached patch fix the problem?
> 
oh yes
And I do have the feeling that the UML start phase till the Gentoo
openrc line is seen is speed up too :-)

> Thanks,
> //richard
> 


-- 
MfG/Sincerely
Toralf Förster
pgp finger print: 7B1A 07F4 EC82 0F90 D4C2 8936 872A E508 7DB6 9DA3

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