This bug has been quiet for a while by the looks of it so just chipping in. I can confirm I witnessed this bug last week on an Ubuntu 14.04 x64 VM on a Windows Server 2012 R2 Hyper-V server with dynamic memory enabled on the guest. I suspect that dynamic memory (aka. memory hot- add/remove) may be related to this issue. If so, creating a VM with dynamic memory enabled and then running a workload that is memory intensive to ensure the Hyper-V server allocates more RAM to the VM may be beneficial. The tie-in with the balloon driver is interesting, and might suggest there's some level of interaction going on between these two components? Perhaps after dynamic memory adds more RAM to the system the balloon driver may trigger the issue due to no longer valid assumptions, or alternatively, the removal of memory from the system once it no longer needs it has a similar effect?
It may also be useful for others to know that we initially detected this issue due to it causing a very high load average on the affected system which can be trivially detected by monitoring systems like Nagios. Note that while the load average is high, this doesn't correspond to any given process actually consuming substantial CPU resources, so you'll want to take a look at the dmesg output which will confirm if you're experiencing the issue via the blocked systemd-udevd and kworker processes. -- 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/1292400 Title: task systemd-udevd:1906 blocked for more than 120 seconds. Status in “linux” package in Ubuntu: Confirmed Bug description: System log shows repeated incidents of "task systemd-udevd:1906 blocked for more than 120 seconds." ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: linux-image-3.13.0-17-generic 3.13.0-17.37 [modified: boot/vmlinuz-3.13.0-17-generic] ProcVersionSignature: Ubuntu 3.13.0-17.37-generic 3.13.6 Uname: Linux 3.13.0-17-generic x86_64 ApportVersion: 2.13.3-0ubuntu1 Architecture: amd64 AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1: CurrentDesktop: XFCE Date: Fri Mar 14 08:54:36 2014 HibernationDevice: RESUME=UUID=0d223c65-8c7e-41b4-95b3-05b22ff4679b InstallationDate: Installed on 2014-03-12 (1 days ago) InstallationMedia: Xubuntu 14.04 LTS "Trusty Tahr" - Alpha amd64 (20140312) IwConfig: eth0 no wireless extensions. lo no wireless extensions. Lspci: Lsusb: Error: command ['lsusb'] failed with exit code 1: unable to initialize libusb: -99 MachineType: Microsoft Corporation Virtual Machine ProcFB: 0 EFI VGA ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-17-generic.efi.signed root=UUID=61b52c1b-300d-4c30-8966-db1745f4a4bc ro video:hyperv_fb=1920x1080 quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-3.13.0-17-generic N/A linux-backports-modules-3.13.0-17-generic N/A linux-firmware 1.126 RfKill: SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 11/26/2012 dmi.bios.vendor: Microsoft Corporation dmi.bios.version: Hyper-V UEFI Release v1.0 dmi.board.asset.tag: None dmi.board.name: Virtual Machine dmi.board.vendor: Microsoft Corporation dmi.board.version: Hyper-V UEFI Release v1.0 dmi.chassis.asset.tag: 6485-6574-9248-6162-4701-6267-50 dmi.chassis.type: 3 dmi.chassis.vendor: Microsoft Corporation dmi.chassis.version: Hyper-V UEFI Release v1.0 dmi.modalias: dmi:bvnMicrosoftCorporation:bvrHyper-VUEFIReleasev1.0:bd11/26/2012:svnMicrosoftCorporation:pnVirtualMachine:pvrHyper-VUEFIReleasev1.0:rvnMicrosoftCorporation:rnVirtualMachine:rvrHyper-VUEFIReleasev1.0:cvnMicrosoftCorporation:ct3:cvrHyper-VUEFIReleasev1.0: dmi.product.name: Virtual Machine dmi.product.version: Hyper-V UEFI Release v1.0 dmi.sys.vendor: Microsoft Corporation --- ApportVersion: 2.13.3-0ubuntu1 Architecture: amd64 AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1: CurrentDesktop: XFCE DistroRelease: Ubuntu 14.04 HibernationDevice: RESUME=UUID=0d223c65-8c7e-41b4-95b3-05b22ff4679b InstallationDate: Installed on 2014-03-12 (1 days ago) InstallationMedia: Xubuntu 14.04 LTS "Trusty Tahr" - Alpha amd64 (20140312) IwConfig: eth0 no wireless extensions. lo no wireless extensions. Lspci: Lsusb: Error: command ['lsusb'] failed with exit code 1: unable to initialize libusb: -99 MachineType: Microsoft Corporation Virtual Machine Package: linux (not installed) ProcFB: 0 EFI VGA ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-17-generic.efi.signed root=UUID=61b52c1b-300d-4c30-8966-db1745f4a4bc ro video:hyperv_fb=1920x1080 quiet splash vt.handoff=7 ProcVersionSignature: Ubuntu 3.13.0-17.37-generic 3.13.6 RelatedPackageVersions: linux-restricted-modules-3.13.0-17-generic N/A linux-backports-modules-3.13.0-17-generic N/A linux-firmware 1.126 RfKill: Tags: trusty Uname: Linux 3.13.0-17-generic x86_64 UpgradeStatus: No upgrade log present (probably fresh install) UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo _MarkForUpload: True dmi.bios.date: 11/26/2012 dmi.bios.vendor: Microsoft Corporation dmi.bios.version: Hyper-V UEFI Release v1.0 dmi.board.asset.tag: None dmi.board.name: Virtual Machine dmi.board.vendor: Microsoft Corporation dmi.board.version: Hyper-V UEFI Release v1.0 dmi.chassis.asset.tag: 6485-6574-9248-6162-4701-6267-50 dmi.chassis.type: 3 dmi.chassis.vendor: Microsoft Corporation dmi.chassis.version: Hyper-V UEFI Release v1.0 dmi.modalias: dmi:bvnMicrosoftCorporation:bvrHyper-VUEFIReleasev1.0:bd11/26/2012:svnMicrosoftCorporation:pnVirtualMachine:pvrHyper-VUEFIReleasev1.0:rvnMicrosoftCorporation:rnVirtualMachine:rvrHyper-VUEFIReleasev1.0:cvnMicrosoftCorporation:ct3:cvrHyper-VUEFIReleasev1.0: dmi.product.name: Virtual Machine dmi.product.version: Hyper-V UEFI Release v1.0 dmi.sys.vendor: Microsoft Corporation To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1292400/+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
