From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A24DCC10F03 for ; Wed, 13 Mar 2019 18:01:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6AF552177E for ; Wed, 13 Mar 2019 18:01:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="PbNod2a6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726974AbfCMSBp (ORCPT ); Wed, 13 Mar 2019 14:01:45 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:33338 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726446AbfCMSBp (ORCPT ); Wed, 13 Mar 2019 14:01:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=FLtnEhcZitgPrumTgx6A1mOi4wgkfJ/JfwJzueYQV10=; b=PbNod2a6s0twimut9yz4LCuuG 3Gkxl2AugBv1zrAJBE2wrCq/aw6tUjEciElAs2Nv0Z88sh1Eed8kxDyRCrbrsEAS+LiA2gUwSBmyH bZTbGpAx15k1rx6tkVKl0aLfnwJrWMKAmJh5GZaAWI5QGFY+Dks2ss7DT1cFoEHodWNH7MWUFi3XF eFPenKgy/SJSph/gqVQlBkszagqB7svzNjQy5Mt5XYtTCbE/svYZQfC6KtBBhAjbcKDUNN+Tto4HN h7VSmL9pOJFpT4QT2e6gaU7/owcrnfk9q59XmTbDltmoJRJ1KMEiryCyzNUtMMnGptq5rY6WqZzWo SDddJUKgg==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1h48CF-0005k5-Cu; Wed, 13 Mar 2019 18:01:43 +0000 Date: Wed, 13 Mar 2019 11:01:43 -0700 From: Matthew Wilcox To: Laurent Dufour Cc: lsf-pc@lists.linux-foundation.org, Linux-MM , linux-kernel@vger.kernel.org, "Liam R. Howlett" Subject: Re: [LSF/MM TOPIC] Using XArray to manage the VMA Message-ID: <20190313180142.GK19508@bombadil.infradead.org> References: <7da20892-f92a-68d8-4804-c72c1cb0d090@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7da20892-f92a-68d8-4804-c72c1cb0d090@linux.ibm.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. >