From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f69.google.com (mail-pa0-f69.google.com [209.85.220.69]) by kanga.kvack.org (Postfix) with ESMTP id 1F7866B0253 for ; Mon, 24 Oct 2016 14:00:34 -0400 (EDT) Received: by mail-pa0-f69.google.com with SMTP id yx5so2415913pac.5 for ; Mon, 24 Oct 2016 11:00:34 -0700 (PDT) Received: from mga05.intel.com (mga05.intel.com. [192.55.52.43]) by mx.google.com with ESMTPS id l78si16552857pfi.288.2016.10.24.11.00.33 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 24 Oct 2016 11:00:33 -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: Dave Hansen Message-ID: <580E4C40.50107@intel.com> Date: Mon, 24 Oct 2016 11:00:32 -0700 MIME-Version: 1.0 In-Reply-To: <580E4704.1040104@intel.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: 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, bsingharora@gmail.com On 10/24/2016 10:38 AM, 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? Urg, this is even worse than I suspected. Does this handle shared pages (like the page cache mode you call out as a requirement) where the "cdm" page is faulted into one process VMA, but it was allocated against another? Can't that give you a "cdm" page mapped into a non-VM_CDM VMA? Or, a VM_CDM VMA with no "cdm" pages in it? -- 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