Messages in this thread | | | Subject | Re: [PATCH] KVM: arm: memcg awareness | From | Paolo Bonzini <> | Date | Wed, 17 Mar 2021 11:55:00 +0100 |
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On 17/03/21 11:53, Marc Zyngier wrote: > On Wed, 17 Mar 2021 10:40:23 +0000, > Paolo Bonzini <pbonzini@redhat.com> wrote: >> >> 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. > > We don't track where these pages are coming from or whether they can > safely be unmapped. Until we can track such ownership and deal with > page sharing, these mappings have to stay, > > At most, this represent the amount of memory required to map the whole > of the linear mapping.
Ah, these are the EL2 pages, not the stage2 page tables, right? If so, sorry for the noise.
Paolo
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