Re: [PATCH v1 5/7] mm: introduce page_offline_(begin|end|freeze|unfreeze) to synchronize setting PageOffline()

[David Hildenbrand]

On 02.05.21 08:33, Mike Rapoport wrote:
> On Thu, Apr 29, 2021 at 02:25:17PM +0200, David Hildenbrand wrote:
> > A driver might set a page logically offline -- PageOffline() -- and
> > turn the page inaccessible in the hypervisor; after that, access to page
> > content can be fatal. One example is virtio-mem; while unplugged memory
> > -- marked as PageOffline() can currently be read in the hypervisor, this
> > will no longer be the case in the future; for example, when having
> > a virtio-mem device backed by huge pages in the hypervisor.
> >
> > Some special PFN walkers -- i.e., /proc/kcore -- read content of random
> > pages after checking PageOffline(); however, these PFN walkers can race
> > with drivers that set PageOffline().
> >
> > Let's introduce page_offline_(begin|end|freeze|unfreeze) for
>
> Bikeshed: freeze|thaw?

Sure :)


--
Thanks,

David / dhildenb