From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-f200.google.com (mail-yw0-f200.google.com [209.85.161.200]) by kanga.kvack.org (Postfix) with ESMTP id 2648F6B0260 for ; Tue, 25 Oct 2016 08:36:56 -0400 (EDT) Received: by mail-yw0-f200.google.com with SMTP id t192so10440472ywf.4 for ; Tue, 25 Oct 2016 05:36:56 -0700 (PDT) Received: from mail-pf0-x244.google.com (mail-pf0-x244.google.com. [2607:f8b0:400e:c00::244]) by mx.google.com with ESMTPS id n128si1242548itg.92.2016.10.25.05.36.55 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 25 Oct 2016 05:36:55 -0700 (PDT) Received: by mail-pf0-x244.google.com with SMTP id i85so19533679pfa.0 for ; Tue, 25 Oct 2016 05:36:55 -0700 (PDT) Subject: Re: [RFC 5/8] mm: Add new flag VM_CDM for coherent device memory References: <1477283517-2504-1-git-send-email-khandual@linux.vnet.ibm.com> <1477283517-2504-6-git-send-email-khandual@linux.vnet.ibm.com> <580E4704.1040104@intel.com> From: Balbir Singh Message-ID: <2a9819b8-0d2d-fb2a-e9d1-094f7f3cf54c@gmail.com> Date: Tue, 25 Oct 2016 23:36:34 +1100 MIME-Version: 1.0 In-Reply-To: <580E4704.1040104@intel.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen , Anshuman Khandual , linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: mhocko@suse.com, js1304@gmail.com, vbabka@suse.cz, mgorman@suse.de, minchan@kernel.org, akpm@linux-foundation.org, aneesh.kumar@linux.vnet.ibm.com On 25/10/16 04:38, Dave Hansen wrote: > On 10/23/2016 09:31 PM, Anshuman Khandual wrote: >> VMAs containing coherent device memory should be marked with VM_CDM. These >> VMAs need to be identified in various core kernel paths and this new flag >> will help in this regard. > > ... and it's sticky? So if a VMA *ever* has one of these funky pages in > it, it's stuck being VM_CDM forever? Never to be merged with other > VMAs? Never to see the light of autonuma ever again? > > What if a 100TB VMA has one page of fancy pants device memory, and the > rest normal vanilla memory? Do we really want to consider the whole > thing fancy? > Those are good review comments to improve the patchset. > This whole patch set is looking really hackish. If you want things to > be isolated from the VM, them it should probably *actually* be isolated > from the VM. As Jerome mentioned, ZONE_DEVICE is probably a better > thing to use here than to try what you're attempting. > The RFC explains the motivation, this is not fancy pants, it is regular memory from the systems perspective, with some changes as described Thanks for the review! Balbir Singh -- 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