Re: [PATCH] KVM: arm: memcg awareness

[Paolo Bonzini]

On 17/03/21 10:10, Marc Zyngier wrote:
> > @@ -366,7 +366,7 @@ static int hyp_map_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
> >   	if (WARN_ON(level == KVM_PGTABLE_MAX_LEVELS - 1))
> >   		return -EINVAL;
> >   
> > -	childp = (kvm_pte_t *)get_zeroed_page(GFP_KERNEL);
> > +	childp = (kvm_pte_t *)get_zeroed_page(GFP_KERNEL_ACCOUNT);
> No, this is wrong.
>
> You cannot account the hypervisor page tables to the guest because we
> don't ever unmap them, and that we can't distinguish two data
> structures from two different VMs occupying the same page.

If you never unmap them, there should at least be a shrinker to get rid 
of unused pages in the event of memory pressure.

Paolo