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=-7.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, 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 8C67BC433FE for ; Fri, 4 Dec 2020 20:23:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 230F922B40 for ; Fri, 4 Dec 2020 20:23:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728504AbgLDUX1 (ORCPT ); Fri, 4 Dec 2020 15:23:27 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:57866 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726021AbgLDUX0 (ORCPT ); Fri, 4 Dec 2020 15:23:26 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1607113320; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=rBwgpEeW4xc6+9FNssSrVJyClVzSD80HYv6Uay1hDi0=; b=BUfYQ4rnCoPBoeRjyz6lrtgdjXfBjYAiMrpdFMFTxLK6j/3hkUl4U3pMV3CcPtVmz2ZXJ2 89PDR+8xzYQLsuzX5j3qLteyIue7/vPEzCsWuIduiS0RQBCJ5GqRLtpO8HP2LM0Fic/niG BbOalFqyZVlr6ASJvn4x/mwHjerKfd0= Received: from mail-qv1-f69.google.com (mail-qv1-f69.google.com [209.85.219.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-535-P8Pm-yowM3-Mdvj1JyLNnw-1; Fri, 04 Dec 2020 15:21:58 -0500 X-MC-Unique: P8Pm-yowM3-Mdvj1JyLNnw-1 Received: by mail-qv1-f69.google.com with SMTP id y8so5717878qvu.22 for ; Fri, 04 Dec 2020 12:21:58 -0800 (PST) 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=rBwgpEeW4xc6+9FNssSrVJyClVzSD80HYv6Uay1hDi0=; b=tdKhol1yilJHRByybS5Bmrf7RSaEx0gvHk2dwQkRFwL8fRwg1IyZP/vQNA0pU4KAVe Du1glXRfngz6AVtEtqzeSJq3aSR5ZExguRpOUwXxcVhKcmAU6t0/45RQbgVK0fzzZCEl WsD/0rV/YLfL0N2CrxQI4ML5UUNRU35bK6Lsa2WyfIHPyYTRmsB1D2lQQ2SecbxdTz8A 9UZEH9GG7GvaqTwa50GjFEIk9gvb7cJCfoT29ggktqG7UBaU5o5NQFW5jWkeeoYKdfh/ Lgb4t1trSWxXfLQcSef1Xlw5cGOyVfFGdWdrsMdypbwEyNNuY50f5R0AD6z+hf3POGkN nYLQ== X-Gm-Message-State: AOAM531MswrcGstmUBcDij93Ie4v7R1T2ld8iT87wGwZ+rloZaDSaYMT HtYc4loFKSnQ7/70QF0dGvpwCZmUg8popmdE76qtABezdohb6u7vCx2wiF67g0z7yYDfZQxNRYM 42CW/WBV6AEKlxVi2CUuR1GB4 X-Received: by 2002:a05:622a:14e:: with SMTP id v14mr11003042qtw.298.1607113317891; Fri, 04 Dec 2020 12:21:57 -0800 (PST) X-Google-Smtp-Source: ABdhPJyuxHkVg57WO0rHdCyHJUi2+myd+Mny0FbYJ+FsqUJi5N6i1k+NGwIQBGkMG+vGh195cohE0w== X-Received: by 2002:a05:622a:14e:: with SMTP id v14mr11003010qtw.298.1607113317649; Fri, 04 Dec 2020 12:21:57 -0800 (PST) Received: from xz-x1 ([142.126.94.187]) by smtp.gmail.com with ESMTPSA id o4sm5836753qta.26.2020.12.04.12.21.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Dec 2020 12:21:56 -0800 (PST) Date: Fri, 4 Dec 2020 15:21:55 -0500 From: Peter Xu To: Andrea Arcangeli Cc: Hugh Dickins , Matthew Wilcox , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Mike Rapoport , David Hildenbrand Subject: Re: [PATCH v2] mm: Don't fault around userfaultfd-registered regions on reads Message-ID: <20201204202155.GQ108496@xz-x1> References: <20201202234117.GD108496@xz-x1> <20201203180234.GJ108496@xz-x1> <20201204023051.GL108496@xz-x1> <20201204192329.GP108496@xz-x1> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 04, 2020 at 02:37:17PM -0500, Andrea Arcangeli wrote: > If we use _UFFD_SWP_UFFD_WP it looks much cleaner to keep it in the > pte, not in the swp entry, since then you can use the already existing > methods that only can take in input the pte_t (not the swp_entry_t). Ah, I see now. Yes it looks nicer if we don't even need swp_entry_t knowledge to recognize the special pte. So I'll try all these ideas and update. Thanks, -- Peter Xu