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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 DE4F5C43603 for ; Mon, 9 Dec 2019 16:20:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B3D7A20692 for ; Mon, 9 Dec 2019 16:20:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="W4rrS4w8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726491AbfLIQUa (ORCPT ); Mon, 9 Dec 2019 11:20:30 -0500 Received: from mail-wm1-f42.google.com ([209.85.128.42]:32982 "EHLO mail-wm1-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725904AbfLIQUa (ORCPT ); Mon, 9 Dec 2019 11:20:30 -0500 Received: by mail-wm1-f42.google.com with SMTP id y23so259927wma.0; Mon, 09 Dec 2019 08:20:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=WBIobri3MkGop/QDs53NXiO6RTUjcrDu0iF/QcG86H0=; b=W4rrS4w8J3X0s/knW10xoM7c0XvfkfBWKTpkJv7UBseXclDelL+x9rXP7Toz7IePVV E5JzmhHlqkJIHH5mn99dwLDDvtuUF32qwp1jcmmbOYO9Vx9Xa51TZUx2qhVksqgzSF6C vkuu8dAlkddPpEADOrxVKmHQ8zrhfZi7ak47Vhg/Xektz7G4ICP9gHMA3onOstOx7DA8 Gbg3tBaeCRW879E08AF9uT1GP73T9Ro8s3Y5q2RwoPXHxALwKbg8mPZvvVOvtkaY33PM /R7quTP54GV5ANZbI5Gh2bNUwoRz/CGy5lW2XqUhfKuy0D60x5FGxD8kfBmIVJPI5Vl9 3eOw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=WBIobri3MkGop/QDs53NXiO6RTUjcrDu0iF/QcG86H0=; b=hE7kX2P7fDXb+ye04ucoAP12JmDC240Lyt3W7uEqEZw0gI2j9DV+HxLvPxUq+SBGmE +cIBDSdO2LeWUMskZymPlzY3vFIvuqIFFjK7ykoHDxukpYwixzxRD8/nYv4iYbC9PfmS EnC1S8IXBGAG0n1BqEwSdqpE6vKiRNIVInNl1KaqCzUZppSj8R4wI3B//BDeeHxywXDt /FZIkYk0hkSrCKhdXSBu4lmLmcI8nuD6YgLikBhXd8sBcvZpoXdnOgQ4kLnWhFJ0D2zL V4IoKpUEk+pjLdgIYrUoagBoGrE8xx1klUWC6wyH1/aBlaozPJ/FX9U5mnWeeMuD8xxt TuWw== X-Gm-Message-State: APjAAAWIzfSkapAplWoamI0mt5orHIfhWDR/mAqNFG3qo8wxrRLh70ks ZAwcriJV0cuLcNSNWBgswP0= X-Google-Smtp-Source: APXvYqyL3Ao5jyCATnxdfctwvZ3CBAbBWb4P4ED0mJcOmAm4L1BkpLHWjA2CTQz7JIP995Or8WFlMA== X-Received: by 2002:a7b:c38c:: with SMTP id s12mr25766920wmj.96.1575908427479; Mon, 09 Dec 2019 08:20:27 -0800 (PST) Received: from [10.68.217.182] ([217.70.210.43]) by smtp.gmail.com with ESMTPSA id n10sm27650061wrt.14.2019.12.09.08.20.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 09 Dec 2019 08:20:26 -0800 (PST) Subject: Re: [Lsf-pc] [LSF/MM TOPIC] The end of the DAX experiment To: Dan Williams , Michal Hocko Cc: lsf-pc@lists.linux-foundation.org, linux-xfs , linux-fsdevel , linux-ext4 , Linux Kernel Mailing List , linux-nvdimm References: <20190214134622.GG4525@dhcp22.suse.cz> From: Boaz Harrosh Message-ID: <5a45a763-d060-7cb1-9772-dd6e9f5f868a@gmail.com> Date: Mon, 9 Dec 2019 18:20:24 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On 14/02/2019 20:25, Dan Williams wrote: > On Thu, Feb 14, 2019 at 5:46 AM Michal Hocko wrote: >> >> On Wed 06-02-19 13:12:59, Dan Williams wrote: >> [...] >>> * Userfaultfd for file-backed mappings and DAX >> >> I assume that other topics are meant to be FS track but this one is MM, >> right? > > Yes, but I think it is the lowest priority of all the noted sub-topics > in this proposal. The DAX-reflink discussion, where a given > physical-page may need to be mapped into multiple inodes at different > offsets, might be more fruitful to have as a joint discussion with MM. > This topic is very interesting to me. In current ZUFS implementation we support this option for a long time. IE: Map same pte_t into different indexes of the same file-mappings as well as in vma(s) of different files, at different indexes. Including invalidation of mapping of a pwrite into such a shared page. (A write to a shared block will allocate a new block for writing) This effort off-course involves the participation of the FileSystem to give a list of files and indexes for map_unmapping(). I can explain if you want how we did this. Cheers Boaz