netdev - Re: xen-netfront crash when detaching network while some network activity

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Date:	Tue, 1 Dec 2015 23:32:58 +0100
From:	Marek Marczykowski-Górecki 
	<marmarek@...isiblethingslab.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	David Vrabel <david.vrabel@...rix.com>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	Annie Li <annie.li@...cle.com>,
	xen-devel <xen-devel@...ts.xen.org>, netdev@...r.kernel.org
Subject: Re: xen-netfront crash when detaching network while some network
 activity

On Tue, Dec 01, 2015 at 05:00:42PM -0500, Konrad Rzeszutek Wilk wrote:
> On Tue, Nov 17, 2015 at 03:45:15AM +0100, Marek Marczykowski-Górecki wrote:
> > On Wed, Oct 21, 2015 at 08:57:34PM +0200, Marek Marczykowski-Górecki wrote:
> > > On Wed, May 27, 2015 at 12:03:12AM +0200, Marek Marczykowski-Górecki wrote:
> > > > On Tue, May 26, 2015 at 11:56:00AM +0100, David Vrabel wrote:
> > > > > On 22/05/15 12:49, Marek Marczykowski-Górecki wrote:
> > > > > > Hi all,
> > > > > > 
> > > > > > I'm experiencing xen-netfront crash when doing xl network-detach while
> > > > > > some network activity is going on at the same time. It happens only when
> > > > > > domU has more than one vcpu. Not sure if this matters, but the backend
> > > > > > is in another domU (not dom0). I'm using Xen 4.2.2. It happens on kernel
> > > > > > 3.9.4 and 4.1-rc1 as well.
> > > > > > 
> > > > > > Steps to reproduce:
> > > > > > 1. Start the domU with some network interface
> > > > > > 2. Call there 'ping -f some-IP'
> > > > > > 3. Call 'xl network-detach NAME 0'
> 
> Do you see this all the time or just on occassions?

Using above procedure - all the time.

> I tried to reproduce it and couldn't see it. Is your VM an PV or HVM?

PV, started by libvirt. This may have something to do, the problem didn't
existed on older Xen (4.1) and started by xl. I'm not sure about kernel
version there, but I think I've tried there 3.18 too, which has this
problem.

But I don't see anything special in domU config file (neither backend
nor frontend) - it may be some libvirt default. If that's really the
cause. Can I (and how) get any useful information about that?


-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

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