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=-2.2 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham 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 8042EC43387 for ; Fri, 14 Dec 2018 20:29:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB9A4208C1 for ; Fri, 14 Dec 2018 20:29:41 +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="jJmdFbHM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730865AbeLNU3k (ORCPT ); Fri, 14 Dec 2018 15:29:40 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:59520 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730123AbeLNU3j (ORCPT ); Fri, 14 Dec 2018 15:29:39 -0500 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=P9Nlvot3eVP0UsJbh9RKuVypGNDsz9WelOWaZg4X9fg=; b=jJmdFbHMoOY/m/W4xqzdHf2g7 IKPvnV/nl+nRLaE4VkC4SSlABRurhQP5gcjRBRwMOu+oEC0F6WaFBbhrJmV1ODu60D5VkcmgoxKfr 1+Z13GGG7TEgUfHbkqFj+QDpBoK3NL/FPqHO1YbMuvwLwHjVYmyTL8qUJZWVJukPRJG8wNGfRPgAy kyY4/n96e8qBRhP/e4LPcdO43cXeAFVTsYCAdA8veAvW26DFXI4VrxecXULL4aroXMflTqk6x4qH8 TWhxBp3kPPjxXpttFbxBGCq1lHxsNP2musKM5h/dF6Kd+q8g3Hn65uGC9Ea1ATAlH2EJk0a/0P8Wh 5Av01Be4g==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gXu5P-0005jM-GN; Fri, 14 Dec 2018 20:29:27 +0000 Date: Fri, 14 Dec 2018 12:29:27 -0800 From: Matthew Wilcox To: Dan Williams Cc: Dave Hansen , John Hubbard , david , =?iso-8859-1?B?Suly9G1l?= Glisse , Jan Kara , John Hubbard , Andrew Morton , Linux MM , tom@talpey.com, Al Viro , benve@cisco.com, Christoph Hellwig , Christopher Lameter , "Dalessandro, Dennis" , Doug Ledford , Jason Gunthorpe , Michal Hocko , Mike Marciniszyn , rcampbell@nvidia.com, Linux Kernel Mailing List , linux-fsdevel Subject: Re: [PATCH 1/2] mm: introduce put_user_page*(), placeholder versions Message-ID: <20181214202927.GI10600@bombadil.infradead.org> References: <20181212215931.GG5037@redhat.com> <20181213005119.GD29416@dastard> <05a68829-6e6d-b766-11b4-99e1ba4bc87b@nvidia.com> <01cf4e0c-b2d6-225a-3ee9-ef0f7e53684d@nvidia.com> <20181214194843.GG10600@bombadil.infradead.org> <20181214200311.GH10600@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Fri, Dec 14, 2018 at 12:17:08PM -0800, Dan Williams wrote: > On Fri, Dec 14, 2018 at 12:03 PM Matthew Wilcox wrote: > > Yes; working on the pfn-to-page structure right now as it happens ... > > in the meantime, an XArray for it probably wouldn't be _too_ bad. > > It might... see the recent patch from Ketih responding to complaints > about get_dev_pagemap() lookup overhead: Yeah, I saw. I called xa_dump() on the pgmap_array() running under QEmu and it's truly awful because the NVDIMMs presented by QEmu are very misaligned. If we can make the NVDIMMs better aligned, we won't hit such a bad case in the XArray data structure.