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[209.85.220.65]) by mx.google.com with SMTPS id v17sor7133048wrw.44.2019.07.05.08.52.41 for (Google Transport Security); Fri, 05 Jul 2019 08:52:41 -0700 (PDT) Received-SPF: pass (google.com: domain of chris@chrisdown.name designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@chrisdown.name header.s=google header.b=pmbWR2rZ; spf=pass (google.com: domain of chris@chrisdown.name designates 209.85.220.65 as permitted sender) smtp.mailfrom=chris@chrisdown.name; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=chrisdown.name DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chrisdown.name; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=yxeDn3omZDASV5TPIJX6WDwy+V0DYxxm+ivyAUGtHnM=; b=pmbWR2rZ96zCWqBywO5tBsLFDu0cTvqu4TdanVzpSWUVN/gYu5AkG4t/O/SZuUiFd7 fkYXo+el81P61XMz45+6FgQu+1qcw2Inl9NNrMoA3dUVciG5+8ns0eclhq7P4JStfHT+ pwGKg11mhR0gU+h198Fc2mH8s1UEVKDxntr3I= X-Google-Smtp-Source: APXvYqzqnCAUiDwHCeuXJUahY/4HU2LXpyk6UjQ2Ay4NSextLvLHR2uu7rfvGqlCREpoURzSBepaTQ== X-Received: by 2002:a5d:43d0:: with SMTP id v16mr4457975wrr.252.1562341960595; Fri, 05 Jul 2019 08:52:40 -0700 (PDT) Received: from localhost ([2620:10d:c092:180::1:7d8d]) by smtp.gmail.com with ESMTPSA id h6sm9962003wre.82.2019.07.05.08.52.39 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 05 Jul 2019 08:52:40 -0700 (PDT) Date: Fri, 5 Jul 2019 16:52:39 +0100 From: Chris Down To: Yafang Shao Cc: Michal Hocko , Andrew Morton , Linux MM , Johannes Weiner , Vladimir Davydov , Shakeel Butt , Yafang Shao Subject: Re: [PATCH] mm, memcg: support memory.{min, low} protection in cgroup v1 Message-ID: <20190705155239.GA18699@chrisdown.name> References: <1562310330-16074-1-git-send-email-laoar.shao@gmail.com> <20190705090902.GF8231@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.1 (2019-06-15) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Yafang Shao writes: >> Cgroup v1 API is considered frozen with new features added only to v2. > >The facilities support both cgroup v1 and cgroup v2, and what we need >to do is only exposing the interface. >If the cgroup v1 API is frozen, it will be a pity. This might be true in the absolute purest technical sense, but not in a practical one. Just exposing the memory protection interface without making it comprehend v1's API semantics seems a bad move to me -- for example, how it (and things like effective protections) interact without the no internal process constraint, and certainly many many more things that nobody has realised are not going to work yet. And to that extent, you're really implicitly asking for a lot of work and evaluation to be done on memory protections for an interface which is already frozen. I'm quite strongly against that. >Because the interfaces between cgroup v1 and cgroup v2 are changed too >much, which is unacceptable by our customer. The problem is that you're explicitly requesting to use functionality which under the hood relies on that new interface while also requesting to not use that new interface at the same time :-) While it may superficially work without it, I'm sceptical that simply adding memory.low and memory.min to the v1 hierarchy is going to end up with reasonable results under scrutiny, or a coherent system or API.