From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753890AbeD3Kfu (ORCPT ); Mon, 30 Apr 2018 06:35:50 -0400 Received: from mail-qt0-f179.google.com ([209.85.216.179]:38601 "EHLO mail-qt0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753744AbeD3Kfq (ORCPT ); Mon, 30 Apr 2018 06:35:46 -0400 X-Google-Smtp-Source: AB8JxZq+4x/sNuh10rRxKXdOje66hA3uYMwuoON9n68RJMoegWw/SXm5ckrncBd5/1HXK3qjExu9S3iiBUvIedeMe84= MIME-Version: 1.0 In-Reply-To: <12218300.6oQjICIiUq@ferry-quad> References: <9023506.UBh6vynRGa@delfion> <1524470676.5451.1.camel@gmx.de> <20180425155459.5a4e40e0@alans-desktop> <12218300.6oQjICIiUq@ferry-quad> From: Miguel Ojeda Date: Mon, 30 Apr 2018 12:35:25 +0200 Message-ID: Subject: Re: DOS by unprivileged user To: Ferry Toth Cc: Alan Cox , Mike Galbraith , linux-kernel Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 30, 2018 at 12:00 PM, Ferry Toth wrote: > Op woensdag 25 april 2018 16:54:59 CEST schreef Alan Cox: >> > > I think memory allocation and io waits can't be decoupled from >> > > scheduling as they are now. >> > >> > The scheduler is not decoupled from either, it is intimately involved >> > in both. However, none of the decision making smarts for either reside >> > in the scheduler, nor should they. >> >> It belongs in both. >> >> Classical Unix systems never had this problem because they respond to >> thrashing by ensuring that all processes consumed CPU and made some >> progress. Linux handles it by thrashing itself to dealth while BSD always >> handled it by moving from paging more towards swapping and behaving like >> a swap bound batch machine. >> >> Linux thrashes itself to death, the classic BSD algorithn instead throws >> fairness out of the window under extreme load to prevent it. It might take >> a few seconds but at least you will get your prompt back. >> >> Alan >> > I haven t tried BSD. > > But when I was young I allocated 10MB on a HP9000 (UX) with 1MB of RAM. People wanted to launch me out of the window (18th floor). > > I did not want to say Unix was better, only with so much emphasis on security I' m surprised how easy it is for a regular user to bring linux to on it s knees. While it is true that things can be improved/tweaked for typical desktop/single user usage; this isn't really a security issue. For shared systems, there are a few ways to soft/hard limit resources: nice, *limit, cgroups, systemd limits, containers/VMs... Cheers, Miguel