Re: Hang running fs_mark

[Ric Wheeler <rwheeler@redhat.com>]

Chris Mason wrote:
> On Thu, 2008-09-25 at 14:34 -0400, Josef Bacik wrote:
>   
>> On Thu, Sep 25, 2008 at 02:37:02PM -0400, Chris Mason wrote:
>>     
>>> On Thu, 2008-09-25 at 13:56 -0400, Josef Bacik wrote:
>>>       
>>>> Hello,
>>>>
>>>> Reporting this on behalf of ric.  He was running the following fs_mark command
>>>>
>>>> ./fs_mark -d /mnt/test -s 20480 -D 64 -t 8 -F
>>>>
>>>> Seems it hung and wasn't making any progress.  He managed to get some sysrq-t,
>>>> which is at http://people.redhat.com/jwhiter/fs-mark-hang.txt towards the bottom
>>>> of the document.  He could ctrl+c and unmount the fs so its not a hard hang.
>>>> Looks like we've just locked up behind a page lock somewhere.  I have to run off
>>>> to class so I can't look into it too deeply so throwing this out there hoping
>>>> somebody else figures it out :).  Thanks,
>>>>         
>>> Which kernel was this?
>>>       
>
>   
>> Its 2.6.25.14-108.fc9.x86_64 and its kernel-unstable since yesterday I think he
>> said, its just shy whatever patches you've pushed into git recently, it has
>> yan's backref work plus a few other fixes.  Thanks,
>>
>>     
>
> Well, the trace is strange because it looks like everyone is waiting on
> IO.  Any chance once of the procs was spinning in system time?
>
> -chris
>
>   

It actually cleaned up very nicely after I killed the fs_mark processes 
& unmounted the btrfs file system. Before doing that, the box was 
sluggish and had the feeling of a system with something that might have 
been spinning (but that is just an observation, not measured in any 
strict sense).

ric