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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id x21si6418330pll.75.2019.03.13.11.01.44 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 13 Mar 2019 11:01:44 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=PbNod2a6; spf=pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=willy@infradead.org 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) 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: 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. >