Re: [Xen-devel] [PATCH] Fix balloon handling of highmem pages

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> Applied, but have you tested with 'mem=' on the domain cmdline to give it a
> memmap bigger than its original allocation of memory? In this case it looks
> like the code in mm/init-xen.c does the right thing in tandem with this
> patch (i.e., it increments totalhigh_pages for each not-currently-present
> page, and you then decrement again when the not-present pages get added to
> the balloon). But I'm not 100% certain and it could do with being tested.

Good point.

I checked through that code, and agreed with your assessment.  Also just 
tested it, my domain booted successfully with mem=4G and was able to expand 
(and shrink again) without exploding or doing anything obviously crazy.

Cheers,
Mark

>  Thanks,
>  Keir
>
> On 29/6/07 16:53, "Mark Williamson" <mark.williamson@xxxxxxxxxxxx> wrote:
> > I knocked up a quick patch to fix the balloon driver's handling of
> > highmem pages.  Should apply cleanly to the Linux dev tree.  I can also
> > submit it for 3.1 if wanted.
> >
> > Without this, LowTotal can go negative (given it's an unsigned integer)
> > and then appears as ~4Gig, which is a bit silly.
> >
> > I beliee this fixes Anthony Wright's bug #733 in Bugzilla
> > (http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=733).  Credit to
> > Anthony for noticing the problem, and figuring out that he was actually
> > seeing an unsigned int going "negative".
> >
> > Cheers,
> > Mark



-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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