Re: [Xen-devel] free_domheap_pages() leaking xenheap pages?

[Keir Fraser <keir@xxxxxxxxxxxxx>]

On 23/1/07 16:25, "Daniel Stodden" <stodden@xxxxxxxxxx> wrote:

> the page range remains unlisted upon return, and if there's any later
> point in the domain life cycle where these pages would ever return to
> the xen heap, i'm unable to find it.

There are very few xenheap pages that are ever shared with guests. These are
shared_info and grant-table pages. We don't want the pages to be completely
freed until the hypervisor is done with them which is not until
domain_destruct(). But Xen itself cannot keep an explicit reference on the
pages since that would stop the domain reference count ever falling to zero,
which would prevent domain_destruct() from ever being called! So Xen does
not increment the reference count and instead takes responsibility for
'manually' freeing the pages in domain_destruct() (at which point we know
that there are no other references to those pages).

 -- Keir


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