[Bug 453617] [NEW] kvm hangs at 100% cpu when connecting to forwarded ports

Jesse Michael jesse.michael at comcast.net
Sat Oct 17 01:28:10 BST 2009

Public bug reported:

Binary package hint: qemu-kvm

If kvm is started using two separate "-net user,hostfwd=<forwarding
rule>" arguments to forward ports from the host to the client, it won't
complain, but will return a connection refused error and hang at 100%
cpu when trying to connect to either forwarded port.

However, if kvm is started with the hostfwd rules combined together into
a single "-net user" argument, it works fine.

As an example, this command line doesn't generate any warnings or
errors, but causes kvm to hang for me:

kvm -net nic -net user,hostfwd=tcp: -net
user,hostfwd=tcp: -m 128 -smp 1 -drive

... but this command line works fine:

kvm -net nic -net
user,hostfwd=tcp:,hostfwd=tcp: -m
128 -smp 1 -drive file=disk0.qcow2

ProblemType: Bug
Architecture: amd64
Date: Fri Oct 16 17:19:59 2009
DistroRelease: Ubuntu 9.10
KvmCmdLine: Error: command ['ps', '-C', 'kvm', '-F'] failed with exit code 1: UID        PID  PPID  C    SZ   RSS PSR STIME TTY          TIME CMD
MachineType: Sony Corporation VGN-SZ650N
NonfreeKernelModules: nvidia
Package: kvm (not installed)
 Socket 0:
   no product info available
 Socket 0:
   no card
ProcCmdLine: root=UUID=3ee4953e-48f0-497c-ae78-18cbb18cfef8 ro quiet splash
 PATH=(custom, user)
ProcVersionSignature: Ubuntu 2.6.31-14.47-generic
SourcePackage: qemu-kvm
Uname: Linux 2.6.31-14-generic x86_64
dmi.bios.date: 07/12/2007
dmi.bios.vendor: Phoenix Technologies LTD
dmi.bios.version: R0081S5
dmi.board.asset.tag: N/A
dmi.board.name: VAIO
dmi.board.vendor: Sony Corporation
dmi.board.version: N/A
dmi.chassis.type: 10
dmi.chassis.vendor: Sony Corporation
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvrR0081S5:bd07/12/2007:svnSonyCorporation:pnVGN-SZ650N:pvrJ002VXGP:rvnSonyCorporation:rnVAIO:rvrN/A:cvnSonyCorporation:ct10:cvrN/A:
dmi.product.name: VGN-SZ650N
dmi.product.version: J002VXGP
dmi.sys.vendor: Sony Corporation

** Affects: qemu-kvm (Ubuntu)
     Importance: Undecided
         Status: New

** Tags: amd64 apport-bug

kvm hangs at 100% cpu when connecting to forwarded ports
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