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 38AAEC432BE for ; Fri, 27 Aug 2021 12:10:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1DB0860F6C for ; Fri, 27 Aug 2021 12:10:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245092AbhH0ML0 (ORCPT ); Fri, 27 Aug 2021 08:11:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45462 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245011AbhH0MLZ (ORCPT ); Fri, 27 Aug 2021 08:11:25 -0400 Received: from mail-qk1-x72f.google.com (mail-qk1-x72f.google.com [IPv6:2607:f8b0:4864:20::72f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65263C0613CF for ; Fri, 27 Aug 2021 05:10:36 -0700 (PDT) Received: by mail-qk1-x72f.google.com with SMTP id p4so550845qki.3 for ; Fri, 27 Aug 2021 05:10:36 -0700 (PDT) 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=tabyB924yXzKjpImGrZhEjdKF7M150xI6NXPXiRzacQ=; b=BXOWR0PoIMXAKeleGwpfna7bI0eKjcWwgsphSW8ThLvagIpDr0ls8T2rwQF4WaCYAP Nq8VthgBIjaMUmNkJJE5Hwe0p/+3AElNMwCti8WYko1Ip355vTLK41xamz4sDzkVarCy TuTYufAPQjwnsjTbjgE8ZUjjOE4nIIg6xWTi5I0b8whsNLyXTuNpMRqj7m25O1m/kjyi tGleiN1YawmdwDRDS6nIrbww73nh546jFUpBOYpQ8ryhiIH/GPQxhlfqdnkbPU9jgudD udg/fSkl8CvxxWVRbSd6JBto62jmSLZwL21/ci7CBLE9os8UXBW4oIz1k3angsHEHn8J OzjA== 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=tabyB924yXzKjpImGrZhEjdKF7M150xI6NXPXiRzacQ=; b=WZmj2UxCwEKh1rZ0OlFOvoKbhTb5LonXKYnsNyqZEIbNuwEUrPAUVVxASQL2UuybfV 8Wi3X+E4/X+UdT3k0rcCI6VIgShFZBZbCndaXHOaGyqyUTZZ9JwGz9zEZc975uEYiC1s rFI/ZRyw0YK/5R0xgDkmQvtujJq0q+YRBO5bIQYaSuV4sWibV4obRvoyeaDVuBYoibL6 Tws/Jb7SQsOllVSBl6/KqKpQocXhRMOYFKquwzwIATunQXdKxQnWxopf1dEOvgl5aeiI MzQo8WAqqnMPvaTzlBxprBic25GwYUKKl6rYScVfJYTdJsQk5yechT1yd0Jx5v/bE8ST GDzQ== X-Gm-Message-State: AOAM530TGg5NDNlJP3ezN6N70paHourKmy2aAj+qSo/E8zwPLMCoJ3JW iT/RcrJZ7aHOhsuZrfPiplgoiw== X-Google-Smtp-Source: ABdhPJxcPlkQBE/+4Tx66G5euuWsIpG7RqUHiGHzvkWM9wne3DI0N4maWU6ebpmyWqNselqD09P/QQ== X-Received: by 2002:a05:620a:7d5:: with SMTP id 21mr8703422qkb.339.1630066235609; Fri, 27 Aug 2021 05:10:35 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-142-162-113-129.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.113.129]) by smtp.gmail.com with ESMTPSA id b1sm3451778qtj.76.2021.08.27.05.10.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Aug 2021 05:10:35 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1mJags-005eR4-H7; Fri, 27 Aug 2021 09:10:34 -0300 Date: Fri, 27 Aug 2021 09:10:34 -0300 From: Jason Gunthorpe To: "lizhijian@fujitsu.com" Cc: "nvdimm@lists.linux.dev" , Yishai Hadas , "linux-rdma@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "yangx.jy@fujitsu.com" Subject: Re: RDMA/rpma + fsdax(ext4) was broken since 36f30e486d Message-ID: <20210827121034.GG1200268@ziepe.ca> References: <8b2514bb-1d4b-48bb-a666-85e6804fbac0@cn.fujitsu.com> <68169bc5-075f-8260-eedc-80fdf4b0accd@cn.fujitsu.com> <20210806014559.GM543798@ziepe.ca> <10c4bead-c778-8794-f916-80bf7ba3a56b@fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <10c4bead-c778-8794-f916-80bf7ba3a56b@fujitsu.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 27, 2021 at 08:15:40AM +0000, lizhijian@fujitsu.com wrote: > i looked over the change-log of hmm_vma_handle_pte(), and found that before > 4055062 ("mm/hmm: add missing call to hmm_pte_need_fault in HMM_PFN_SPECIAL handling") > > hmm_vma_handle_pte() will not check pte_special(pte) if pte_devmap(pte) is true. > > when we reached > "if (pte_special(pte) && !is_zero_pfn(pte_pfn(pte))) {" > the pte have already presented and its pte's flag already fulfilled the request flags. > > > My question is that > Per https://01.org/blogs/dave/2020/linux-consumption-x86-page-table-bits, > pte_devmap(pte) and pte_special(pte) could be both true in fsdax user case, right ? How? what code creates that? I see: insert_pfn(): /* Ok, finally just insert the thing.. */ if (pfn_t_devmap(pfn)) entry = pte_mkdevmap(pfn_t_pte(pfn, prot)); else entry = pte_mkspecial(pfn_t_pte(pfn, prot)); So what code path ends up setting both bits? Jason