linux-kernel - Re: [PATCH v2 2/2] KVM: arm64: Add memcg accounting to KVM allocations

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Date:   Tue, 7 Sep 2021 17:29:11 -0500
From:   Oliver Upton <oupton@...gle.com>
To:     Jia He <justin.he@....com>
Cc:     Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>,
        Alexandru Elisei <Alexandru.Elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Xiaoming Ni <nixiaoming@...wei.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Kees Cook <keescook@...omium.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kernel@...r.kernel.org, Liu Shixin <liushixin2@...wei.com>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Will Deacon <will@...nel.org>, kvmarm@...ts.cs.columbia.edu,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 2/2] KVM: arm64: Add memcg accounting to KVM allocations

Hi Jia,

On Tue, Sep 7, 2021 at 7:33 AM Jia He <justin.he@....com> wrote:
>
> Inspired by commit 254272ce6505 ("kvm: x86: Add memcg accounting to KVM
> allocations"), it would be better to make arm64 KVM consistent with
> common kvm codes.
>
> The memory allocations of VM scope should be charged into VM process
> cgroup, hence change GFP_KERNEL to GFP_KERNEL_ACCOUNT.
>
> There remain a few cases since these allocations are global, not in VM
> scope.

I believe there are more memory allocations that could be switched to
GFP_KERNEL_ACCOUNT. For non-pKVM kernels, we probably should charge
all stage-2 paging structure allocations to the VM process. Your patch
appears to only change the allocation of the kvm_pgtable structure,
but not descendent paging structures.

--
Thanks,
Oliver