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#261 Kernel memory leak (SLAB) Intuos Pro (PTH-651/K) in USB 3.0 port

closed-rejected
nobody
None
2015-12-04
2014-11-14
Robert Szabo
No

We seem to be having issues with our new Intuos Pro tablets when plugged into a USB 3.0 port (xhci_hcd driver) on CentOS 6.4 workstations. The kernel slab allocation for "size-64" objects keeps growing at a rate of 500 objects/s regardless if the pen/tablet is used or not. Over the course of days, tens of millions slabs get allocated eating more and more memory. I have seen workstations with 8GB of RAM allocated to 'size-64' objects. Disconnecting the wacom only stops new objects from being created, the existing ones will remain in memory.

I am not able to reproduce the issue with Intuos 5 (PTH-650) or Intuos 3 tablets or any other USB devices (mice, webcam etc.)

The CentOS 6.4 workstation is a Dell T3610 but I saw similar issues on HP Z420 workstations as well. The Kernel version is the latest available 2.6.32-431.29.2.el6.x86_64 on CentOS 6.x.

Can you please advise?

Thanks,
Robert

1 Attachments
dellt3610.tgz

Discussion

  • Robert Szabo

    Robert Szabo - 2014-11-17

    I have noticed that if I quit Xorg (therefore unload xorg-x11-wacom-drv) the allocation of size-64 objects stop but this may simply be due to the input device (/dev/input/wacom) being closed.

    I have also created a bugzilla ticket:
    https://bugzilla.redhat.com/show_bug.cgi?id=1164863

     

  • Jason Gerecke

    Jason Gerecke - 2014-11-27

    The allocation rate of 500 Hz is quite high (even while in use the tablet should only generate interrupts at ~133 Hz) so I'm not sure if our kernel driver is at fault or if there's something else in the USB stack that doesn't like the hardware. You might try compiling the [http://linuxwacom.sourceforge.net/wiki/index.php/Input-wacom input-wacom driver], though I doubt it would have an impact. You might also try recompiling the kernel with a lower CONFIG_HZ value (I believe the default is 1000 Hz) and seeing if the allocation rate drops correspondingly.

     

  • Robert Szabo

    Robert Szabo - 2014-12-11

    Thanks Jason for the answer. It turned out that we had been applying a patch to our kernels which faked the VID:PID of the Intuos Pro tablets as a supported model in the wacom driver. As you probably know best until recently Intuos Pros weren't supported but we found that they worked with the old driver. This was until we recently started plugging them in to USB 3.0 ports...
    As of CentOS 6.6 (kernel 2.6.32-504) Intuos Pros are officially supported by the wacom kernel driver and there is no memory leak either.
    Sorry for the making you chase your tail!

    Feel free to close the ticket!

    Thanks,
    Rob

     

  • Jason Gerecke

    Jason Gerecke - 2014-12-11
    • Description has changed:

    Diff:

    --- old
+++ new
@@ -1,4 +1,3 @@
-
 We seem to be having issues with our new Intuos Pro tablets when plugged into a USB 3.0 port (xhci_hcd driver) on CentOS 6.4 workstations. The kernel slab allocation for "size-64" objects keeps growing at a rate of 500 objects/s regardless if the pen/tablet is used or not. Over the course of days, tens of millions slabs get allocated eating more and more memory. I have seen workstations with 8GB of RAM allocated to 'size-64' objects. Disconnecting the wacom only stops new objects from being created, the existing ones will remain in memory.

 I am not able to reproduce the issue with Intuos 5 (PTH-650) or Intuos 3 tablets or any other USB devices (mice, webcam etc.)
    • status: new --> closed-rejected
     

  • Jason Gerecke

    Jason Gerecke - 2014-12-11

    Thanks for the update. The Intuos5 and Intuos Pro are pretty similar so I don't know why the patch you were using would have been leaking like that, but its good to know that the upstream driver isn't suffering from whatever the issue was :)