SRU: [PATCH] KVM: add schedule check to napi_enable call

[Ken Stailey]

--- On Mon, 2/7/11, Stefan Bader <stefan.bader at canonical.com> wrote:

> From: Stefan Bader <stefan.bader at canonical.com>
> Subject: Re: SRU: [PATCH] KVM: add schedule check to napi_enable call
> To: kernel-team at lists.ubuntu.com
> Date: Monday, February 7, 2011, 7:50 AM
> On 02/05/2011 09:20 PM, Ken Stailey
> wrote:
> > SRU Justification:
> > 
> > Impact: Under heavy network I/O load virtio-net driver
> crashes making VM guest unusable.
> > 
> > Testcase: I left a current Lucid VM running two
> concurrent "scp -r" of > 200 GB from NFS read-only source
> to a physical remote host overnight.  VM quickly
> started emitting "page allocation errors" in the system
> log.  Next morning when I checked the VM I could still
> ping it but could not establish an SSH connection.
> > 
> > Fix: This patch from Bruce Rogers at Novell
> > 
> > * [PATCH] KVM: add schedule check to napi_enable
> call
> >     - http://kerneltrap.org/mailarchive/linux-netdev/2010/6/4/6278660
> > 
> > BugLink: https://bugs.launchpad.net/bugs/579276
> > 
> > 
> > 
> The patch itself looks reasonable. But this has not made
> its way upstream. The mail thread seems to be reasonably old, so the
> question would be why it is still missing.

I have reason to believe that the absence of this patch in upstream kernels is a critical oversight.

I used "apt-add-repository ppa:kernel-ppa/ppa" to put the "Natty" kernel on my Lucid test VM

$ uname -a
Linux dubnium 2.6.38-2-server #29~lucid1-Ubuntu SMP Mon Feb 7 15:09:10 UTC 2011 x86_64 GNU/Linux

The stress test crashed the VM's network driver after copying only 63 GB.  

The test consists of running "scp -r /nfs_read_only/1 remote:/dir/1" concurrently with "scp -r /nfs_read_only/2 remote:/dir/2"

The NFS mount options on the client are:
ro,tcp,hard,intr,sloppy,addr=10.1.1.1

> We need patches upstream before they can be SRUed.
> Have you tried contacting Bruce or Olaf to ask what happened there?
> 
> -Stefan

Who is Olaf?

Thanks,
Ken