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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 CF1A6C43603 for ; Sat, 21 Dec 2019 00:51:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A4AEE21655 for ; Sat, 21 Dec 2019 00:51:29 +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="pKfg9UEB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726637AbfLUAvY (ORCPT ); Fri, 20 Dec 2019 19:51:24 -0500 Received: from mail-ot1-f65.google.com ([209.85.210.65]:38447 "EHLO mail-ot1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726594AbfLUAvY (ORCPT ); Fri, 20 Dec 2019 19:51:24 -0500 Received: by mail-ot1-f65.google.com with SMTP id d7so9677942otf.5 for ; Fri, 20 Dec 2019 16:51:23 -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=f33NX0mVyrexoBKmQnsG32ndr6o8M91RbejlTLuxhxw=; b=pKfg9UEBLsx6njksUWHLBV9YCmC5Ieahekn+9soc7jLMlGZN8QDuUe3MhuCdhXgXC6 g0gDbbESs7X3oUrBExJ9JsdMsONU9A10XuSMv7r8Td92VT1lvZSJH3UfCQW1i7Y0MISg uS2PRHygg40RsyzjDa8SUbOj6VLjR2LDyqGO5Ul/NJDf/46uh1PoxGQX+YfMU/CyyhtG IsL2jFD1nFl5Z6Er0wIUYcOuiqmnJVB2yzStFIksAJDkZZdbo/uCNxgEImf+VVc9jwa2 glafhYHVftVEBCWLnGSypqNiji5kRigGyeEpI9CJW0wN6LfgAQUPFbSEuCWO48b4Xx35 0q0A== 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=f33NX0mVyrexoBKmQnsG32ndr6o8M91RbejlTLuxhxw=; b=LTUThYEH4uXdG+0lxcbd95vKS0Srl2rnedpGaJA12xwdUomosVpZpe7VoM6A2FK2cu SVmfgGPp2ZLAzQMpntAz4XpzMctv2hkuoPllm6GJrBdDBOfwEAFqvkSdAsOmz/pOSOfN vovE3NmRQ9v0rIuAEsFtOu/JSv5zOjxjkuEMR+SNYD475YmRuWqIWfwXgfzo5fN6qQtB gjWU3CpUwhHLKxEzum8IgWea5WakhasNr9liIzu2nYQ+8U1dEnIRtXQ7skoIPB0n0asO AZuoSbmQwXTgrDBY2pkJ72svIqscZkrTj1oW5dMC8JoS1/GUr8gCDid3Cx7lbylk0rl6 fw1A== X-Gm-Message-State: APjAAAX92BDu9U0CNYvpunI1sBdAhJ4vX5BQ+pujzq7wZRZahOxxd8Dt Z2UazfHoibTM+Hd853NNby4pptQ3kQaEWqJ2zRQgFA== X-Google-Smtp-Source: APXvYqxbY+fIz2rYDoZ2kDh5L9IxT6HAH53HFulCDl1AVxBdn9qKQM5q+s8gqlaKrOEYdyRgaFLwOdCutzqFOh8YHY0= X-Received: by 2002:a9d:6f11:: with SMTP id n17mr4302678otq.126.1576889483302; Fri, 20 Dec 2019 16:51:23 -0800 (PST) MIME-Version: 1.0 References: <20191216222537.491123-1-jhubbard@nvidia.com> <20191219132607.GA410823@unreal> <20191220092154.GA10068@quack2.suse.cz> <437f2bff-13ba-0ae9-2f3c-bc8eb82d20f0@nvidia.com> In-Reply-To: <437f2bff-13ba-0ae9-2f3c-bc8eb82d20f0@nvidia.com> From: Dan Williams Date: Fri, 20 Dec 2019 16:51:12 -0800 Message-ID: Subject: Re: [PATCH v11 00/25] mm/gup: track dma-pinned pages: FOLL_PIN To: John Hubbard Cc: Jan Kara , Leon Romanovsky , Andrew Morton , Al Viro , Alex Williamson , Benjamin Herrenschmidt , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , Christoph Hellwig , Daniel Vetter , Dave Chinner , David Airlie , "David S . Miller" , Ira Weiny , Jason Gunthorpe , Jens Axboe , Jonathan Corbet , =?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= , Magnus Karlsson , Mauro Carvalho Chehab , Michael Ellerman , Michal Hocko , Mike Kravetz , Paul Mackerras , Shuah Khan , Vlastimil Babka , bpf@vger.kernel.org, Maling list - DRI developers , KVM list , linux-block@vger.kernel.org, Linux Doc Mailing List , linux-fsdevel , linux-kselftest@vger.kernel.org, "Linux-media@vger.kernel.org" , linux-rdma , linuxppc-dev , Netdev , Linux MM , LKML , Maor Gottlieb Content-Type: text/plain; charset="UTF-8" Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Fri, Dec 20, 2019 at 4:41 PM John Hubbard wrote: > > On 12/20/19 4:33 PM, Dan Williams wrote: > ... > >> I believe there might be also a different solution for this: For > >> transparent huge pages, we could find a space in 'struct page' of the > >> second page in the huge page for proper pin counter and just account pins > >> there so we'd have full width of 32-bits for it. > > > > That would require THP accounting for dax pages. It is something that > > was probably going to be needed, but this would seem to force the > > issue. > > > > Thanks for mentioning that, it wasn't obvious to me yet. > > How easy is it for mere mortals outside of Intel, to set up a DAX (nvdimm?) > test setup? I'd hate to go into this without having that coverage up > and running. It's been sketchy enough as it is. :) You too can have the power of the gods for the low low price of a kernel command line parameter, or a qemu setup. Details here: https://nvdimm.wiki.kernel.org/how_to_choose_the_correct_memmap_kernel_parameter_for_pmem_on_your_system https://nvdimm.wiki.kernel.org/pmem_in_qemu