The latest kernel from yakkety-proposed does not appear to fix the problem. Note that I did test it on Xenial, not Yakkety, because I do not have an easy way to reproduce the bug that excercises rate-limited printk on Yakkety.
I made sure that the proposed kernel was used by comparing what is getting installed on Yakkety vs Xenial: On Yakkety ========== $ sudo apt-get install -y linux-image-generic/yakkety-proposed Selected version '4.8.0.44.56' (Ubuntu:16.10/yakkety-proposed [ppc64el]) for 'linux-image-generic' The following additional packages will be installed: crda iw libnl-3-200 libnl-genl-3-200 linux-firmware linux-image-4.8.0-44-generic linux-image-extra-4.8.0-44-generic wireless-regdb Suggested packages: fdutils linux-doc-4.8.0 | linux-source-4.8.0 linux-tools linux-headers-4.8.0-44-generic The following NEW packages will be installed: crda iw libnl-3-200 libnl-genl-3-200 linux-firmware linux-image-4.8.0-44-generic linux-image-extra-4.8.0-44-generic linux-image-generic wireless-regdb # uname -a Linux mmedvede2-test-ratelimit-pkvmci836 4.8.0-44-generic #47-Ubuntu SMP Wed Mar 22 14:27:02 UTC 2017 ppc64le ppc64le ppc64le GNU/Linux On Xenial ========= $ sudo apt-get install -y linux-image-generic/yakkety-proposed Selected version '4.8.0.44.56' (Ubuntu:16.10/yakkety-proposed [ppc64el]) for 'linux-image-generic' The following additional packages will be installed: linux-image-4.8.0-44-generic linux-image-extra-4.8.0-44-generic Suggested packages: fdutils linux-doc-4.8.0 | linux-source-4.8.0 linux-tools linux-headers-4.8.0-44-generic The following NEW packages will be installed: linux-image-4.8.0-44-generic linux-image-extra-4.8.0-44-generic The following packages will be upgraded: linux-image-generic $ uname -a Linux mmedvede-test-ratelimit-pkvmci8361 4.8.0-44-generic #47-Ubuntu SMP Wed Mar 22 14:27:02 UTC 2017 ppc64le ppc64le ppc64le GNU/Linux And I was able to reproduce the printk spam on Xenial with the proposed kernel. Did the fix actually get into 4.8.0.44.56? -- 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/1667416 Title: PowerNV: No rate limit for kernel error "KVM can't copy data from" Status in linux package in Ubuntu: Fix Released Status in linux source package in Yakkety: Fix Committed Bug description: == Comment: #0 - MIKHAIL S. MEDVEDEV <mmedv...@us.ibm.com> - 2017-02-03 14:40:58 == ---Problem Description--- I am experiencing a problem with KVM on Power with a symptom of "KVM can't copy data" message being spammed to kern.log at about 100000 messages a second. Apart from original problem that triggers the error, the printk is a problem on its own. System might run out of space for logs, and would have high CPU load caused by journald. This bug is to address an absence of rate limiter on printk at https://github.com/torvalds/linux/blob/f64e8084c94bb0449177364856d8117e2f14c4c0/arch/powerpc/kvm/book3s_64_mmu.c#L268 Maybe wrapping the printk in printk_ratelimit() is all that is required? if(printk_ratelimit()){ printk("KVM can't copy"); } Contact Information = Mikhail Medvedev / mmedv...@us.ibm.com, Rafael Folco / rfo...@br.ibm.com ---uname output--- 4.8.0-34-generic #36~16.04.1-Ubuntu SMP Wed Dec 21 18:53:20 UTC 2016 ppc64le ppc64le ppc64le GNU/Linux Machine Type = KVM guest on P8 8247 21L ---Debugger--- A debugger is not configured ---Steps to Reproduce--- 1. Deploy OpenStack with devstack 2. Run simultaneously between 4 and 6 instances of a script that - boots a VM (openstack server create) - immediately creates the backup of the VM (openstack server backup create) This is not a very good way to reproduce it. I am still unable to reproduce the problem just by using libvirt and qemu. == Comment: #5 - VIPIN K. PARASHAR <vipar...@in.ibm.com> - 2017-02-07 09:42:31 == From kernel logs =========== [852719.001593] KVM can't copy data from 0x3fff86683c80! [852719.001614] KVM can't copy data from 0x3fff86683c80! [852719.001617] KVM can't copy data from 0x3fff66a83c80! [852719.001624] KVM can't copy data from 0x3fff86683c80! [852719.001634] KVM can't copy data from 0x3fff86683c80! [852719.001637] KVM can't copy data from 0x3fff66a83c80! [852719.001645] KVM can't copy data from 0x3fff86683c80! [852719.001655] KVM can't copy data from 0x3fff86683c80! [852719.001658] KVM can't copy data from 0x3fff66a83c80! [852719.001665] KVM can't copy data from 0x3fff86683c80! [852719.001668] KVM can't copy data from 0x3fff66a83c80! [852719.001678] KVM can't copy data from 0x3fff66a83c80! [852719.001686] KVM can't copy data from 0x3fff86683c80! "KVM can't copy data from" error is being logged at very high rate by kernel. rate limiting this error should fix this issue. == Comment: #20 - VIPIN K. PARASHAR <vipar...@in.ibm.com> - 2017-02-23 12:01:26 == Fix for this is submitted to PowerPC mailing list and is available at below location: https://patchwork.ozlabs.org/patch/728831/ It reads: "KVM: PPC: Book3S: Ratelimit copy data failure error messages" To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1667416/+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
