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Date:      Fri, 06 Dec 2013 16:54:57 +0100
From:      krichy@cflinux.hu
To:        Steven Hartland <killing@multiplay.co.uk>
Cc:        freebsd-fs@freebsd.org
Subject:   Re: Re: zfs deadlock
Message-ID:  <3b3b22b13d8f1cce460da46c0dd71753@cflinux.hu>
In-Reply-To: <DF23B67C7A294429B5D47D7186156BEC@multiplay.co.uk>
References:  <ce83a25c57a1d62abce7a002e8da2949@cflinux.hu> <DF23B67C7A294429B5D47D7186156BEC@multiplay.co.uk>

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Dear Steven,

Of course. But I got further now. You mentioned that is normal that zfs 
send umounts snapshots. I dont know, but this indeed causes a problem:

It is also reproducible without zfs send.
1. Have a large directory structure (just to make sure find runs long 
enough), make a snapshot of it.
# cd /mnt/pool/set/.zfs/snapshot/snap
# find .

meanwhile, on another console
# umount -f /mnt/pool/set/.zfs/snapshot/snap

will cause a panic, or such.

So effectively a regular user on a system can cause a crash.

Regards,

2013-12-06 16:50 időpontban Steven Hartland ezt írta:
> kernel compiled, installed and rebooted?
> ----- Original Message ----- From: <krichy@cflinux.hu>
> To: <smh@FreeBSD.org>
> Sent: Friday, December 06, 2013 12:17 PM
> Subject: Fwd: Re: zfs deadlock
> 
> 
>> Dear shm,
>> 
>> I've applied r258294 on top fo releng/9.2, but my test seems to 
>> trigger
>> the deadlock again.
>> 
>> Regards,
>> 
>> -------- Eredeti üzenet --------
>> Tárgy: Re: zfs deadlock
>> Dátum: 2013-12-06 13:17
>> Feladó: krichy@cflinux.hu
>> Címzett: freebsd-fs@freebsd.org
>> 
>> I've applied r258294 on top of releng/9.2, and using the attached
>> scripts parallel, the system got into a deadlock again.
>> 
>> 2013-12-06 11:35 időpontban Steven Hartland ezt írta:
>>> Thats correct it unmounts the mounted snapshot.
>>> 
>>>    Regards
>>>    Steve
>>> 
>>> ----- Original Message ----- From: <krichy@cflinux.hu>
>>> To: "Steven Hartland" <killing@multiplay.co.uk>
>>> Cc: <freebsd-fs@freebsd.org>
>>> Sent: Friday, December 06, 2013 8:50 AM
>>> Subject: Re: zfs deadlock
>>> 
>>> 
>>>> What is strange also, when a zfs send finishes, the paralell running
>>>> find command issues errors:
>>>> 
>>>> find: ./e/Chuje: No such file or directory
>>>> find: ./e/singe: No such file or directory
>>>> find: ./e/joree: No such file or directory
>>>> find: ./e/fore: No such file or directory
>>>> find: fts_read: No such file or directory
>>>> Fri Dec  6 09:46:04 CET 2013 2
>>>> 
>>>> Seems if the filesystem got unmounted meanwhile. But the script is
>>>> changed its working directory to the snapshot dir.
>>>> 
>>>> Regards,
>>>> 
>>>> 2013-12-06 09:03 időpontban krichy@cflinux.hu ezt írta:
>>>>> Dear Steven,
>>>>> 
>>>>> While I was playig with zfs, trying to reproduce the previous bug,
>>>>> accidentaly hit another one, which caused a trace I attached.
>>>>> 
>>>>> The snapshot contains directories in 2 depth, which contain files. 
>>>>> It
>>>>> was to simulate a vmail setup, with domain/user hierarchy.
>>>>> 
>>>>> I hope it is useful for someone.
>>>>> 
>>>>> I used the attached two scripts to reproduce the ZFS bug.
>>>>> 
>>>>> It definetly crashes the system, in the last 10 minutes it is the 
>>>>> 3rd
>>>>> time.
>>>>> 
>>>>> Regards,
>>>>> 2013-12-05 20:26 időpontban krichy@cflinux.hu ezt írta:
>>>>>> Dear Steven,
>>>>>> 
>>>>>> Thanks for your reply. Do you know how to reproduce the bug? 
>>>>>> Because
>>>>>> simply sending a snapshot which is mounted does not automatically
>>>>>> trigger the deadlock. Some special cases needed, or what?
>>>>>> How to prove that the patch fixes this?
>>>>>> 
>>>>>> Regards,
>>>>>> 2013-12-05 19:39 időpontban Steven Hartland ezt írta:
>>>>>>> Known issue you want:
>>>>>>> http://svnweb.freebsd.org/changeset/base/258595
>>>>>>> 
>>>>>>>    Regards
>>>>>>>    Steve
>>>>>>> 
>>>>>>> ----- Original Message ----- From: "Richard Kojedzinszky"
>>>>>>> <krichy@cflinux.hu>
>>>>>>> To: <freebsd-fs@freebsd.org>
>>>>>>> Sent: Thursday, December 05, 2013 2:56 PM
>>>>>>> Subject: zfs deadlock
>>>>>>> 
>>>>>>> 
>>>>>>>> Dear fs devs,
>>>>>>>> 
>>>>>>>> We have a freenas server, which is basicaly a freebsd. I was
>>>>>>>> trying to look at snapshots using ls .zfs/snapshot/.
>>>>>>>> 
>>>>>>>> When I issued it, the system entered a deadlock. An NFSD was
>>>>>>>> running, a zfs send was running when I issued the command.
>>>>>>>> 
>>>>>>>> I attached to command outputs while the system was in a deadlock
>>>>>>>> state. I tried to issue
>>>>>>>> # reboot -q
>>>>>>>> But that did not restart the system. After a while (5-10 
>>>>>>>> minutes)
>>>>>>>> the system rebooted, I dont know if the deadman caused that.
>>>>>>>> 
>>>>>>>> Now the system is up and running.
>>>>>>>> 
>>>>>>>> It is basically a freebsd 9.2 kernel.
>>>>>>>> 
>>>>>>>> Do someone has a clue?
>>>>>>>> 
>>>>>>>> Kojedzinszky Richard
>>>>>>> 
>>>>>>> 
>>>>>>> --------------------------------------------------------------------------------
>>>>>>> 
>>>>>>> 
>>>>>>>> _______________________________________________
>>>>>>>> freebsd-fs@freebsd.org mailing list
>>>>>>>> http://lists.freebsd.org/mailman/listinfo/freebsd-fs
>>>>>>>> To unsubscribe, send any mail to
>>>>>>>> "freebsd-fs-unsubscribe@freebsd.org"
>>>>>>> 
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