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 920E2C43219 for ; Tue, 30 Apr 2019 09:38:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5C02021670 for ; Tue, 30 Apr 2019 09:38:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ukGEBlNW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727081AbfD3JiM (ORCPT ); Tue, 30 Apr 2019 05:38:12 -0400 Received: from mail-lj1-f193.google.com ([209.85.208.193]:46228 "EHLO mail-lj1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726129AbfD3JiM (ORCPT ); Tue, 30 Apr 2019 05:38:12 -0400 Received: by mail-lj1-f193.google.com with SMTP id h21so12084958ljk.13 for ; Tue, 30 Apr 2019 02:38:10 -0700 (PDT) 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=zYjnml+G09Y2iH7YOBy1RnUmEBfOtgqF9A/Rh/pjRIY=; b=ukGEBlNWpw3ngsxHEBXIQvlOeQhk4/p8R6GklmoB2a/Xv4c2NAwqOW+cNq7yBLyL2B dBM9smuHxp7kZy66IxNEH6kzgwI4RJd82xvidtZDKhUdNbLaEsENurzJ+oj57ObbDtPs 2gPE4aJopsgxoW0EJ3MNExq6DgBsaZ+Kv6Jfluqf0CtBIn88GNQzHCmQolL80H1brM2K yijxEgwd99V9DqOpzUHXvBwaNvpoxs9k9tTcEX9MRgfaanxEYssrdayZTUb/xuilfH7/ y9GV0XIkScDJQx2nQUJrqtsIXjr2x18uJzzzUjE/TilqtUizxTCPjBmxTC6/AOgrlhFc HKig== 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:user-agent; bh=zYjnml+G09Y2iH7YOBy1RnUmEBfOtgqF9A/Rh/pjRIY=; b=oA8rZ3PBj06sSA8s3hBgKX35s1u//j9t2mdi8WBxvBZbKcVG8WqjYHi3vqkFOXvJ4H cYPHTeMyFEdMmzXUSd0OuEr66OdZ7kxgC8EBRCKZOKByWSRupbJzVYW9Zp+rpXnvj42D Sm0qsl10YicI1ReeTa3Rv804AJ9noQQnPa5+w69BNcZbLL9xq2pFCJvfFMZgPcCn/FGM dcImPFk2/gSjBaT5ShtXl0tcxaZTF3SX3sSWpc1J6aMCGM4Rl/DhXH/AMwjVRAtIVUmy K8TXNa74b4gLyyZr4o3OdtQP3NTp/WCy3CRqBShepihlxZSjS6wusnRZFI1Toaio6pbN aBWw== X-Gm-Message-State: APjAAAUhxMieGq2E5TVCc35Ki6Y2f/QIO4GBxZ4oILhosX4ZtDPvyNwx VyjrVcuQ2/KQIrOMbPqrAwY= X-Google-Smtp-Source: APXvYqxOGwnTEPiPGzR1pnewgUsAD0rmNHah8NK5uqndt/a8Ai7cN9+BqLVfK2dgtlDwZGL1HRdMqw== X-Received: by 2002:a2e:8648:: with SMTP id i8mr36897627ljj.166.1556617090058; Tue, 30 Apr 2019 02:38:10 -0700 (PDT) Received: from uranus.localdomain ([5.18.103.226]) by smtp.gmail.com with ESMTPSA id l16sm7876890lfk.44.2019.04.30.02.38.08 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 30 Apr 2019 02:38:09 -0700 (PDT) Received: by uranus.localdomain (Postfix, from userid 1000) id 840A24603CA; Tue, 30 Apr 2019 12:38:08 +0300 (MSK) Date: Tue, 30 Apr 2019 12:38:08 +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: <20190430093808.GD2673@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4c79fb09-c310-4426-68f7-8b268100359a@virtuozzo.com> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 30, 2019 at 12:09:57PM +0300, Kirill Tkhai wrote: > > This looks OK for me. > > But speaking about existing code it's a secret for me, why we ignore arg_lock > in binfmt code, e.g. in load_elf_binary(). 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.