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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 873F6C433E0 for ; Mon, 8 Feb 2021 23:27:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4F32664E7A for ; Mon, 8 Feb 2021 23:27:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230408AbhBHX1L (ORCPT ); Mon, 8 Feb 2021 18:27:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229751AbhBHX1H (ORCPT ); Mon, 8 Feb 2021 18:27:07 -0500 Received: from mail-qk1-x729.google.com (mail-qk1-x729.google.com [IPv6:2607:f8b0:4864:20::729]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7E568C061786 for ; Mon, 8 Feb 2021 15:26:27 -0800 (PST) Received: by mail-qk1-x729.google.com with SMTP id q85so4030576qke.8 for ; Mon, 08 Feb 2021 15:26:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=tPs7Rxd3+a1J4EcPtbp92Vc8SIRVzBfN6f0oIsK/9dE=; b=NGjt6irEWGzDe4R0vuCTGyrQtyj+Lqew2oddL9qXYYkTZi3hhtyG5TI8KRmoHku4Z6 I/rDjvOu8LBsGkR/eDbnCjg+qzHLR5uL/lXzqVJBJWF7lTbDTTQnj31VWRcSSU38XJkF ZUXv2uerrPTteSPfpP/x7KBNkFNj34yXvDcbiUUJYe0CUwRKgxgPkWOYY+ixLlzPM+pG o08Os9fzu3jVp0yHonS5lYnDKycpicZDlNKLfkRCkp4Yc49CG/S+p/hSK0+Jdic42+BD FurImZvpISN/hhX+vEsJWpBVYY+XEF9zHrkBXlAuQkqpqhZvPqw2LoE8i2sMKsC9yd1i i34A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=tPs7Rxd3+a1J4EcPtbp92Vc8SIRVzBfN6f0oIsK/9dE=; b=t9Uwjr0hI/79CeXqk06cf/F4z05mG9gp1/vOf7g3yTviEpqK5xsYN2/W7P4/jWSaBs S6yeHERjpwhPx4+w8hPRvSsKRg9y3+YvXIXSz3zHNT23r0DV/gnKiyoY/DC+3rCWk3wv bwmnkaxpTlV83kd8wsUbBe5lAec3NRwUxJr77c9h7aYHpSbRl9sl37/w1OfygIYxPD8i Doskt1x6hi4pnPOxOTnPOcW1ZoM9PpVQQfBnTQvW7iBNMWlqBmv7YVPWQ6/1HqJ76Gn8 G91eAt13ch2igM2lC66gi9HYioKcA/aWhcqHCp6iL6Iggdk/VHtSHcmbMVPQlofnqjo/ a3HQ== X-Gm-Message-State: AOAM531dAvRALXczS813MdQwfIqZnaJyu3X27yRlefyKYPiB4nZiAD9y eXiF0vw/KCDGC6kJU0zT1Gdwqg== X-Google-Smtp-Source: ABdhPJwSgIbUiF0xJm2keLZ0APQp0Ru6baflVBIy955ENsWj4a1eAmS+5rWyR/uRtttw/vmjx7myMQ== X-Received: by 2002:a05:620a:5fa:: with SMTP id z26mr19500613qkg.108.1612826786830; Mon, 08 Feb 2021 15:26:26 -0800 (PST) Received: from ziepe.ca (hlfxns017vw-142-162-115-133.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.115.133]) by smtp.gmail.com with ESMTPSA id q55sm2537411qtq.57.2021.02.08.15.26.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Feb 2021 15:26:26 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1l9FvF-0057WX-GA; Mon, 08 Feb 2021 19:26:25 -0400 Date: Mon, 8 Feb 2021 19:26:25 -0400 From: Jason Gunthorpe To: Peter Xu Cc: dan.j.williams@intel.com, Paolo Bonzini , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, Andrew Morton Subject: Re: [PATCH 0/2] KVM: do not assume PTE is writable after follow_pfn Message-ID: <20210208232625.GA4718@ziepe.ca> References: <20210205103259.42866-1-pbonzini@redhat.com> <20210205181411.GB3195@xz-x1> <20210208185133.GW4718@ziepe.ca> <20210208220259.GA71523@xz-x1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210208220259.GA71523@xz-x1> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 08, 2021 at 05:02:59PM -0500, Peter Xu wrote: > On Mon, Feb 08, 2021 at 02:51:33PM -0400, Jason Gunthorpe wrote: > > On Fri, Feb 05, 2021 at 01:14:11PM -0500, Peter Xu wrote: > > > > > But I do have a question on why dax as the only user needs to pass in the > > > notifier to follow_pte() for initialization. > > > > Not sure either, why does DAX opencode something very much like > > page_mkclean() with dax_entry_mkclean()? > > > > Also it looks like DAX uses the wrong notifier, it calls > > MMU_NOTIFY_CLEAR but page_mkclean_one() uses > > MMU_NOTIFY_PROTECTION_PAGE for the same PTE modification sequence?? > > > > page_mkclean() has some technique to make the notifier have the right > > size without becoming entangled in the PTL locks.. > > Right. I guess it's because dax doesn't have "struct page*" on the > back, so it It doesn't? I thought DAX cases did? Jason