[libvirt] [BUG] mlock support breakage

[Daniel P. Berrange]

On Mon, Mar 13, 2017 at 02:08:30PM -0400, Luiz Capitulino wrote:
> On Mon, 13 Mar 2017 13:53:33 -0400
> Luiz Capitulino <lcapitulino at redhat.com> wrote:
> 
> > OK, you're right. I personally don't like we're putting a random cap
> > on QEMU memory allocations, but if it's large enough it shouldn't be
> > a problem (I hope).
> 
> The I hope part meaning, if we do find legitimate reasons for QEMU's
> address space to go beyond $LARGE_NUMBER, it will be means of guests
> randomly crashing when using <locked/>.

NB if we did enforce $RAM + $LARGE_NUMBER, then I'd suggest we did
set a default hard_limit universally once more, not only set a mlock
limit when using <locked/>. This would at least ensure we see consistent
(bad) behaviour rather than have edge cases that only appeared when
<locked/> was present.

We would need $LARGE_NUMBER to be much more conservative than what we
used in the past though, to avoid hitting the same problems once again.

Regards,
Daniel
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