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[195.135.220.15]) by mx.google.com with ESMTPS id c10si2727633ede.439.2019.04.16.07.40.00 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 16 Apr 2019 07:40:01 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 366E2AE56; Tue, 16 Apr 2019 14:40:00 +0000 (UTC) Date: Tue, 16 Apr 2019 16:39:58 +0200 From: Michal Hocko To: Dave Hansen Cc: Yang Shi , mgorman@techsingularity.net, riel@surriel.com, hannes@cmpxchg.org, akpm@linux-foundation.org, keith.busch@intel.com, dan.j.williams@intel.com, fengguang.wu@intel.com, fan.du@intel.com, ying.huang@intel.com, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [v2 RFC PATCH 0/9] Another Approach to Use PMEM as NUMA Node Message-ID: <20190416143958.GI11561@dhcp22.suse.cz> References: <1554955019-29472-1-git-send-email-yang.shi@linux.alibaba.com> <20190412084702.GD13373@dhcp22.suse.cz> <20190416074714.GD11561@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) 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: On Tue 16-04-19 07:30:20, Dave Hansen wrote: > On 4/16/19 12:47 AM, Michal Hocko wrote: > > You definitely have to follow policy. You cannot demote to a node which > > is outside of the cpuset/mempolicy because you are breaking contract > > expected by the userspace. That implies doing a rmap walk. > > What *is* the contract with userspace, anyway? :) > > Obviously, the preferred policy doesn't have any strict contract. > > The strict binding has a bit more of a contract, but it doesn't prevent > swapping. Yes, but swapping is not a problem for using binding for memory partitioning. > Strict binding also doesn't keep another app from moving the > memory. I would consider that a bug. -- Michal Hocko SUSE Labs