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

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Date:   Thu, 02 Sep 2021 19:11:48 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Jia He <justin.he@....com>
Cc:     James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Liu Shixin <liushixin2@...wei.com>,
        Eric Auger <eric.auger@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Shenming Lu <lushenming@...wei.com>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Xiaoming Ni <nixiaoming@...wei.com>,
        Zenghui Yu <yuzenghui@...wei.com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] KVM: arm64: Add memcg accounting to KVM allocations

On Thu, 02 Sep 2021 01:28:01 +0100,
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 remained a few cases since these allocations are global, not in VM
> scope.
> 
> Signed-off-by: Jia He <justin.he@....com>
> ---
>  arch/arm64/kvm/arm.c      | 6 ++++--
>  arch/arm64/kvm/mmu.c      | 2 +-
>  arch/arm64/kvm/pmu-emul.c | 2 +-
>  arch/arm64/kvm/reset.c    | 2 +-
>  4 files changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index e9a2b8f27792..9d6f5bcaddef 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -289,10 +289,12 @@ long kvm_arch_dev_ioctl(struct file *filp,
>  
>  struct kvm *kvm_arch_alloc_vm(void)
>  {
> +	unsigned long sz = sizeof(struct kvm);

If you are going to introduce an extra variable, please use the
correct type (size_t).

> +
>  	if (!has_vhe())
> -		return kzalloc(sizeof(struct kvm), GFP_KERNEL);
> +		return kzalloc(sz, GFP_KERNEL | GFP_KERNEL_ACCOUNT);

Why both GFP_KERNEL and GFP_KERNEL_ACCOUNT?

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.