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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 E5B4EC04AA8 for ; Tue, 30 Apr 2019 10:45:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A658620675 for ; Tue, 30 Apr 2019 10:45:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="bxHjCkoa" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A658620675 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1B87A6B0271; Tue, 30 Apr 2019 06:45:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1419D6B0272; Tue, 30 Apr 2019 06:45:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EFE436B0273; Tue, 30 Apr 2019 06:45:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-lj1-f200.google.com (mail-lj1-f200.google.com [209.85.208.200]) by kanga.kvack.org (Postfix) with ESMTP id 894E16B0271 for ; Tue, 30 Apr 2019 06:45:21 -0400 (EDT) Received: by mail-lj1-f200.google.com with SMTP id e9so2704665ljk.0 for ; Tue, 30 Apr 2019 03:45:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:date:from:to:cc:subject :message-id:references:mime-version:content-disposition:in-reply-to :user-agent; bh=D0Zsz5cuLJP69SdJwEsKGX6QwExtlT9EFiLTZhEUga8=; b=twbKV/4Jt7+fczZicQEjie42hp+JFXaudfyOqNPlV/QHbIKtcYnjVZ6wZpYgarJDch ywC1Lx6NHPt+aW9oA78Zj9VuOqLHdVsJCHZS21/DGn11PRhx7Se1GXQNWOwWEHXIRZ6+ p8FroU9esyyq0c3b2izvJGGeS+/GeW4OAO0jawJba3f04Ctsy6K1YkoKKq/aGSLDQnJ8 fdGJxhVbH47NtkF+wVd7ZH2qaXO0SmCMDJ3g9ThtOYmkh/K7mkdlYONtr8XXKBcM02Wg j7aPGhJGCpNf/lqHMcDTk0zjVV6mTDSnENeUJv7tuz8c8xF6yBJtRGFiHtZYB6Wv4+aM DvfA== X-Gm-Message-State: APjAAAUeZvlabIuQKEMoq2gsVYOicNpZFV5JPCAxnrCdXmY55aWQP5is HQP9djzWdjwXTzjX/dfkjSAg1tD6DNU9Ofl3L3XTim1kxsVITlKUZV+JK9G8iBG41s9XqCuAOmd K8ftBFsRrC6dhyMYrr6cvE59L3/Zbuigsg6VnfO7kE771exVVMcSKIAAN0Wdgptl8yg== X-Received: by 2002:ac2:55b2:: with SMTP id y18mr11725964lfg.133.1556621120726; Tue, 30 Apr 2019 03:45:20 -0700 (PDT) X-Received: by 2002:ac2:55b2:: with SMTP id y18mr11725904lfg.133.1556621119547; Tue, 30 Apr 2019 03:45:19 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1556621119; cv=none; d=google.com; s=arc-20160816; b=aJMKTkfjZEFiYcs5Aw+5RO+G4qBPiasDnV33EMNJK+Xt9uX/POO5NCKZklQVU1oWbL oastWRYwtfmVoBUCvGoJRnxJsXnlrLRwLGYxFG0RU8qm31+BmTS9BdmOmPXzvlBpZdGy PiWLd5GEhJfFOKfo26OVFYE4cNhSlGXImxSlLrNpDalEX/BQ8D6ezvUwqF9/kR5/q3yr BuCuYcVwLBqVk9iuc+dZa/Bv/SSnxALBtWUCYV4wja7z3lHtGmLrUVenBJUR114yBLkD OEwC8MhaL2VI95k+xTvpi716sS0NDpoxzEOera7hV1sm1YxZWGOpANWdHibDKa0C5xi6 9NtQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature; bh=D0Zsz5cuLJP69SdJwEsKGX6QwExtlT9EFiLTZhEUga8=; b=zQuPH7RSvVJFfLyQx8QwwEKtEWof+sNIp5DgHKV+qdcpMkG7gylkEJRkG5UmZvQ04G FBvxyNIcxdHIPmgNtXMYGaE8qyu5LVvIJ1XbPfePDEfI4up/JJ6RnX6zUqfTkRwOojVR zZt2TjJgfL6gl53cCSFlh5ijqI1NIAN/tutjgeZn5PX4+xAPB+w1Hz8sol+AFslsYcjz pjwn6yqDOenNg3uiIl7tNM3YecuUW9QOwCeCyNzyT4cqnKv8YnZXL4xXX/7P+68yel36 Y+Nv2B4p+d2JBtdAzLnu1MWDXi9ULwNHTIFFlbup/tbLdpr+Ibm2PJi0T6gMoUzBovMp eiYA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=bxHjCkoa; spf=pass (google.com: domain of gorcunov@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=gorcunov@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id