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 5578BC433DB for ; Tue, 19 Jan 2021 23:37:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2C2E222E01 for ; Tue, 19 Jan 2021 23:37:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729007AbhASXhC (ORCPT ); Tue, 19 Jan 2021 18:37:02 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58106 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729187AbhASXgE (ORCPT ); Tue, 19 Jan 2021 18:36:04 -0500 Received: from mail-qv1-xf2d.google.com (mail-qv1-xf2d.google.com [IPv6:2607:f8b0:4864:20::f2d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D3469C0613C1 for ; Tue, 19 Jan 2021 15:35:23 -0800 (PST) Received: by mail-qv1-xf2d.google.com with SMTP id az16so10072623qvb.5 for ; Tue, 19 Jan 2021 15:35:23 -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=EhvAcZQ5rgh2MmfIZWPPX4/VupxkzFvw5zJjAClJRLQ=; b=KQP2/ghi3PyecmFsYOcygO6glPIdjbt4QD0Oum2Udyc5jCV+RO9CfcMEO5jRHIWdb1 KR55jJyCsWyHYwxbKA9AcPiyYGZhBiCRMjnz54xXKdAetGI1VBJB5ezLM1Bl452RWANG 3b35Xwdkv6mh/3cSZhpyxWCK+FayHVR6jl3HAzXsNrXEKL4ts2/9O+t+bA1DkprppOZU ny4NEb98PxfewGNh+D+qXTvBHfK5J7sWwEUvODoc+nD8BQmER8+WQHiC4nwzmBsOQTKf QAoPCzaIEKHaEiyQc9B2NrL2RGHihp7CFfbxTljqOuGbtv1hpxryOBfR/utcLZkwkrO9 Oo7w== 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=EhvAcZQ5rgh2MmfIZWPPX4/VupxkzFvw5zJjAClJRLQ=; b=pO4PAfZz8wjLzpiMlpVuENzNAvOwr0OyWWovx24sZFuJgXoimGKmaL0NSLcNKBsar2 ib1aklHSglZMjxqyCmr4juPL4ehKjO3F9AdwO4ZQA5VlWYNYvsKimCMDAHkkFgoGISHL wj7F5BofVJrg6UIbckJykysf95i+4SXJhd05QkjuV345G2VPM85MxBliAMB+JJus3lbd HOO/E/AyC+pxs2UwN9ZlYzdvZX0K+C/MgoLH9nJthvb/XtKYhtsLe8AuHM0O0HWB0lpA 528cwj1NE9aVJvI16CBnsptG3EusdpHLRSQXInDR2WrbQykdfgIwlxJL9tiSnBf1iNzn iC/g== X-Gm-Message-State: AOAM531V+l5UsrshkQElazbbvX6L6bMGZ4aQVNQu2A6bsYHWz50v7Gel cRQ5U+rEijJY3DdMQTCZ0Pvfew== X-Google-Smtp-Source: ABdhPJwQ5+FkffXGjNDuxxs8agNNaUF0vD5Ucc+XPCpjUzppX5ueLh25sKxSCYmaiwfTZk67Q0KfAw== X-Received: by 2002:a05:6214:1904:: with SMTP id er4mr6763558qvb.49.1611099323173; Tue, 19 Jan 2021 15:35:23 -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 2sm121866qtt.24.2021.01.19.15.35.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Jan 2021 15:35:22 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1l20Wv-003v6u-K8; Tue, 19 Jan 2021 19:35:21 -0400 Date: Tue, 19 Jan 2021 19:35:21 -0400 From: Jason Gunthorpe To: Pavel Tatashin Cc: LKML , linux-mm , Andrew Morton , Vlastimil Babka , Michal Hocko , David Hildenbrand , Oscar Salvador , Dan Williams , Sasha Levin , Tyler Hicks , Joonsoo Kim , mike.kravetz@oracle.com, Steven Rostedt , Ingo Molnar , Peter Zijlstra , Mel Gorman , Matthew Wilcox , David Rientjes , John Hubbard , Linux Doc Mailing List , Ira Weiny , linux-kselftest@vger.kernel.org Subject: Re: [PATCH v5 08/14] mm/gup: do not allow zero page for pinned pages Message-ID: <20210119233521.GE4605@ziepe.ca> References: <20210119043920.155044-1-pasha.tatashin@soleen.com> <20210119043920.155044-9-pasha.tatashin@soleen.com> <20210119183013.GB4605@ziepe.ca> <20210119184751.GD4605@ziepe.ca> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Tue, Jan 19, 2021 at 03:14:04PM -0500, Pavel Tatashin wrote: > I was thinking about a use case where userland would pin an address > without FOLL_WRITE, because the PTE for that address is not going to > be writable, but some device via DMA will write to it. That would be a serious bug in the get_user_pages caller to write to a page without using FOLL_WRITE Jason