Re: Trying to make use of hotplug memory for xen balloon driver

From: Dave Hansen
Date: Fri Mar 28 2008 - 14:21:33 EST


On Thu, 2008-03-27 at 15:23 -0700, Jeremy Fitzhardinge wrote:
> If the user does a mass online via /sys the system explodes because it
> onlines a large number of pages which have no backing memory. Since
> none of those pages can be mapped, the kernel explodes in a variety of
> interesting ways.

Yeah, it does look like you need some kind of partial onlining.

> So I'd really like to inhibit the sysfs interface on these sections.
> Thoughts?

The balloon driver isn't an exact fit for memory hotplug as it stands,
so there are going to be a few growing pains here. :)

I'm not sure just inhibiting sysfs is the best thing. What would you
think about adding partial sections, initializing the 'struct page's,
but just not touching the memory?

-- Dave

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