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=-0.9 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED 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 89FA6C43387 for ; Fri, 14 Dec 2018 20:17:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0622020643 for ; Fri, 14 Dec 2018 20:17:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="Fu4ippWM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730738AbeLNUR1 (ORCPT ); Fri, 14 Dec 2018 15:17:27 -0500 Received: from mail-oi1-f195.google.com ([209.85.167.195]:38751 "EHLO mail-oi1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729808AbeLNUR0 (ORCPT ); Fri, 14 Dec 2018 15:17:26 -0500 Received: by mail-oi1-f195.google.com with SMTP id a77so5589688oii.5 for ; Fri, 14 Dec 2018 12:17:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=diVL8EV9rDPgC1WMU6PlUGEMt3gqcLuSHU6zgNXCqE4=; b=Fu4ippWMUWYe2YDK3kcJh7RLuA2ktwrtXBv9zX6Hj97oLWZlOrui7Q5jbNum2otDYn JGxeWjeKNKiVcqkLpr5U4S74YPrIUxvrpK5hwMY5wTpqzlvDkCMBYWgt05lrQXGr1hFF TlQOmsZ3p0rm/q8HfiKg40x638CnNtXz/LryYS17DicC6U4fmb8NIHbp88l1U2Tjjuls 47SdSvl1YlLjYRsoo5f06ToYE7z0U3mMRKNH9xVb1qa4yp4/tBDL8H0tA4HKFd1m8TSQ SxW2b/8R/yMKkrKV34q9n0O/ckQlWe163d/AxiVzrm7aZyEbmJkHWwz7wIUNzYpBui+U AbNA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=diVL8EV9rDPgC1WMU6PlUGEMt3gqcLuSHU6zgNXCqE4=; b=GQ0oF/CP4bSb2EZsU4Kn2/QFABGe23jKjPGYIFG4IzpglTnpD54riGOfXWPM0F6FEZ cOcEJzXpiQd0jI8W/kdn6wvMF5U0sQWTdfpWH7Ne+csKDL2ZiN+9EyMJTjDLpH6KjKsu z1V17py2h9JJO5j/nXZKoQbQIYG88hZczttM4980610si51KcztBdRzFF8wXwpLnp45k W+k/8cllkstr34OqYV/wOcU6jJ6yvadhMi273+nxft8HmxQLn0ZCdxRJpoaVBzkBOrgp 9pIIZBN3HbyCPCJpDHBtcC26kowIGkhaCioF2hob0ZU7BMQhZaJ0hDpBjSVQaya5UmqI 2n/Q== X-Gm-Message-State: AA+aEWainNELixV1pdxkonT4nQ8o/ubL+MuvQmkIbY2smnkt228drPlK j7EOEznV5sRgJt2WDGRn6GpxX5c54xbYFWZu7NqKmg== X-Google-Smtp-Source: AFSGD/WECAhSWPifcO/VFFJibLUOLnhwoGe5BxZeSgZzvFFeBaze6G7XsE3a8H5WlMxbY69p3GXhVgryo6PBXpuUV4E= X-Received: by 2002:aca:2dc8:: with SMTP id t191mr2502730oit.235.1544818640988; Fri, 14 Dec 2018 12:17:20 -0800 (PST) MIME-Version: 1.0 References: <20181212150319.GA3432@redhat.com> <20181212214641.GB29416@dastard> <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> In-Reply-To: <20181214200311.GH10600@bombadil.infradead.org> From: Dan Williams Date: Fri, 14 Dec 2018 12:17:08 -0800 Message-ID: Subject: Re: [PATCH 1/2] mm: introduce put_user_page*(), placeholder versions To: Matthew Wilcox Cc: Dave Hansen , John Hubbard , david , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , 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 Content-Type: text/plain; charset="UTF-8" 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 12:03 PM Matthew Wilcox wrote: > > On Fri, Dec 14, 2018 at 11:53:31AM -0800, Dave Hansen wrote: > > On 12/14/18 11:48 AM, Matthew Wilcox wrote: > > > I think we can do better than a proxy object with bit 0 set. I'd go > > > for allocating something like this: > > > > > > struct dynamic_page { > > > struct page; > > > unsigned long vaddr; > > > unsigned long pfn; > > > ... > > > }; > > > > > > and use a bit in struct page to indicate that this is a dynamic page. > > > > That might be fun. We'd just need a fast/static and slow/dynamic path > > in page_to_pfn()/pfn_to_page(). We'd also need some kind of auxiliary > > pfn-to-page structure since we could not fit that^ structure in vmemmap[]. > > 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: df06b37ffe5a mm/gup: cache dev_pagemap while pinning pages