Re: [PATCH] xen/balloon: set ballooned out pages as invalid in p2m

[David Vrabel <david.vrabel@citrix.com>]

On 02/07/14 10:40, David Vrabel wrote:
> Since cd9151e26d31048b2b5e00fd02e110e07d2200c9 (xen/balloon: set a
> mapping for ballooned out pages), a ballooned out page had its entry
> in the p2m set to the MFN of one of the scratch pages.  This means
> that the p2m will contain many entries pointing to the same MFN.
> 
> During a domain save, these many-to-one entries are not identified as
> such and the scratch page is saved multiple times. On restore the
> ballooned pages are populated with new frames and the domain may use
> up its allocation before all pages can be restored.
> 
> Since the original fix only needed to keep a mapping for the ballooned
> page it is safe to set ballooned out pages as INVALID_P2M_ENTRY in the
> p2m (as they were before). Thus preventing them from being saved and
> re-populated on restore.

Stefano acked v1 so I've applied to to stable/for-linus-2.16 and tagged
for stable.

David