Leonardo, can you elaborate on the 'other possible issues'? We're hesitant to pull 18 patches into a stable kernel under the assumption that they *might* fix some *potential* issues, without clear evidence. If you can test the single-patch kernel and report back that there are still issues then that's a much stronger case for the other patches.
Commit 'KVM: PPC: Book3S HV: Avoid crash from THP collapse during radix page fault' that you're asking for requires all these additional backports to apply cleanly. Which makes me wonder if we're not actually introducing a problem with these backports just to fix it again later. Not saying that's the case, just wondering... Also, the following seem to be totally unrelated and unnecessary: - KVM: PPC: Remove unused kvm_unmap_hva callback - powerpc/mm/radix: Remove unused code While looking through the patches I also noticed that the following is the second patch of a series of 11 but it's the only one from the series that you're backporting. - powerpc/kvm: Switch kvm pmd allocator to custom allocator Its commit message mentions subsequent patches of that series so I'm wondering why we need/want only this single patch?? Remember that we have to support this kernel for years and years to come so we only want to backport the absolute necessary. Lastly and FYI, the following is the minimal subset of your patches that all cherry-pick cleanly: - KVM: PPC: Book3S HV: Avoid crash from THP collapse during radix page fault - KVM: PPC: Book3S HV: Don't use compound_order to determine host mapping size - KVM: PPC: Book3S HV: Use correct pagesize in kvm_unmap_radix() - KVM: PPC: Book3S HV: radix: Refine IO region partition scope attributes - KVM: PPC: Book3S HV: Use __gfn_to_pfn_memslot() in page fault handler - KVM: PPC: Book3S HV: Handle 1GB pages in radix page fault handler - KVM: PPC: Book3S HV: Streamline setting of reference and change bits - KVM: PPC: Book3S HV: Radix page fault handler optimizations Please provide some context why we need all the above (and potentially more). -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1788098 Title: Avoid migration issues with aligned 2MB THB Status in The Ubuntu-power-systems project: Incomplete Status in linux package in Ubuntu: Incomplete Status in qemu package in Ubuntu: Invalid Status in linux source package in Bionic: Incomplete 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 jhop...@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. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-power-systems/+bug/1788098/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
