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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 595AAC433E0 for ; Tue, 16 Jun 2020 13:47:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3828620A8B for ; Tue, 16 Jun 2020 13:47:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=arista.com header.i=@arista.com header.b="U6/hmvvb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728969AbgFPNrw (ORCPT ); Tue, 16 Jun 2020 09:47:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56076 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726306AbgFPNrv (ORCPT ); Tue, 16 Jun 2020 09:47:51 -0400 Received: from mail-pj1-x1041.google.com (mail-pj1-x1041.google.com [IPv6:2607:f8b0:4864:20::1041]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8B652C061573 for ; Tue, 16 Jun 2020 06:47:51 -0700 (PDT) Received: by mail-pj1-x1041.google.com with SMTP id i12so1471215pju.3 for ; Tue, 16 Jun 2020 06:47:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=googlenew; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=TUln3eDvcCJnsTxP4o2nCcbHN366GT2XubrxAw/PwPQ=; b=U6/hmvvbBbi9/FmqWEyN7ARc+R7Qqp9XN3x/VwhFJBb4m2JgiRW7JX/moBz4mnQgZm WPlOUeu+0igHuD55YwEruLd1450HsTM1F0FBQ7ShKl8YTQsser8xdFrstxqNSMRYlPNl ZHjjjEYU/uC0c17FfWG0iljqCjCV+68N/ZbFe4w7wsTgIUtVxTIcHLGZq8nKyqMAh2cP GO4lbPVN1quzQkJulkGhxhz4pTvLLjqr3MA882ZhK3jTb66EMyR1yBvsowZ0hY97mIy1 k3e7T/NBrnzQks5Z+2r8aCGXg4Cs+sfJ00+ZdD85ZaEjeSUMpLhcnGJaqAA9SFu2ernE WNRw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=TUln3eDvcCJnsTxP4o2nCcbHN366GT2XubrxAw/PwPQ=; b=FdLrb+fzrMfGZEuaBzY9Bl1EbzlszpR/Yz/CSGa6Z1Yeues3MQmV22fe0RO4thyLEN uFs9ou/1LpB2+0dOTzAP6tYO6qHsMKjkx7ovhj/l1wCn4qEd9CkdBRkUYjWyhcTDvng1 6PB2Uwk0zuyeYAQhaeoG/QT5G5vZ14scq3JuQZFMqtkES0sofLTGZe3Vv6HB8XK7R3sC 7kTZr+ZRl9L0zMDZDLK9HJJ6xix3UO/1DOi5gXb4XnIoQrbc6oz3hbNlnBjS5rL18XFu FCGBsceSGbRI7Y8x5LyXgt75sLO0L2P2xRUVLalNbjB5m8ZL7ks1U6Bqvbu2phw/FwpN S88w== X-Gm-Message-State: AOAM533rjIudXF67W6z3bPpsoQq2m3kzdWvEAIake3+x0y3HApN8ZYUo ytP1NizrygNoUaVsfTMPquJTMA== X-Google-Smtp-Source: ABdhPJwh0ibun0ESRx+TqhgJ9AGgABOCSZFvigx9X6GzGraON4S2C0XpvGXtaFdBeNA6eAekB/neHg== X-Received: by 2002:a17:902:9b92:: with SMTP id y18mr2057706plp.228.1592315270891; Tue, 16 Jun 2020 06:47:50 -0700 (PDT) Received: from ?IPv6:2a02:8084:e84:2480:228:f8ff:fe6f:83a8? ([2a02:8084:e84:2480:228:f8ff:fe6f:83a8]) by smtp.gmail.com with ESMTPSA id k12sm17030398pfk.219.2020.06.16.06.47.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 16 Jun 2020 06:47:50 -0700 (PDT) Subject: Re: [PATCH 2/6] arm64/vdso: Zap vvar pages when switching to a time namespace To: Mark Rutland , Andrei Vagin Cc: linux-arm-kernel@lists.infradead.org, Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, Vincenzo Frascino , Thomas Gleixner References: <20200616075545.312684-1-avagin@gmail.com> <20200616075545.312684-3-avagin@gmail.com> <20200616112418.GC11780@C02TD0UTHF1T.local> From: Dmitry Safonov Message-ID: Date: Tue, 16 Jun 2020 14:47:46 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200616112418.GC11780@C02TD0UTHF1T.local> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mark, On 6/16/20 12:24 PM, Mark Rutland wrote: > On Tue, Jun 16, 2020 at 12:55:41AM -0700, Andrei Vagin wrote: [..] >> Whenever a task changes its namespace, the VVAR >> page tables are cleared and then they will be re-faulted with a >> corresponding layout. > > How does this work for multi-threaded applications? Are there any > concerns w.r.t. atomicity of the change? Multi-threaded applications can't setns() for time namespace, timens_install(): : if (!current_is_single_threaded()) : return -EUSERS; Thanks, Dmitry