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

** Attachment added: "patches.tar.gz"
https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1788098/+attachment/5242393/+files/patches.tar.gz

** Changed in: linux (Ubuntu Bionic)
Status: New => Confirmed

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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:
Confirmed
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:
Invalid

Bug description:
FYI: This blocks bug 1781526 - once this one here is resolved we can
go on with SRU considerations for 1781526

------- Comment From jhopper@us.ibm.com 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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