On 11.04.24 23:28, Andrew Morton wrote:
On Thu, 11 Apr 2024 18:14:39 +0200 David Hildenbrand <david@xxxxxxxxxx> wrote:
This series fixes one issue with uffd + shared zeropages on s390x and
fixes that "ordinary" KVM guests can make use of shared zeropages again.
...
Without the shared zeropage, during (2), the VM would suddenly consume
100 GiB on the migration source and destination. On the migration source,
where we don't excpect memory overcommit, we could easilt end up crashing
the VM during migration.
Independent of that, memory handed back to the hypervisor using "free page
reporting" would end up consuming actual memory after the migration on the
destination, not getting freed up until reused+freed again.
Is a backport desirable?
If so, the [1/2] Fixes dates back to 2015 and the [2/2] Fixes is from
2017. Is it appropriate that the patches be backported so far back,
and into different kernel versions?
[2/2] won't be easy to backport to kernels without FAULT_FLAG_UNSHARE,
so I wouldn't really suggest backports to kernels before that. [1/2]
might be reasonable to backport, but might require some tweaking (page
vs. folio).
--
Cheers,
David / dhildenb
