linux-kernel - Re: [PATCH] kvm, mm: account kvm related kmem slabs to kmemcg

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Message-ID: <9f9dce19-3ee2-ace7-e54a-9c8f9b89080c@redhat.com>
Date:   Fri, 6 Oct 2017 10:55:00 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Shakeel Butt <shakeelb@...gle.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Michal Hocko <mhocko@...nel.org>,
        Greg Thelen <gthelen@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Christian Borntraeger <borntraeger@...ibm.com>,
        James Hogan <james.hogan@...tec.com>,
        Christoffer Dall <christoffer.dall@...aro.org>,
        Paul Mackerras <paulus@...abs.org>,
        David Gibson <dgibson@...hat.com>
Subject: Re: [PATCH] kvm, mm: account kvm related kmem slabs to kmemcg

On 06/10/2017 03:07, Shakeel Butt wrote:
> The kvm slabs can consume a significant amount of system memory
> and indeed in our production environment we have observed that
> a lot of machines are spending significant amount of memory that
> can not be left as system memory overhead. Also the allocations
> from these slabs can be triggered directly by user space applications
> which has access to kvm and thus a buggy application can leak
> such memory. So, these caches should be accounted to kmemcg.
> 
> Signed-off-by: Shakeel Butt <shakeelb@...gle.com>
> ---
>  arch/x86/kvm/mmu.c  | 4 ++--
>  virt/kvm/kvm_main.c | 2 +-
>  2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index eca30c1eb1d9..87c5db9e644d 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -5475,13 +5475,13 @@ int kvm_mmu_module_init(void)
>  
>  	pte_list_desc_cache = kmem_cache_create("pte_list_desc",
>  					    sizeof(struct pte_list_desc),
> -					    0, 0, NULL);
> +					    0, SLAB_ACCOUNT, NULL);
>  	if (!pte_list_desc_cache)
>  		goto nomem;
>  
>  	mmu_page_header_cache = kmem_cache_create("kvm_mmu_page_header",
>  						  sizeof(struct kvm_mmu_page),
> -						  0, 0, NULL);
> +						  0, SLAB_ACCOUNT, NULL);
>  	if (!mmu_page_header_cache)
>  		goto nomem;
>  
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 9deb5a245b83..3d73299e05f2 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -4010,7 +4010,7 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
>  	if (!vcpu_align)
>  		vcpu_align = __alignof__(struct kvm_vcpu);
>  	kvm_vcpu_cache = kmem_cache_create("kvm_vcpu", vcpu_size, vcpu_align,
> -					   0, NULL);
> +					   SLAB_ACCOUNT, NULL);
>  	if (!kvm_vcpu_cache) {
>  		r = -ENOMEM;
>  		goto out_free_3;
> 

Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>

Adding maintainers for other architectures, because they probably want
to do something similar.

Paolo