On 22.10.19 11:14, Michal Hocko wrote:
On Tue 22-10-19 10:32:11, David Hildenbrand wrote:
[...]
E.g., arch/x86/kvm/mmu.c:kvm_is_mmio_pfn()
Thanks for these references. I am not really familiar with kvm so I
cannot really comment on the specific code but I am wondering why
it simply doesn't check for ZONE_DEVICE explicitly? Also we do care
about holes in RAM (from the early boot), those should be reserved
already AFAIR. So we are left with hotplugged memory with holes and
I am not really sure we should bother with this until there is a clear
usecase in sight.
Well, checking for ZONE_DEVICE is only possible if you have an
initialized memmap. And that is not guaranteed when you start mapping
random stuff into your guest via /dev/mem.
I am reworking these patches right now and audit the whole kernel for
PageReserved() checks that might affect ZONE_DEVICE. I'll send the
collection of patches as RFC.
--
Thanks,
David / dhildenb
