Re: [PATCH 3/5] vhost: support upto 509 memory regions

From: Michael S. Tsirkin
Date: Wed Jun 17 2015 - 07:52:10 EST

On Wed, Jun 17, 2015 at 01:48:03PM +0200, Igor Mammedov wrote:
> > > So far it's kernel limitation and this patch fixes crashes
> > > that users see now, with the rest of patches enabling performance
> > > not to regress.
> >
> > When I say regression I refer to an option to limit the array
> > size again after userspace started using the larger size.
> Is there a need to do so?

Considering userspace can be malicious, I guess yes.

> Userspace that cares about memory footprint won't use many slots
> keeping it low and user space that can't do without many slots
> or doesn't care will have bigger memory footprint.

We really can't trust userspace to do the right thing though.

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