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 B6597C4332D for ; Mon, 8 Feb 2021 20:17:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9080D64E7A for ; Mon, 8 Feb 2021 20:17:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236818AbhBHUR4 (ORCPT ); Mon, 8 Feb 2021 15:17:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42904 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235833AbhBHSwQ (ORCPT ); Mon, 8 Feb 2021 13:52:16 -0500 Received: from mail-qk1-x730.google.com (mail-qk1-x730.google.com [IPv6:2607:f8b0:4864:20::730]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 03FEEC061788 for ; Mon, 8 Feb 2021 10:51:34 -0800 (PST) Received: by mail-qk1-x730.google.com with SMTP id b14so1928774qkk.0 for ; Mon, 08 Feb 2021 10:51:34 -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=FREB4k4pL+/EwQVi/jq4eIfgwfGwgd8/O2V49WmG3yI=; b=ayKBiVUeDmZgutOHEL4vMvTvHca+pVKQbcb658vawwG09uauE5m3ic5gN6c9JkzeTX HGjYLobolsvKN/n9h49zmwT9Nf+FhGtdx+spz++X3Q0NB3znozLYOu+Qdt8ShcpBJ7gJ Wgoe4nJSIHNuvgGHCdn9+HAGCM3L8K90nEXC7tOC9Ht1wLXziklRqWIiN7+njvhCJxGV u8wDnYz+fsyNBQKkwR8jDwcXvXBHHeXX/L28GBohrBDWsLiCtakt8qbuEYDTbHafl2NP jN6MmoSdE5Gryh2iz+rHB+pGMoQ2Q/eY5JpUSeBnyruSNGaJ1wjwA5t8B4qAF5p52D2d jb5A== 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=FREB4k4pL+/EwQVi/jq4eIfgwfGwgd8/O2V49WmG3yI=; b=N4t8/eVBeNTT2jHl7CafGaVGIBfQEPcNhV5kUq66cKMqrvP3zCd4zAb4YLXMinPjH0 3zZyzfoOMMIkn5m8WNKnn4zaJrLTgLa3YoD7xYdDiHzOpL8MPP97zuFWxC9nb2F66AFu JBiEek4n9/iODfcZUDkHl2gR2vY89Zmdq05W71TwPiGBsaNHkmFTRX5Mj09QdY20Z393 H95ic2cKr4srL3/26EdZZQ0YEmA/inXlSDLJGF2YBe2j3vAhiPMo4GzprQWDeBI6ae4Q BHpLqXpFadd1GAZC8nhe/4sJI6cmU78wwzpg3cMWtZJNO9RTfJqt58JTGszuaGDy/KPH WEXQ== X-Gm-Message-State: AOAM53317i+NrWYgitDpDFxGuPCqCRlEQ3l/M6pLcNaHRnimyOR4gKYt gfX/OlQb6fWcd3Y7w3Zbd0lDdA== X-Google-Smtp-Source: ABdhPJyWgaNBTCVawkQVPK0b06TB5cBGj1xy2Hg+/c/xFkZeuj/u1FCWtQfIhSeg/PKdKxAppdWkGg== X-Received: by 2002:a37:5905:: with SMTP id n5mr18045893qkb.191.1612810294198; Mon, 08 Feb 2021 10:51:34 -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 w188sm17159979qkc.19.2021.02.08.10.51.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Feb 2021 10:51:33 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1l9BdF-0052Tc-8p; Mon, 08 Feb 2021 14:51:33 -0400 Date: Mon, 8 Feb 2021 14:51:33 -0400 From: Jason Gunthorpe To: Peter Xu , dan.j.williams@intel.com Cc: 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: <20210208185133.GW4718@ziepe.ca> References: <20210205103259.42866-1-pbonzini@redhat.com> <20210205181411.GB3195@xz-x1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210205181411.GB3195@xz-x1> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.. Jason