This problem has caused more serious damage recently. When nbd dies and printk()s like mad, the serial console is not fast enough to display it.
The kernel keeps allocating buffer space for serial output, which we see as 13G kmalloc-256 or kmalloc-512 kernel threads. Eventually the OOMkiller tries to free up space, but it can only kill userspace programs so ultimately the system dies altogether. This is more dire than mere CPU load or lockup warning messages. -- 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/1505564 Title: Soft lockup with "block nbdX: Attempted send on closed socket" spam Status in linux package in Ubuntu: In Progress Bug description: Some of our nova compute hosts regularly freeze, sometimes for a few hours, with kern.log getting spammed with: block nbdX: Attempted send on closed socket and a few "CPU soft lockup" messages (see attached log). This clears up when the queue gets cleared, eg : block nbdX: queue cleared trusty hosts with kernel version 3.19.0-30-generic. --- AlsaDevices: total 0 crw-rw---- 1 root audio 116, 1 Nov 24 12:23 seq crw-rw---- 1 root audio 116, 33 Nov 24 12:23 timer AplayDevices: Error: [Errno 2] No such file or directory ApportVersion: 2.14.1-0ubuntu3.19 Architecture: amd64 ArecordDevices: Error: [Errno 2] No such file or directory AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1: DistroRelease: Ubuntu 14.04 IwConfig: Error: [Errno 2] No such file or directory MachineType: HP ProLiant DL385 G7 Package: linux (not installed) PciMultimedia: ProcEnviron: TERM=screen-256color PATH=(custom, no user) LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 radeondrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.19.0-36-generic root=UUID=13289ac9-8dc9-4feb-b6bd-ca7db66b21d6 ro console=tty0 console=ttyS1,38400 nosplash crashkernel=384M-:512M nox2apic intremap=off ProcVersionSignature: Ubuntu 3.19.0-36.41~14.04.1hf00090138v20151122b1-generic 3.19.8-ckt9 RelatedPackageVersions: linux-restricted-modules-3.19.0-36-generic N/A linux-backports-modules-3.19.0-36-generic N/A linux-firmware 1.127.18 RfKill: Error: [Errno 2] No such file or directory Tags: trusty uec-images Uname: Linux 3.19.0-36-generic x86_64 UpgradeStatus: No upgrade log present (probably fresh install) UserGroups: _MarkForUpload: True dmi.bios.date: 02/02/2014 dmi.bios.vendor: HP dmi.bios.version: A18 dmi.chassis.type: 23 dmi.chassis.vendor: HP dmi.modalias: dmi:bvnHP:bvrA18:bd02/02/2014:svnHP:pnProLiantDL385G7:pvr:cvnHP:ct23:cvr: dmi.product.name: ProLiant DL385 G7 dmi.sys.vendor: HP To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1505564/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : email@example.com Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp