I get about 9 of these near the start of the system while userspace is
first coming up.  The  virtual machine in question is mostly Fedora 14
with a kernel from linux-next as of today.  The hardware is RHEL 5.5
with KVM:

tree: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
tag: next-20100412
commit: bbeecf185fe464ccd7ee97ce6d3646ad686995b4

I'm not sure what else to collect, give, test, try, show, debug or what
have you so let me know.  Attached is my full dmesg and config.

[   14.203970] BUG: using smp_processor_id() in preemptible [00000000] code: avahi-daemon/2093
[   14.204025] caller is netif_rx+0xfa/0x110
[   14.204032] Pid: 2093, comm: avahi-daemon Tainted: G        W  2.6.34-rc3-next-20100412+ #65
[   14.204035] Call Trace:
[   14.204064]  [<ffffffff81278fe5>] debug_smp_processor_id+0x105/0x110
[   14.204070]  [<ffffffff8142163a>] netif_rx+0xfa/0x110
[   14.204090]  [<ffffffff8145b631>] ip_dev_loopback_xmit+0x71/0xa0
[   14.204095]  [<ffffffff8145b892>] ip_mc_output+0x192/0x2c0
[   14.204099]  [<ffffffff8145d610>] ip_local_out+0x20/0x30
[   14.204105]  [<ffffffff8145d8ad>] ip_push_pending_frames+0x28d/0x3d0
[   14.204119]  [<ffffffff8147f1cc>] udp_push_pending_frames+0x14c/0x400
[   14.204125]  [<ffffffff814803fc>] udp_sendmsg+0x39c/0x790
[   14.204137]  [<ffffffff814891d5>] inet_sendmsg+0x45/0x80
[   14.204149]  [<ffffffff8140af91>] sock_sendmsg+0xf1/0x110
[   14.204177]  [<ffffffff810e3a89>] ? might_fault+0xb9/0xd0
[   14.204184]  [<ffffffff810e3a3e>] ? might_fault+0x6e/0xd0
[   14.204189]  [<ffffffff8140dc6c>] sys_sendmsg+0x20c/0x380
[   14.204205]  [<ffffffff811107f1>] ? do_sync_write+0xd1/0x110
[   14.204211]  [<ffffffff810e3a3e>] ? might_fault+0x6e/0xd0
[   14.204233]  [<ffffffff8100ad82>] system_call_fastpath+0x16/0x1b