Re: [Xenomai-help] Problems with rt pipes after upgrade

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

On 05/14/2011 12:39 AM, Thomas Schaefer wrote:
> 
> Hello,
> 
> ----------------------------------------
>> Subject: Re: [Xenomai-help] Problems with rt pipes after upgrade
>> From: rpm@xenomai.org
>> To: thomas_schaefer_canada@domain.hid
>> CC: xenomai@xenomai.org
>> Date: Fri, 13 May 2011 12:26:26 +0200
>>
>> On Wed, 2011-05-11 at 07:46 -0700, Thomas Schaefer wrote:
>>>
>>> Hi,
>>>
>>> we are currently running an earlier version of Xenomai (2.5.3) on a Quad core Xeon with kernel 2.6.31.8(X86_64).
>>> I was looking into upgrading to the latest Xenomai version from the git head and kernel 2.6.37.6.
>>> Everything seems to work well except creating rt_pipes in the kernel driver.
>>> First I thought this is a problem with our PCIe driver but I see the same problem when loading xeno_klat.
>>>
>>> # modprobe xeno_klat
>>> [ 70.511784] ------------[ cut here ]------------
>>> [ 70.516422] WARNING: at fs/proc/generic.c:860 remove_proc_entry+0x25b/0x260()
>>> [ 70.523556] Hardware name: D-Mitri
>>> [ 70.526960] remove_proc_entry: removing non-empty directory 'native/pipes', leaking at least 'klat_pipe'
>>> [ 70.536433] Modules linked in: xeno_klat bonding [last unloaded: scsi_wait_scan]
>>> [ 70.545910] Pid: 296, comm: kworker/1:1 Not tainted 2.6.37.6 #4
>>> [ 70.551834] Call Trace:
>>> [ 70.554291] [] ? warn_slowpath_common+0x7b/0xc0
>>> [ 70.560484] [] ? warn_slowpath_fmt+0x45/0x50
>>> [ 70.566402] [] ? __xlate_proc_name+0x35/0xd0
>>> [ 70.572330] [] ? remove_proc_entry+0x25b/0x260
>>> [ 70.578434] [] ? registry_proc_callback+0x4b5/0x5c0
>>> [ 70.584963] [] ? registry_proc_callback+0x0/0x5c0
>>> [ 70.591330] [] ? process_one_work+0x107/0x3c0
>>> [ 70.597351] [] ? worker_thread+0x14c/0x410
>>> [ 70.603106] [] ? worker_thread+0x0/0x410
>>> [ 70.608678] [] ? kthread+0x95/0xa0
>>> [ 70.613758] [] ? kernel_thread_helper+0x4/0x10
>>> [ 70.619857] [] ? kthread+0x0/0xa0
>>> [ 70.624840] [] ? kernel_thread_helper+0x0/0x10
>>> [ 70.630941] ---[ end trace 793ec26c5b485748 ]---
>>>
>>>
>>> I would appreciate if someone could point me in the right direction of the possible cause.
>>
>> This very much looks like a race in the registry support. We have to
>> resync registry object deletion done from primary mode with the linux
>> kernel actually doing the work for us (via /procfs), and somehow, we
>> don't do this right. This is not a critical issue and will likely not
>> break your platform, but this is still quite ugly, and requires a fix.
>>
>> Could you give us some hints about how to reproduce this easily? TIA,
>>
>  
> I used VBox and installed a very basic Debian squeeze with the netinst.iso.
> Installed our kernel into it from the debian package I created and copied xeno_klat.ko to it.
> Running insmod xeno_klat.ko shows the same symptom.

xeno_klat insmods here without any problem. You probably have some
debugging option enabled. Could your post the .config of the kernel you use?

-- 
                                                                Gilles.