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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D37F1C7618E for ; Mon, 24 Apr 2023 17:53:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232142AbjDXRxG (ORCPT ); Mon, 24 Apr 2023 13:53:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231788AbjDXRxF (ORCPT ); Mon, 24 Apr 2023 13:53:05 -0400 Received: from mail-pj1-x1029.google.com (mail-pj1-x1029.google.com [IPv6:2607:f8b0:4864:20::1029]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8041A6A42 for ; Mon, 24 Apr 2023 10:53:03 -0700 (PDT) Received: by mail-pj1-x1029.google.com with SMTP id 98e67ed59e1d1-24b29812c42so3508353a91.0 for ; Mon, 24 Apr 2023 10:53:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; t=1682358783; x=1684950783; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=0MKUvioDFym51E51dk6ySi5zEPkblTDJdgaK3QIKchw=; b=pU0zLUiEMqXNhNeDmdJkzerLQjfaVU6ziVMZ5aBW6/8vN8a4a4aaz0CGYe1VWpkXdS E3TAxastF2Qi8dfdy3CivEZaZAyEEqPau4V5u7GLpGIWazqDGhMvtqXwcOJk/18GWq9l NfYdflAXc2r5Pfs/8SKAQovKxj0V372VR5uqG12EHP3WUXy+vP1g+SEh7+pO/YgPVrGQ dPeNBCPwbJ55mq/jXw1ApR+87m2LRk772pjV+8HKvXMpUlsBub3G6yz+igtpk6UZgAfP g8+ZGHmlL+iVDIoopHyR1q0mzoLuVMgm6DEf8g3nyX83DG+CllSTCU7ZAFrebqwbyNCa gjZA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1682358783; x=1684950783; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=0MKUvioDFym51E51dk6ySi5zEPkblTDJdgaK3QIKchw=; b=ljkOduzDkXn95I9B1EC+RkNApSTz2uLN5G+QeNsIIPbjVHkK9itmXVfhCN6hvlavkH GHM4SCH97L0VEEhLvgvjCTuISdc0R2nWy9QhdgEKP1saUse0bxQONCAM5Tsnm2IxlDP2 DxjQ9KG9EWoTamputZrs7sGETKzD1QBCckcV2gOpstjKSC2c7kOCne0wD+dypY7KSIyZ 1rheZr4qUrfmDbzmAWg3aJSA0vuLSeYK+nqbUnGITKMhrJOKLAYc5Dh3No/LjizJ3B5c Mk3XR1PxiWhESnt1bKe8B6PFDaRfj/b8YAcE6+w5rOzWhgTI1a3+GCZSqVHVjEdWsx18 FGJw== X-Gm-Message-State: AAQBX9fqIs4uuq5oRYbPc9vky7V+2Utj9EIElJ836jhLVz8rV7bWge8x gC40cA/d1PKL1HIzoqBkz0VrPw== X-Google-Smtp-Source: AKy350b8QftlmzAgdTpofeaGKzAiPoEQxlMD0oxWHc4aD9JJLcqXlXiU+XTwREVgYXPzaSKrvzQzlA== X-Received: by 2002:a17:90b:1c87:b0:24b:2b9a:7fd2 with SMTP id oo7-20020a17090b1c8700b0024b2b9a7fd2mr13857171pjb.9.1682358782987; Mon, 24 Apr 2023 10:53:02 -0700 (PDT) Received: from ziepe.ca ([206.223.160.26]) by smtp.gmail.com with ESMTPSA id fs21-20020a17090af29500b002470e095920sm6824171pjb.40.2023.04.24.10.53.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Apr 2023 10:53:02 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.95) (envelope-from ) id 1pr0N2-001Vs1-FA; Mon, 24 Apr 2023 14:53:00 -0300 Date: Mon, 24 Apr 2023 14:53:00 -0300 From: Jason Gunthorpe To: Jan Kara Cc: Lorenzo Stoakes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Jens Axboe , Matthew Wilcox , Dennis Dalessandro , Leon Romanovsky , Christian Benvenuti , Nelson Escobar , Bernard Metzler , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , Bjorn Topel , Magnus Karlsson , Maciej Fijalkowski , Jonathan Lemon , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Christian Brauner , Richard Cochran , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , linux-fsdevel@vger.kernel.org, linux-perf-users@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, John Hubbard Subject: Re: [PATCH] mm/gup: disallow GUP writing to file-backed mappings by default Message-ID: References: <20230424160952.bvii2ahgxss2chev@quack3> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230424160952.bvii2ahgxss2chev@quack3> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Apr 24, 2023 at 06:09:52PM +0200, Jan Kara wrote: > So I'm maybe missing a bigger picture why we would like a change like this. > Because we still need to teach filesystems to handle pinned pages for the > usecases you don't forbid and for which we know there are users and then > what's the benefit of this patch? It immediately closes a security hole we have been talking about fixing for years already and still don't have a full fix for. An acknowledgment that this is not going to go away and starting to clamp down on the insecurity may motivate some investment in the proper fix. :) Jason