ubuntu-x-swat team mailing list archive

[Tormod Volden <bugpost.tormod@xxxxxxxxx>]

** Description changed:

  [Problem]
  Memory leak.  Fix to glx 1.4 backport did not deallocate gem objects properly.
  
  [Background]
  Red Hat backported glx 1.3 and 1.4 support from xserver 1.8.  These patches were taken by Debian as patches 03_fedora_glx_versioning.diff and 04_fedora_glx14-swrast.diff, and so Ubuntu took them in order to remain in sync with Debian.  Other distros using xserver 1.7 have likewise adopted these backports.
  
  Subsequent testing by Ubuntu identified an xserver crash that occurs
  with these patches enabled when closing Clutter apps.  A partial fix was
  implemented in Ubuntu based on upstream work, and the issue believed
  solved, but further testing has shown that a slow memory leak is
  present, causing issues such as described below, which can result in
  system instability after a day or two of uptime (depending on memory
  quantity and usage).  Distros that don't include support for Clutter
  obviously won't see the bugs.
  
  Following these findings, Debian has dropped the glx patches.  Ubuntu is
  evaluating fixing the patches vs. following Debian's approach, being
  mindful of any userspace apps that may have come to depend on glx
  1.3/1.4 functionality.
  
  [Original Report]
  There has been some buzz the last days about excessive swapping and OOM conditions. It can seem like the kernel memory use is increasing since the user processes seem not to grow unusually.
  
  /sys/kernel/debug/dri/0/gem_objects shows that the GEM object bytes
  number is increasing. One way to reproduce, is this:
  
- $ for t in `seq 1 10`; do eog /usr/share/backgrounds ; echo `grep "object bytes" /sys/kernel/debug/dri/0/gem_objects` `ps --noheaders ocomm,vsz,rss ($pidof X)`; done
+ $ for t in `seq 1 10`; do eog /usr/share/backgrounds ; echo `grep "object bytes" /sys/kernel/debug/dri/0/gem_objects` `ps --noheaders ocomm,vsz,rss $(pidof X)`; done
  142376960 object bytes Xorg 25812 15372
  145907712 object bytes Xorg 25812 15372
  150458368 object bytes Xorg 25812 15372
  154816512 object bytes Xorg 25812 15372
  159244288 object bytes Xorg 25812 15372
  163721216 object bytes Xorg 25812 15372
  168148992 object bytes Xorg 25812 15372
  172699648 object bytes Xorg 25812 15372
  177152000 object bytes Xorg 25812 15372
  181530624 object bytes Xorg 25812 15372
  
  It shows that the Xorg process is not growing, but gem objects are. Similarly counting and summing objects show there are gem objects adding up (with refcount 2) but not disappearing again when the application closes:
   awk '/name/{ i++; s+= $4 } END{print i " " s}' /sys/kernel/debug/dri/0/gem_names
  
  These issues have been seen on intel and ati, with the lucid kernel as
  well as the mainline 2.6.34 snapshot.
  
  ProblemType: Bug
  DistroRelease: Ubuntu 10.04
  Package: xorg 1:7.5+5ubuntu1
  Uname: Linux 2.6.34-999-generic i686
  Architecture: i386
  Date: Sun Apr 18 15:59:21 2010
  ProcEnviron:
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: xorg
  system:
   distro:             Ubuntu
   codename:           lucid
   architecture:       i686
   kernel:             2.6.34-999-generic

-- 
[KMS] gem objects not deallocated
https://bugs.launchpad.net/bugs/565981
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