[Openchrome-users] "Reclaim buffers locked deadlock"

[Thomas Hellström]

Thomas Hellstr?m wrote:
> Paul Bender wrote:
>
>   
>> Thomas Hellstr?m wrote:
>>  
>>
>>     
>>> Benno Schulenberg wrote:
>>>
>>>    
>>>
>>>       
>>>> Hi,
>>>>
>>>> Today I've upgraded from kernel 2.6.17 to 2.6.18, plus the latest drm from git,
>>>> and the latest libdrm.  When X is starting up there is now a pause of several
>>>> seconds before the cursor first appears, and in the kernel log there's this:
>>>>
>>>> Nov 11 23:48:31 ordesa kernel: [drm:drm_release] *ERROR* Reclaim buffers locked deadlock.
>>>> Nov 11 23:48:31 ordesa kernel: [drm:drm_release] *ERROR* This is probably a single thread having multiple
>>>> Nov 11 23:48:31 ordesa kernel: [drm:drm_release] *ERROR* DRM file descriptors open either dying or closing file descriptors
>>>> Nov 11 23:48:31 ordesa kernel: [drm:drm_release] *ERROR* while having the lock. I will not reclaim buffers.
>>>> Nov 11 23:48:31 ordesa kernel: [drm:drm_release] *ERROR* Locking context is 0x00000001
>>>> Nov 11 23:48:34 ordesa kernel: [drm:drm_release] *ERROR* Reclaim buffers locked deadlock.
>>>> Nov 11 23:48:34 ordesa kernel: [drm:drm_release] *ERROR* This is probably a single thread having multiple
>>>> Nov 11 23:48:34 ordesa kernel: [drm:drm_release] *ERROR* DRM file descriptors open either dying or closing file descriptors
>>>> Nov 11 23:48:34 ordesa kernel: [drm:drm_release] *ERROR* while having the lock. I will not reclaim buffers.
>>>> Nov 11 23:48:34 ordesa kernel: [drm:drm_release] *ERROR* Locking context is 0x00000001
>>>>
>>>> Anyone else seeing this?  Should I maybe be using the in-kernel drm instead?
>>>>
>>>> Benno
>>>>
>>>>      
>>>>
>>>>         
>>> Hi,
>>>
>>> This should be happening with AIGLX. Either someone has to fix up AIGLX 
>>> or we have to move away all drm drivers from using reclaim_buffers_locked.
>>>
>>> It might be that the latest xserver git with Dave Airlies fix to load 
>>> the system libdrm instead of the xserver built-in libdrm fixes this.
>>>
>>> The reason it doesn't hang with the old drm is a pure coincidence.
>>>
>>> /Thomas
>>>    
>>>
>>>       
>> Unfortunately, this does not appear to be the case. I grabbed libdrm 
>> 2.3.0 (as well as the drm from git corresponding to the 2.3.0 tag) and 
>> the patches from Dave Airlies' bug report. I applied the patches to the 
>> xorg-xserver from Xorg 7.2RC2 and built MiniMyth with this patched Xorg 
>> 7.2RC2. The error still occurs.
>>
>> In addition, disabling AIGLX and Composite at either compilation or run 
>> time does not appear to help.
>>
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>>
>>  
>>
>>     
> OK. I'll have a look at this next week. It should not only affect the 
> via drivers but also all drivers using reclaim_buffers_locked.
>
> What appears to be happening is the following:
> When an open file descriptor to drm is closed, drm tries to reclaim 
> allocated memory regions that belongs to the client having the file 
> open. To do that it must hold the hardware lock, and therefore it either 
> checks whether the lock belongs to the current file descriptor or waits 
> for the lock to be released. In this case, the lock is held by the X 
> server and is therefore never released, since the X server is 
> single-threaded and stuck in a system call. But the lock was taken using 
> a different file descriptor, so DRM doesn't recognize the lock as its own.
>
> So to sum up, it seems that the X server has two open files to drm. It 
> has grabbed the lock through one of them, and tries to close the other. 
> I (apparently wrongly) assumed that the "other" was AIGLX. If someone 
> can track down where this X server close operation occurs that would be 
> of great help, as I currently don't have access to any VIA systems.
>
> /Thomas
>
>   
Hmm,
I also get this problem, but only when the X server tries to launch AIGLX.
The following line in Xorg.conf's ServerLayout section gets rid of the 
message for me:

Option "AIGLX" "false"

Does anybody see the kernel message with this line in the conf file?
In that case, could you please mail your Xorg.conf and 
/var/log/Xorg.0.log file (gzipped) to the list?

Regards,
Thomas

>
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