Re: 2.6.30-rc1 A few issues and a stall

From: Zhang Rui
Date: Sun Apr 12 2009 - 22:05:05 EST


On Sun, 2009-04-12 at 23:24 +0800, Ed Tomlinson wrote:
> Hi,
>
> I got tired of building out of tree DRM drivers so decided to try 2.6.30-rc1. For simple tasks
> it works fine, for slightly more complex ones it is not quite as good...
>
> Here is an example. I normally start a kvm session with the commands below:
>
> ed@grover ~/vm $ sudo modprobe tun
> ed@grover ~/vm $ sudo brctl addbr br0
> ed@grover ~/vm $ sudo ifconfig br0 192.168.100.254 netmask 255.255.255.0 up
> ed@grover ~/vm $ sudo tunctl -b -u ed -t qtap0
> qtap0
> ed@grover ~/vm $ sudo brctl addif br0 qtap0
> ed@grover ~/vm $ sudo ifconfig qtap0 up 0.0.0.0 promisc
> ed@grover ~/vm $ sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
> iptables v1.4.2: can't initialize iptables table `nat': Table does not exist (do you need to insmod?)
> Perhaps iptables or your kernel needs to be upgraded.
>
> Issue 1 - I need to manually modprobe be get iptables to work. This exact procedure worked in 2.6.29.
>
> ed@grover ~/vm $ sudo modprobe nf_nat
> ed@grover ~/vm $ sudo modprobe ipt_MASQUERADE
> ed@grover ~/vm $ sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
>
> Once the above networking stuff is setup I start kvm with the command below
>
> QEMU_AUDIO_DRV=alsa kvm -m 1024 -cdrom /mnt/sdc4/divx/archlinux-2009.02-ftp-i686.iso -boot c -smp 3 -usb -usbdevice tablet -vga std -drive file=arch.img -net nic,macaddr=52:54:00:12:34:23 -net tap,ifname=qtap0,script=no -soundhw all -mem-path /hugepages
>
> which works and the kvm session boots just fine.
>
> Issue 2. When I attempt to ping outside the kvm session the pc (not just the kvm session) hangs.
> Its impossible to kill the kvm session and there are numerious info messages from RCU (tree RCU enabled)
> about stalls.
>
> Issue 3. ACPI is having fun during startup. This does not seem to cause problems later but is
> noisy and probably should be fixed before .30's release.
>
this is a duplicate of bug
http://bugzilla.kernel.org/show_bug.cgi?id=13036
please try the patch in comment #6 there and see if it helps.

thanks,
rui

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