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Subject: Re: [PATCH RESEND 8/8] af_unix: charge buffers to kmemcg
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, "David S. Miller"
	 <davem@davemloft.net>, Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko
	 <mhocko@kernel.org>, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
	netdev@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org
Date: Tue, 24 May 2016 06:02:06 -0700
In-Reply-To: <fcfe6cae27a59fbc5e40145664b3cf085a560c68.1464079538.git.vdavydov@virtuozzo.com>
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	 <fcfe6cae27a59fbc5e40145664b3cf085a560c68.1464079538.git.vdavydov@virtuozzo.com>
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On Tue, 2016-05-24 at 11:49 +0300, Vladimir Davydov wrote:
> Unix sockets can consume a significant amount of system memory, hence
> they should be accounted to kmemcg.
> 
> Since unix socket buffers are always allocated from process context,
> all we need to do to charge them to kmemcg is set __GFP_ACCOUNT in
> sock->sk_allocation mask.

I have two questions : 

1) What happens when a buffer, allocated from socket <A> lands in a
different socket <B>, maybe owned by another user/process.

Who owns it now, in term of kmemcg accounting ?

2) Has performance impact been evaluated ?

Thanks.



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