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[dronus <1447052@xxxxxxxxxxxxxxxxxx>]

I tried the kernel 4.0.0-040000rc7-generic at a newer machine sporting
Ubuntu 14.04.

It was hard to get it swapping as it some applications seems to be
better now on itself, for example the newer Gimp seems to have a
sophisticated virtual image memory by itself, so it almost never causes
swapping anymore. However, using some applications under my development,
I could trigger swap easily, like with the "Remesh"-Modifier of Blender.
Swapping still renders the system unresponsive. On the other hand, I was
able to recover from unusable state in reasonable time. I do not know if
the newer kernel does anything smarter, or the test condition is not
repeatable enough.

I will try to find an example every user could repeat that would
reliable lead to unresponsiveness.

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https://bugs.launchpad.net/bugs/1447052

Title:
  System should never drive into unresponsive swapping by naive end-user
  handling operations

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  Even for the newest Ubuntu, even on memory rich high end systems
  sporting fast SSD drives, the system can be driven into long time
  swapping state with unresponsiveness (jerky mouse movements or no
  movement at all, no reaction to clicks and keypresses) easily by naive
  everyday operations. The state may last for hours depending on the
  applications behaviour, only workaround is to pull the plug. This is
  akward. Many users often have a quite messy desktop with several
  applications opened at once, hence a large risk of data loss if the
  system has to be restarted in an unresponsive condition.

  This should not be blamed on bad behaveing applications alone, as
  there are a lot of naive applications around, and it is not the right
  of some desktop application to bring down the whole system.

  Some example "mistakes" a "naive" user may do, the list may be easily
  extended endless:

  -Open an oversized image or a long list of images in Gimp
  -Mark an entire column in Libreoffice Calc and fill down with some complex formula
  -Open a long collection of PDFs at once
  -Accidently open some large ASCII database- or log file with Libreoffice Writer
  -Pull up interactive sliders in Blender related to detail refinements 
  -...

  
  I guess it is not easy to work around, but the current state is unbearable in my opinion.

  This may also have security implications, as unresponsiveness prevent
  manual entering of screen locks, shotdown or standby, which may leave
  the machine unlocked, if the user leaves the unresponsive machine and
  it then recovers.

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