r18sor18922579lji.31.2019.04.30.03.45.19 for (Google Transport Security); Tue, 30 Apr 2019 03:45:19 -0700 (PDT) Received-SPF: pass (google.com: domain of gorcunov@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=bxHjCkoa; spf=pass (google.com: domain of gorcunov@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=gorcunov@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=D0Zsz5cuLJP69SdJwEsKGX6QwExtlT9EFiLTZhEUga8=; b=bxHjCkoavoWP0hn9Y3zvg9uBa6/OyLqHI5jEpHTFTvFUZkg/G0SnClzHnlOncwQfd/ 8AJpSAjDKpJaytE5xuwaK8gHuPdq3EOYGTfkU0JbE7sC8Ept3JJ15+MYRxb0x6PzHfl2 AhWWFagFddh06QfYTxLFTEHlZJkd4lu28BlpyDa+VOERo0+dvzK56HWlS3dT7dUGD1DB 9lv1ZMGobUYNU9iAUHymErxAMtS8tuhcTNTsWxyb517TlnsEZ+yHZCXFmOMhDfwxEiNa rLFDeagMOuR1rkkIJHALJXo0SvmLP3t9/Vcc5XhzVX6i+qNdghV+L0LRvWzGPB3Jma5t +fXA== X-Google-Smtp-Source: APXvYqzDf7wlVV/tS0AVM5oO9IvgsP46PdHqrHNLvAfCdN4WQJCHqmCHp4cUQ7a3+BNNLwzEOz0lLA== X-Received: by 2002:a2e:3e0e:: with SMTP id l14mr35352423lja.125.1556621118804; Tue, 30 Apr 2019 03:45:18 -0700 (PDT) Received: from uranus.localdomain ([5.18.103.226]) by smtp.gmail.com with ESMTPSA id f1sm7277893ljc.73.2019.04.30.03.45.17 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 30 Apr 2019 03:45:18 -0700 (PDT) Received: by uranus.localdomain (Postfix, from userid 1000) id 68F874603CA; Tue, 30 Apr 2019 13:45:17 +0300 (MSK) Date: Tue, 30 Apr 2019 13:45:17 +0300 From: Cyrill Gorcunov To: Kirill Tkhai Cc: Michal =?iso-8859-1?Q?Koutn=FD?= , akpm@linux-foundation.org, arunks@codeaurora.org, brgl@bgdev.pl, geert+renesas@glider.be, ldufour@linux.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mguzik@redhat.com, mhocko@kernel.org, rppt@linux.ibm.com, vbabka@suse.cz Subject: Re: [PATCH 1/3] mm: get_cmdline use arg_lock instead of mmap_sem Message-ID: <20190430104517.GF2673@uranus.lan> References: <20190418182321.GJ3040@uranus.lan> <20190430081844.22597-1-mkoutny@suse.com> <20190430081844.22597-2-mkoutny@suse.com> <4c79fb09-c310-4426-68f7-8b268100359a@virtuozzo.com> <20190430093808.GD2673@uranus.lan> <1a7265fa-610b-1f2a-e55f-b3a307a39bf2@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1a7265fa-610b-1f2a-e55f-b3a307a39bf2@virtuozzo.com> User-Agent: Mutt/1.11.3 (2019-02-01) 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: On Tue, Apr 30, 2019 at 12:53:51PM +0300, Kirill Tkhai wrote: > > > > Well, strictly speaking we probably should but you know setup of > > the @arg_start by kernel's elf loader doesn't cause any side > > effects as far as I can tell (its been working this lockless > > way for years, mmap_sem is taken later in the loader code). > > Though for consistency sake we probably should set it up > > under the spinlock. > > Ok, so elf loader doesn't change these parameters. > Thanks for the explanation. It setups these parameters unconditionally. I need to revisit this moment. Technically (if only I'm not missing something obvious) we might have a race here with prctl setting up new params, but this should be harmless since most of them (except stack setup) are purely informative data.