linux-kernel - Re: [PATCH v2] kvm, mm: account shadow page tables to kmemcg

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Date:   Fri, 29 Jun 2018 17:43:06 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Shakeel Butt <shakeelb@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-mm@...ck.org, Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Greg Thelen <gthelen@...gle.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Peter Feiner <pfeiner@...gle.com>, stable@...r.kernel.org
Subject: Re: [PATCH v2] kvm, mm: account shadow page tables to kmemcg

On 29/06/2018 16:55, Michal Hocko wrote:
>>> I would also love to see a note how this memory is bound to the owner
>>> life time in the changelog. That would make the review much more easier.
>> --verbose for people that aren't well versed in linux mm, please...
> Well, if the memory accounted to the memcg hits the hard limit and there
> is no way to reclaim anything to reduce the charged memory then we have
> to kill something. Hopefully the memory hog. If that one dies it would
> be great it releases its charges along the way. My remark was just to
> explain how that would happen for this specific type of memory. Bound to
> a file, has its own tear down etc. Basically make life of reviewers
> easier to understand the lifetime of charged objects without digging
> deep into the specific subsystem.

Oh I see.  Yes, it's all freed when the VM file descriptor (which you
get with a ioctl on /dev/kvm) is closed.

Thanks,

Paolo