Re: [virtio-comment] [PATCH RESEND v6 1/3] content: Document balloon feature free page hints

[David Hildenbrand <david@redhat.com>]

On 18.08.20 19:32, Alexander Duyck wrote:
> From: Alexander Duyck <alexander.h.duyck@linux.intel.com>
> 
> Free page hints allow the balloon driver to provide information on what
> pages are not currently in use so that we can avoid the cost of copying
> them in migration scenarios. Add a feature description for free page hints
> describing basic functioning and requirements.
> 
> In working on this the specification as pointed out certain issues with the
> Linux driver and QEMU device implementation. The issues include:
> 1. The Linux driver does not re-initialize pages when it reuses them
> before receiving the "DONE" command, as such this can lead to possible data
> corruption.
> 2. The QEMU device is not returning the "DONE" command if a migration
> fails. This results in the guest holding onto pages until forced out by the
> shrinker.
> 
> There are also additional issues that have been found not related to the
> specification.
> 
> There is currently discussion on if the feature should be removed so this
> patch is a place-holder for if we decide to keep the feature and fix the
> issues. Otherwise this patch can be dropped and we can work on a patch to
> document the need to avoid the feature.
> 
> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>

Reviewed-by: David Hildenbrand <david@redhat.com>


-- 
Thanks,

David / dhildenb