From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: [PATCH] xen/balloon: set ballooned out pages as invalid in p2m Date: Fri, 4 Jul 2014 15:18:13 +0100 Message-ID: <53B6B7A5.70603@citrix.com> References: <1404294054-22691-1-git-send-email-david.vrabel@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1X34Je-0006NI-Ab for xen-devel@lists.xenproject.org; Fri, 04 Jul 2014 14:18:18 +0000 In-Reply-To: <1404294054-22691-1-git-send-email-david.vrabel@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: David Vrabel , xen-devel@lists.xenproject.org Cc: Boris Ostrovsky , Marek Marczykowski , Stefano Stabellini List-Id: xen-devel@lists.xenproject.org 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