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[148.163.156.1]) by mx.google.com with ESMTPS id 32si1505044plc.427.2019.03.29.02.31.56 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 29 Mar 2019 02:31:56 -0700 (PDT) Received-SPF: pass (google.com: domain of ldufour@linux.ibm.com designates 148.163.156.1 as permitted sender) client-ip=148.163.156.1; Authentication-Results: mx.google.com; spf=pass (google.com: domain of ldufour@linux.ibm.com designates 148.163.156.1 as permitted sender) smtp.mailfrom=ldufour@linux.ibm.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=ibm.com Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x2T9OJsS127387 for ; Fri, 29 Mar 2019 05:31:56 -0400 Received: from e06smtp07.uk.ibm.com (e06smtp07.uk.ibm.com [195.75.94.103]) by mx0a-001b2d01.pphosted.com with ESMTP id 2rhecjr7kt-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Fri, 29 Mar 2019 05:31:56 -0400 Received: from localhost by e06smtp07.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 29 Mar 2019 09:31:50 -0000 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x2T9VnMG41746662 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 29 Mar 2019 09:31:49 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 49BC5A4062; Fri, 29 Mar 2019 09:31:49 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E5D7CA4060; Fri, 29 Mar 2019 09:31:47 +0000 (GMT) Received: from [9.145.61.64] (unknown [9.145.61.64]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 29 Mar 2019 09:31:47 +0000 (GMT) Subject: Re: [LSF/MM TOPIC] Using XArray to manage the VMA To: Matthew Wilcox , Michel Lespinasse , David Rientjes Cc: lsf-pc@lists.linux-foundation.org, Linux-MM , linux-kernel@vger.kernel.org, "Liam R. Howlett" References: <7da20892-f92a-68d8-4804-c72c1cb0d090@linux.ibm.com> <20190313180142.GK19508@bombadil.infradead.org> From: Laurent Dufour Date: Fri, 29 Mar 2019 10:31:45 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.6.0 MIME-Version: 1.0 In-Reply-To: <20190313180142.GK19508@bombadil.infradead.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 19032909-0028-0000-0000-00000359ECAD X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19032909-0029-0000-0000-00002418B0C3 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-03-29_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903290069 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: Adding Michel and David in the loop who are interested in this topic too. Le 13/03/2019 à 19:01, Matthew Wilcox a écrit : > On Wed, Mar 13, 2019 at 04:10:14PM +0100, Laurent Dufour wrote: >> If this is not too late and if there is still place available, I would like >> to attend the MM track and propose a topic about using the XArray to replace >> the VMA's RB tree and list. > > If there isn't room on the schedule, then Laurent and I are definitely > going to sneak off and talk about this ourselves at some point. Having a > high-bandwidth conversation about this is going to be really important > for us, and I think having other people involved would be good. > > If there're still spots, it'd be good to have Liam Howlett join us. > He's doing the actual writing-of-code for the Maple Tree at the moment > (I did some earlier on, but recent commits are all him). > >> Using the XArray in place of the VMA's tree and list seems to be a first >> step to the long way of removing/replacing the mmap_sem. >> However, there are still corner cases to address like the VMA splitting and >> merging which may raise some issue. Using the XArray's specifying locking >> would not be enough to handle the memory management, and additional fine >> grain locking like a per VMA one could be studied, leading to further >> discussion about the merging of the VMA. >> >> In addition, here are some topics I'm interested in: >> - Test cases to choose for demonstrating mm features or fixing mm bugs >> proposed by Balbir Singh >> - mm documentation proposed by Mike Rapoport >> >> Laurent. >> >