Messages in this thread | | | Date | Tue, 25 May 2021 10:20:36 +0200 | From | Oscar Salvador <> | Subject | Re: [PATCH v2 5/6] virtio-mem: use page_offline_(start|end) when setting PageOffline() |
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On Fri, May 14, 2021 at 07:22:46PM +0200, David Hildenbrand wrote: > Let's properly use page_offline_(start|end) to synchronize setting > PageOffline(), so we won't have valid page access to unplugged memory > regions from /proc/kcore. > > Existing balloon implementations usually allow reading inflated memory; > doing so might result in unnecessary overhead in the hypervisor, which > is currently the case with virtio-mem. > > For future virtio-mem use cases, it will be different when using shmem, > huge pages, !anonymous private mappings, ... as backing storage for a VM. > virtio-mem unplugged memory must no longer be accessed and access might > result in undefined behavior. There will be a virtio spec extension to > document this change, including a new feature flag indicating the > changed behavior. We really don't want to race against PFN walkers > reading random page content. > > Acked-by: Michael S. Tsirkin <mst@redhat.com> > Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
-- Oscar Salvador SUSE L3
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