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=-5.3 required=3.0 tests=BAYES_00,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 2E124C433E1 for ; Mon, 17 Aug 2020 14:30:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B03E20748 for ; Mon, 17 Aug 2020 14:30:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chrisdown.name header.i=@chrisdown.name header.b="qMjHrx7t" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729023AbgHQOau (ORCPT ); Mon, 17 Aug 2020 10:30:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52930 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729012AbgHQOar (ORCPT ); Mon, 17 Aug 2020 10:30:47 -0400 Received: from mail-wr1-x443.google.com (mail-wr1-x443.google.com [IPv6:2a00:1450:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B423EC061343 for ; Mon, 17 Aug 2020 07:30:46 -0700 (PDT) Received: by mail-wr1-x443.google.com with SMTP id z18so15216774wrm.12 for ; Mon, 17 Aug 2020 07:30:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chrisdown.name; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=njqeGiWtXLg5+jOB3X5A+tJKa5oFt5uNxmm5GwqrJhw=; b=qMjHrx7t7+r44ug3VoLGOer7utNoQQG6VakgF8M2r1F1bVok4SFkN/vtuqLMQN/+jq in9MgdaZlN/g1nheeMXL0M1J7mEy0Ben0ZovQ/Es3wg1c8xsOXS9Z6p1XfiOBl273060 R5XLxrqxPBXuoAlHrseGf5+k0UeOXGw1BjnIQ= 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=njqeGiWtXLg5+jOB3X5A+tJKa5oFt5uNxmm5GwqrJhw=; b=VX9cICJjM7O58a1tGT5ZgF22xE966RBRsC+EJcYeBZL1cxxuVIY3XAVWYchVidIQmM 6jmtVscTrqoLuu9rOcDLTAn1GRiXx3+DQlUQjocTQHaxeUeopjXAmx7TOiQVspxbxshn 4tbWMT8POmsYpglfX5pi6d3UBU2EuI/H98KTHXOf5UHGDTbCKE6+ZTmvsNl9gLSm8lvU 2sqhxc6PukWD1JMftEuUO1elmORteZbKZ93tM/z+DjCye4RxJtzLWgPHYmII1M/5Kfbu obynf36KhpZUUCyU1bEYQCmLtWyIEE0cTv9V78Pb4vcgueRCq3kJTfHlykk4sFWrzff5 0DCw== X-Gm-Message-State: AOAM530yU+QmIaQbxWkGpLYmk4PwtcdLMx7Mwqn6AtujYdlSGtXNW1Cw S/LzBt2yrEjf8ECMMMYEKP/Q/w== X-Google-Smtp-Source: ABdhPJwodIZ9VzeppooFZHBp6d/RYmUjf7eNRDcmX5a3kZs1mHhE4oA9pVzsHqo4xWB+RGeWvl0HVQ== X-Received: by 2002:a5d:4d87:: with SMTP id b7mr16755889wru.170.1597674645277; Mon, 17 Aug 2020 07:30:45 -0700 (PDT) Received: from localhost ([2a01:4b00:8432:8a00:63de:dd93:20be:f460]) by smtp.gmail.com with ESMTPSA id z12sm31397694wrp.20.2020.08.17.07.30.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 17 Aug 2020 07:30:44 -0700 (PDT) Date: Mon, 17 Aug 2020 15:30:44 +0100 From: Chris Down To: Waiman Long Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Vladimir Davydov , Jonathan Corbet , Alexey Dobriyan , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH 1/8] memcg: Enable fine-grained control of over memory.high action Message-ID: <20200817143044.GA1987@chrisdown.name> References: <20200817140831.30260-1-longman@redhat.com> <20200817140831.30260-2-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20200817140831.30260-2-longman@redhat.com> User-Agent: Mutt/1.14.6 (2020-07-11) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Astractly, I think this really overcomplicates the API a lot. If these are truly generally useful (and I think that remains to be demonstrated), they should be additions to the existing API, rather than a sidestep with prctl. I also worry about some other more concrete things: 1. Doesn't this allow unprivileged applications to potentially bypass memory.high constraints set by a system administrator? 2. What's the purpose of PR_MEMACT_KILL, compared to memory.max? 3. Why add this entirely separate signal delivery path when we already have eventfd/poll/inotify support, which makes a lot more sense for modern applications?