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

[Ken Stailey]

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