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Subject: Re: [Qemu-devel] [PATCH kernel 1/2] mm: add the related functions
 to build the free page bitmap
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To: "Li, Liang Z" <liang.z.li@intel.com>, "mst@redhat.com" <mst@redhat.com>, "viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "quintela@redhat.com" <quintela@redhat.com>, "amit.shah@redhat.com" <amit.shah@redhat.com>, "pbonzini@redhat.com" <pbonzini@redhat.com>, "dgilbert@redhat.com" <dgilbert@redhat.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>, "kvm@vger.kernel.org" <kvm@vger.kernel.org>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, "agraf@suse.de" <agraf@suse.de>, "borntraeger@de.ibm.com" <borntraeger@de.ibm.com>

On Tue, 2016-04-19 at 15:02 +0000, Li, Liang Z wrote:
> > 
> > On Tue, 2016-04-19 at 22:34 +0800, Liang Li wrote:
> > > 
> > > The free page bitmap will be sent to QEMU through virtio
> > > interface and
> > > used for live migration optimization.
> > > Drop the cache before building the free page bitmap can get more
> > > free
> > > pages. Whether dropping the cache is decided by user.
> > > 
> > How do you prevent the guest from using those recently-freed pages
> > for
> > something else, between when you build the bitmap and the live
> > migration
> > completes?
> Because the dirty page logging is enabled before building the bitmap,
> there is no need
> to prevent the guest from using the recently-freed pages ...

Fair enough.

It would be good to have that mentioned in the
changelog.