From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf1-f71.google.com (mail-lf1-f71.google.com [209.85.167.71]) by kanga.kvack.org (Postfix) with ESMTP id C48AD8E0001 for ; Fri, 11 Jan 2019 02:08:29 -0500 (EST) Received: by mail-lf1-f71.google.com with SMTP id h11so969998lfc.9 for ; Thu, 10 Jan 2019 23:08:29 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id a13-v6sor45513079ljj.25.2019.01.10.23.08.27 for (Google Transport Security); Thu, 10 Jan 2019 23:08:27 -0800 (PST) Received: from mail-lf1-f49.google.com (mail-lf1-f49.google.com. [209.85.167.49]) by smtp.gmail.com with ESMTPSA id q6sm14280660lfh.52.2019.01.10.23.08.24 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 10 Jan 2019 23:08:24 -0800 (PST) Received: by mail-lf1-f49.google.com with SMTP id c16so10076630lfj.8 for ; Thu, 10 Jan 2019 23:08:24 -0800 (PST) MIME-Version: 1.0 References: <20190109043906.GF27534@dastard> <20190110004424.GH27534@dastard> <20190110070355.GJ27534@dastard> <20190110122442.GA21216@nautica> <20190111020340.GM27534@dastard> <20190111040434.GN27534@dastard> In-Reply-To: <20190111040434.GN27534@dastard> From: Linus Torvalds Date: Thu, 10 Jan 2019 23:08:07 -0800 Message-ID: Subject: Re: [PATCH] mm/mincore: allow for making sys_mincore() privileged Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Dave Chinner Cc: Dominique Martinet , Jiri Kosina , Matthew Wilcox , Jann Horn , Andrew Morton , Greg KH , Peter Zijlstra , Michal Hocko , Linux-MM , kernel list , Linux API On Thu, Jan 10, 2019 at 8:04 PM Dave Chinner wrote: > > So it will only read the single page we tried to access and won't > perturb the rest of the message encoded into subsequent pages in > file. Dave, you're being intentionally obtuse, aren't you? It's only that single page that *matters*. That's the page that the probe reveals the status of - but it's also the page that the probe then *changes* the status of. See? Think of it as "the act of measurement changes that which is measured". And that makes the measurement pointless. Linus 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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 10829C43387 for ; Fri, 11 Jan 2019 07:08:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B9B1020870 for ; Fri, 11 Jan 2019 07:08:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="KaAhDXQQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B9B1020870 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 537338E0002; Fri, 11 Jan 2019 02:08:30 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 4BEA98E0001; Fri, 11 Jan 2019 02:08:30 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3AE618E0002; Fri, 11 Jan 2019 02:08:30 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from mail-lf1-f71.google.com (mail-lf1-f71.google.com [209.85.167.71]) by kanga.kvack.org (Postfix) with ESMTP id C48AD8E0001 for ; Fri, 11 Jan 2019 02:08:29 -0500 (EST) Received: by mail-lf1-f71.google.com with SMTP id h11so969998lfc.9 for ; Thu, 10 Jan 2019 23:08:29 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:mime-version:references :in-reply-to:from:date:message-id:subject:to:cc; bh=APfuF3eni2ygNP5lvzz/+mFQk3/YqgPBk1fCHYe99PQ=; b=bXoVdml1Uc9VyhuRmbimZ818eg+oFU5jxP/2Zhi8NT6XHxH+758gCv9Vlvxs/V4jQS QXIpQOUM1E6ic118PXTzuLpQjHSwlcufTspk+PkGwGyPewewsJVf6VN3bMBALu2vjiZx CzGpZcP4l1whQMvoCDU9/FgOwL7NoyeCI+S+FTkWZ982/0rpECRASrQX9dsXTTjeI2As 1n7gonMz/nZif6912/kuRA23kTMg8cQRMd+6r4ifBbpvUfIAkqvPvS9/fxkYgl+gcmGp DEep1hV/IC8VQobh9T2EfBF87mDuX4EzX1/N+M+xp2N9xBr8Sr6H+aOy8V5wbYK4jPRD jCGQ== X-Gm-Message-State: AJcUukd8zaeLX7DjFQBNagBpWQxeqv2VN1N/4SPdMMQm8HriSiqNIrzQ pjKKYlyCGkvVyUNsGTL4jlgxpSNbM7WlLfkh80/c/u2k0tnXBLp8DYi68cqYyBUD0sAT839fdGG rU/7quVE4TA+gN2rJnifTpuPpwIJ3U+LNYCoZsQRcbqRYdxnI9gLIVbUWf6aVUUejiZmda1PPQW 0GIoDQ6R4VOhrnq2/hfDexVFeSKhNRj7T9D/Yy1kbBLKbvQjVZLm+NFQnmjbF8G6Rs5DlN4lEkz hul+O7tPT5pWscg+14xABAgTIlED03uHu2D3tm/ceRHqhjMdB1LmtBGxb5aHtjHYmGbcJHHgnJn BPyt62Fj5LPZoYvPDlXeIFkJCdkuZcr3gkOd55LDzDT/hFeQicQHiq/+yU+ZSJSxM9qt8cjqMTU M X-Received: by 2002:a2e:b1ca:: with SMTP id e10-v6mr8588171lja.16.1547190508964; Thu, 10 Jan 2019 23:08:28 -0800 (PST) X-Received: by 2002:a2e:b1ca:: with SMTP id e10-v6mr8588119lja.16.1547190507832; Thu, 10 Jan 2019 23:08:27 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1547190507; cv=none; d=google.com; s=arc-20160816; b=z43rruUnzktiXzhCpkfAVTjZPmjalVH84d8xd4gNxas9ZCUmFcdpMHWNhqKSn/NDTo OyGw4ToFuUesGhSMNYwAfJTZmNetCnWG7wxvYtNW2kPSz315Zn4L8jyAC8t5pkzlLnj2 e2h7Ki4YfLu+kOOnbaMGlmy5A9AYMgmTHKi5ZskWh4fbdh7DyLB8vJDqsErkOIMYL3us +wzEABQk2ZZkUGGwrRiy6hgcsHtpRsNmYZB7omhnVQM4yPF6bqCiyRNsA2dHH2Yuuj0a DVmiyCP3vGMD0nku50LAu7+oxmaRsNCCzN05D0NAo/jUoo2TDNbH+TxDmpjoriu0QmFY Hxyg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:dkim-signature; bh=APfuF3eni2ygNP5lvzz/+mFQk3/YqgPBk1fCHYe99PQ=; b=Di5NCz/8nLR6Mj7o+jxDdfH0Hpfl4sYnWFtJ6GDCHD3kqM4Xefa8pAaA8DZeDhg2NJ U+Ohs66PU1KAoBfl2nHPACEQmunsyQ8Gr7jODtvTrhHvoBys1mtCjgM+kn8O981o1yYI +urB6gjMhj0ghPopzlgXoFGPE0HA4J8aAHbnGLv39ZurKkQXP4Oi6Sm02epmtLJNxYiS GxPCWsj2xsyIhBAk8FPeMqjvltLYVdNgdhyQwL442LTaliBxruNqwHFXGcWQYOduBkBi nheqT7tS/btEPwocqoUrs7fGTZ1RInGOiaVs7Gup34ek9eS97PBshzIia4stUMU0W+ZR QlLQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linux-foundation.org header.s=google header.b=KaAhDXQQ; spf=pass (google.com: domain of torvalds@linuxfoundation.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=torvalds@linuxfoundation.org Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. 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[209.85.167.49]) by smtp.gmail.com with ESMTPSA id q6sm14280660lfh.52.2019.01.10.23.08.24 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 10 Jan 2019 23:08:24 -0800 (PST) Received: by mail-lf1-f49.google.com with SMTP id c16so10076630lfj.8 for ; Thu, 10 Jan 2019 23:08:24 -0800 (PST) X-Received: by 2002:a19:6e0b:: with SMTP id j11mr7920507lfc.124.1547190503820; Thu, 10 Jan 2019 23:08:23 -0800 (PST) MIME-Version: 1.0 References: <20190109043906.GF27534@dastard> <20190110004424.GH27534@dastard> <20190110070355.GJ27534@dastard> <20190110122442.GA21216@nautica> <20190111020340.GM27534@dastard> <20190111040434.GN27534@dastard> In-Reply-To: <20190111040434.GN27534@dastard> From: Linus Torvalds Date: Thu, 10 Jan 2019 23:08:07 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] mm/mincore: allow for making sys_mincore() privileged To: Dave Chinner Cc: Dominique Martinet , Jiri Kosina , Matthew Wilcox , Jann Horn , Andrew Morton , Greg KH , Peter Zijlstra , Michal Hocko , Linux-MM , kernel list , Linux API Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Message-ID: <20190111070807.Duz9Kw44q2e-mg-WNSfzNq3oEv8jyN5jBAMa7CJuBSk@z> On Thu, Jan 10, 2019 at 8:04 PM Dave Chinner wrote: > > So it will only read the single page we tried to access and won't > perturb the rest of the message encoded into subsequent pages in > file. Dave, you're being intentionally obtuse, aren't you? It's only that single page that *matters*. That's the page that the probe reveals the status of - but it's also the page that the probe then *changes* the status of. See? Think of it as "the act of measurement changes that which is measured". And that makes the measurement pointless. Linus