Re: [PATCHv7 3/3] vhost_net: a kernel-level virtio server
From: Andi Kleen
Date: Wed Nov 04 2009 - 08:37:35 EST
On Wed, Nov 04, 2009 at 03:17:36PM +0200, Michael S. Tsirkin wrote:
> On Wed, Nov 04, 2009 at 02:15:33PM +0100, Andi Kleen wrote:
> > On Wed, Nov 04, 2009 at 03:08:28PM +0200, Michael S. Tsirkin wrote:
> > > On Wed, Nov 04, 2009 at 01:59:57PM +0100, Andi Kleen wrote:
> > > > > Fine?
> > > >
> > > > I cannot say -- are there paths that could drop the device beforehand?
> > >
> > > Do you mean drop the mm reference?
> > No the reference to the device, which owns the mm for you.
> The device is created when file is open and destroyed
> when file is closed. So I think the fs code handles the
> reference counting for me: it won't call file cleanup
> callback while some userspace process has the file open.
But the semantics when someone inherits such a fd through exec
or through file descriptor passing would be surely "interesting"
You would still do IO on the old VM.
I guess it would be a good way to confuse memory accounting schemes
or administrators @)
It would be all saner if this was all a single atomic step.
ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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