[Qemu-devel] [Bug 1788098] Re: Avoid migration issues with aligned 2MB THB

[Andrew Cloke]

** Also affects: qemu
   Importance: Undecided
       Status: New

** No longer affects: qemu

** Also affects: ubuntu-power-systems
   Importance: Undecided
       Status: New

** Changed in: ubuntu-power-systems
     Assignee: (unassigned) => Canonical Kernel Team (canonical-kernel-team)

** Changed in: ubuntu-power-systems
   Importance: Undecided => Critical

** Tags added: triage-g

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https://bugs.launchpad.net/bugs/1788098

Title:
  Avoid migration issues with aligned 2MB THB

Status in The Ubuntu-power-systems project:
  New
Status in linux package in Ubuntu:
  Confirmed
Status in qemu package in Ubuntu:
  Invalid
Status in linux source package in Bionic:
  Confirmed
Status in linux source package in Cosmic:
  Confirmed

Bug description:
  ------- Comment From address@hidden 2018-08-20 17:12 EDT-------
  Hi, in some environments it was observed that this qemu patch to enable THP 
made it more likely to hit guest migration issues, however the following kernel 
patch resolves those migration issues:

  
https://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc.git/commit/?h=kvm-ppc-next&id=c066fafc595eef5ae3c83ae3a8305956b8c3ef15
  KVM: PPC: Book3S HV: Use correct pagesize in kvm_unmap_radix()

  Once merged upstream, it would be good to include that change as well
  to avoid potential migration problems. Should I open a new bug for
  that or is it better to track here?

  Note Paelzer: I have not seen related migration issues myself, but it
  seems reasonable and confirmed by IBM.

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