Red Hat Bugzilla – Bug 212826
xen_net: Memory squeeze in netback driver.
Last modified: 2009-12-14 15:38:40 EST
Description of problem:
Networking between all domains fails. The following message is flodding all
domains ( dmo0 + domU ) /var/log/messages : "xen_net: Memory squeeze in netback
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. make network traffic between domU and dom0. For example:
root@xendom0# ping xendomU1
/var/log/messages get's flooded on dom0 and on all domU ( even those not on the
same virtual-network (bridge) )
Should work :-)
When do these occur? On boot? On domain creation? Under load? What
networking configuration are you using?
They occure when the first few bytes are going over any bridge.
It doesn't matter from which system the data is comming from or going to as long
at least one of them is on xenbr(0-2), which actually means any domain in my
The System has 2 phys. networkinterfaces. Each of them is connected to a bridge.
One bridge for the LAN, another for the internet connection. There is also a
pure virtual bridge for the DMZ.
dom0 domU*(multiple internal systems)
xenbr1 (DMZ) - domU*(multiple DMZ systems)
domU running kernel-xenU-2.6.17-1.2174_FC5 breaks networking with dom0
When all domUs are running 2.6.17-1.2187_FC5xenU everything works fine. Booting
one with kernel-xenU-2.6.17-1.2174_FC5 breaks everything on all xenbr*. After
stopping the "bad" domU everything resumed working.
So when you have one 2174 kernel running, all other domains fail all the time?
That one domain breaks all the others? Or is only the 2174 domain itself broken?
Yes. All interfaces connected to a xenbridge become unavailable. Even those
which are not on the same xenbridge. The only devices that are still working are
the physical devices on dom0.
I've removed all domains from autostart and started each domU manually.
First i've started my firewall/router domU which seperates the LAN from the DMZ
and pinged it from dom0 and it worked. Then started the outer firewall/router
domU and it was pingable too. After starting a domU connected to (xenbr0) with
the 2174 kernel the pings to my outer router stopped. After shutting it down the
pings made theire way again. Since it was the only domU still on 2174 i've
upgraded it and tried again and everything worked. Since i have the old kernel
still installed it's very easy form me to reproduce. If you want any traces
please let me know.
What do you see if you run a tcpdump on the interface of the 2174 domU (both in
the domU and in dom0)?
change QA contact
This report targets FC6, which is now end-of-life.
Please re-test against Fedora 7 or later, and if the issue persists, open a new bug.