[Kernel-packages] [Bug 1587078] Re: OOM in guest Ubuntu with inflated balloon

2016-06-07 Thread Joseph Salisbury 
You say this bug affects Ubuntu 14.10.  Does it not affect prior
releases such as 14.04(Xenial)?

** Changed in: linux (Ubuntu)
   Importance: Undecided => Medium

** Changed in: linux (Ubuntu)
   Status: Incomplete => Triaged

** Tags added: kernel-da-key yakkety

** Changed in: linux (Ubuntu)
 Assignee: (unassigned) => Joseph Salisbury (jsalisbury)

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Title:
  OOM in guest Ubuntu with inflated balloon

Status in linux package in Ubuntu:
  Triaged

Bug description:
  There is QEMU/KVM and a Linux OS running inside the guest.
  Inside the Linux guest a balloon consumes memory in accordance with
  commands performed on the host side in QEMU. Rapid increases of memory 
consumption
  inside the guest may end up with guest OOMs
  since memory locked by balloon couldn’t be returned to the guest OS/vm in 
time.

  The problem is addressed in mainstream Linux with the following
  patchset:

  commit 5a10b7dbf904bfe01bb9fcc6298f7df09eed77d5
  Author: Raushaniya Maksudova 
  Date:   Mon Nov 10 09:36:29 2014 +1030
  virtio_balloon: free some memory from balloon on OOM

  Excessive virtio_balloon inflation can cause invocation of OOM-killer,
  when Linux is under severe memory pressure. Various mechanisms are
  responsible for correct virtio_balloon memory management. Nevertheless
  it is often the case that these control tools does not have enough time
  to react on fast changing memory load. As a result OS runs out of memory
  and invokes OOM-killer. The balancing of memory by use of the virtio
  balloon should not cause the termination of processes while there are
  pages in the balloon. Now there is no way for virtio balloon driver to
  free some memory at the last moment before some process will be get
  killed by OOM-killer.

  This does not provide a security breach as balloon itself is running
  inside guest OS and is working in the cooperation with the host. Thus
  some improvements from guest side should be considered as normal.

  To solve the problem, introduce a virtio_balloon callback which is
  expected to be called from the oom notifier call chain in out_of_memory()
  function. If virtio balloon could release some memory, it will make
  the system to return and retry the allocation that forced the out of
  memory killer to run.

  Allocate virtio  feature bit for this: it is not set by default,
  the the guest will not deflate virtio balloon on OOM without explicit
  permission from host.

  Signed-off-by: Raushaniya Maksudova 
  Signed-off-by: Denis V. Lunev 
  Acked-by: Michael S. Tsirkin 
  Signed-off-by: Rusty Russell 

  commit 1fd9c67203af91977bf3b964ff3744cf74fc6f3f
  Author: Raushaniya Maksudova 
  Date:   Mon Nov 10 09:35:29 2014 +1030

  virtio_balloon: return the amount of freed memory from
  leak_balloon()

  This value would be useful in the next patch to provide the amount of
  the freed memory for OOM killer.

  Signed-off-by: Raushaniya Maksudova 
  Signed-off-by: Denis V. Lunev 
  CC: Rusty Russell 
  CC: Michael S. Tsirkin 
  Signed-off-by: Rusty Russell 

  The problem is present in Ubuntu 14.10

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[Kernel-packages] [Bug 1587078] Re: OOM in guest Ubuntu with inflated balloon

2016-05-30 Thread Colin Watson 
** Project changed: ubuntu-ubuntu-server => linux (Ubuntu)

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https://bugs.launchpad.net/bugs/1587078

Title:
  OOM in guest Ubuntu with inflated balloon

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  There is QEMU/KVM and a Linux OS running inside the guest.
  Inside the Linux guest a balloon consumes memory in accordance with
  commands performed on the host side in QEMU. Rapid increases of memory 
consumption
  inside the guest may end up with guest OOMs
  since memory locked by balloon couldn’t be returned to the guest OS/vm in 
time.

  The problem is addressed in mainstream Linux with the following
  patchset:

  commit 5a10b7dbf904bfe01bb9fcc6298f7df09eed77d5
  Author: Raushaniya Maksudova 
  Date:   Mon Nov 10 09:36:29 2014 +1030
  virtio_balloon: free some memory from balloon on OOM

  Excessive virtio_balloon inflation can cause invocation of OOM-killer,
  when Linux is under severe memory pressure. Various mechanisms are
  responsible for correct virtio_balloon memory management. Nevertheless
  it is often the case that these control tools does not have enough time
  to react on fast changing memory load. As a result OS runs out of memory
  and invokes OOM-killer. The balancing of memory by use of the virtio
  balloon should not cause the termination of processes while there are
  pages in the balloon. Now there is no way for virtio balloon driver to
  free some memory at the last moment before some process will be get
  killed by OOM-killer.

  This does not provide a security breach as balloon itself is running
  inside guest OS and is working in the cooperation with the host. Thus
  some improvements from guest side should be considered as normal.

  To solve the problem, introduce a virtio_balloon callback which is
  expected to be called from the oom notifier call chain in out_of_memory()
  function. If virtio balloon could release some memory, it will make
  the system to return and retry the allocation that forced the out of
  memory killer to run.

  Allocate virtio  feature bit for this: it is not set by default,
  the the guest will not deflate virtio balloon on OOM without explicit
  permission from host.

  Signed-off-by: Raushaniya Maksudova 
  Signed-off-by: Denis V. Lunev 
  Acked-by: Michael S. Tsirkin 
  Signed-off-by: Rusty Russell 

  commit 1fd9c67203af91977bf3b964ff3744cf74fc6f3f
  Author: Raushaniya Maksudova 
  Date:   Mon Nov 10 09:35:29 2014 +1030

  virtio_balloon: return the amount of freed memory from
  leak_balloon()

  This value would be useful in the next patch to provide the amount of
  the freed memory for OOM killer.

  Signed-off-by: Raushaniya Maksudova 
  Signed-off-by: Denis V. Lunev 
  CC: Rusty Russell 
  CC: Michael S. Tsirkin 
  Signed-off-by: Rusty Russell 

  The problem is present in Ubuntu 14.10

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1587078/+subscriptions

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