From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f69.google.com (mail-wm0-f69.google.com [74.125.82.69]) by kanga.kvack.org (Postfix) with ESMTP id 0305A6B0033 for ; Wed, 1 Feb 2017 03:53:29 -0500 (EST) Received: by mail-wm0-f69.google.com with SMTP id q124so3870805wmg.2 for ; Wed, 01 Feb 2017 00:53:28 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id u73si24000934wrc.271.2017.02.01.00.53.27 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 01 Feb 2017 00:53:27 -0800 (PST) Date: Wed, 1 Feb 2017 09:53:26 +0100 From: Michal Hocko Subject: Re: [RFC] cpuset: Enable changing of top_cpuset's mems_allowed nodemask Message-ID: <20170201085326.GE5977@dhcp22.suse.cz> References: <20170130203003.dm2ydoi3e6cbbwcj@suse.de> <20170131142237.27097-1-khandual@linux.vnet.ibm.com> <20170131160029.ubt6fvw6oh2fgxpd@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Anshuman Khandual Cc: Mel Gorman , linux-kernel@vger.kernel.org, linux-mm@kvack.org, vbabka@suse.cz, minchan@kernel.org, aneesh.kumar@linux.vnet.ibm.com, bsingharora@gmail.com, srikar@linux.vnet.ibm.com, haren@linux.vnet.ibm.com, jglisse@redhat.com, dave.hansen@intel.com, dan.j.williams@intel.com On Wed 01-02-17 13:01:24, Anshuman Khandual wrote: [...] > More importantly it also extends the cpuset memory restriction feature > to the logical completion without adding any regressions for the > existing use cases. Then why not do this ? Does it add any overhead ? Maybe it doesn't add any overhead but it just breaks the cgroups expectation that the root cgroup covers the full resource set. No cgroup controller allows to set limits on the root cgroup. So all this looks like an abuse of the interface. I haven't read the full series yet but this particular change looks like a nogo to me. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org