Received: by 2002:a05:6a10:22f:0:0:0:0 with SMTP id 15csp3332792pxk; Mon, 5 Oct 2020 07:13:59 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwwu08IU8wxP6uZ+OoU8tJRrZmwXucGQazkLNdDoRWkrNewnxAAodI3Q8TA3wPhYLL18ie+ X-Received: by 2002:a05:6402:220f:: with SMTP id cq15mr15431393edb.24.1601907239035; Mon, 05 Oct 2020 07:13:59 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1601907239; cv=none; d=google.com; s=arc-20160816; b=ubYNN5j9l0FVHgzIZqYQrSORQ5To+hFVa2VDM7Qr9EXlXA/EJcGUbTH9WSSjC+HUSw 5Z2apQeGd5nI6O1EXDavcN4dHkYeRgt7aG3HT8yMb6bUsqRqVZah9JtTUpq6J1UNLzXR JrF+y1oZBKfQKMUh72MMuHRA2EIvu8HKx8svyeIT9+gcHuzJrwI5SZ7Zf2L0JIaiAy+7 UaaYCA2NDd4F9AMrzTwoEzGPLasW7qsTV8+l6B4/3Hb+s/LoUtCaRMMFTDNmyn9WrCx4 92B5LzlV7wZNlMwE01Qxti+AUjDDQkJjIaAol6Izsq/8djpIAyTvGxHN5FAYX/lCilop eM/A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :organization:references:in-reply-to:message-id:subject:cc:to:from :date; bh=R0f/etpBgZ2p+mKYrnfQZoXDN9ohO1AalBGfJoiedc0=; b=LonHPhdU3VpW5XSGsmeXmgC7xGMLdWSdX9xgHUQ/IzJWcRneE4Hhh0Mfl39zgu07LT PvESQtyD6KmqO2ay0rUBGBzuWtG1aIThRsLuYXAFNH8uUyi5O/sVMWMU3xll7E8KKLO2 z/gu+rqSaYBrkVH+LctoHe/OdRIICdrhO/dmNUrGtjmDPNYpBzhWHKHndcbnrF44Mosi H6UoIo6u8j5xK11DLJ3KYz2DFecT8XS6HMVN+T9zLscTaDYZf88uZbKdbli/oQPTylWk fZqYv6RBvaM4qKzhLaeeUQ6gZolPnYMTzOkcCABx7xlF393M23VbdIYFGfLm3twYZlXB dBmQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id j22si27952edy.100.2020.10.05.07.13.34; Mon, 05 Oct 2020 07:13:59 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725981AbgJEOMO (ORCPT + 99 others); Mon, 5 Oct 2020 10:12:14 -0400 Received: from ms.lwn.net ([45.79.88.28]:47794 "EHLO ms.lwn.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725903AbgJEOMO (ORCPT ); Mon, 5 Oct 2020 10:12:14 -0400 Received: from lwn.net (localhost [127.0.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ms.lwn.net (Postfix) with ESMTPSA id 423A32E4; Mon, 5 Oct 2020 14:12:12 +0000 (UTC) Date: Mon, 5 Oct 2020 08:12:10 -0600 From: Jonathan Corbet To: Topi Miettinen Cc: Michal Hocko , David Hildenbrand , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: optionally disable brk() Message-ID: <20201005081210.2231e552@lwn.net> In-Reply-To: <7d7b1ac5-d6a7-5e43-8fb8-12b844d7f501@gmail.com> References: <20201002171921.3053-1-toiwoton@gmail.com> <653873ef-2a57-37e0-1ac3-fba763652b35@redhat.com> <2a0f5ade-d770-c36e-50bc-ff0c8e9dacbf@gmail.com> <20201005061248.GN4555@dhcp22.suse.cz> <7d7b1ac5-d6a7-5e43-8fb8-12b844d7f501@gmail.com> Organization: LWN.net MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 5 Oct 2020 11:11:35 +0300 Topi Miettinen wrote: > The point is not to shrink the kernel (it will shrink by one small > function) or get rid of complexity. The point is to disable an inferior > interface. Memory returned by mmap() is at a random location but with > brk() it is located near the data segment, so the address is more easily > predictable. So if your true objective is to get glibc to allocate memory differently, perhaps the right thing to do is to patch glibc? Thanks, jon