zfs deadlock

Fri Dec 6 15:59:09 UTC 2013

So maybe the force flag is too strict. Under linux the snapshots remains 
mounted after a send.

2013-12-06 16:54 időpontban krichy at cflinux.hu ezt írta:
> 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 at cflinux.hu>
>> To: <smh at 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 at cflinux.hu
>>> Címzett: freebsd-fs at 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 at cflinux.hu>
>>>> To: "Steven Hartland" <killing at multiplay.co.uk>
>>>> Cc: <freebsd-fs at 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 at 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 at 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 at cflinux.hu>
>>>>>>>> To: <freebsd-fs at 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
>>>>>>>> 
>>>>>>>> 
>>>>>>>> --------------------------------------------------------------------------------
>>>>>>>> 
>>>>>>>> 
>>>>>>>>> _______________________________________________
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>>>>>>>>> http://lists.freebsd.org/mailman/listinfo/freebsd-fs
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>>>>>>>>> "freebsd-fs-unsubscribe at freebsd.org"
>>>>>>>> 
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