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

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Message-Id: <a6707959-fe38-0bf6-5281-1c60ba63bc8c@linux.vnet.ibm.com>
Date:   Fri, 6 Oct 2017 09:58:30 +0530
From:   Anshuman Khandual <khandual@...ux.vnet.ibm.com>
To:     Shakeel Butt <shakeelb@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.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
Subject: Re: [PATCH] kvm, mm: account kvm related kmem slabs to kmemcg

On 10/06/2017 06:37 AM, 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.

But there may be other situations like this where user space can
trigger allocation from various SLAB objects inside the kernel
which are accounted as system memory. So how we draw the line
which ones should be accounted for memcg. Just being curious.