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=-5.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS 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 79CCAC433DF for ; Wed, 19 Aug 2020 17:22:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B5B6206FA for ; Wed, 19 Aug 2020 17:22:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597857757; bh=ns3QqN1GE86TyATblzqVP/NCI85PrE0w52RqoEnvbBg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=0T80Xp2e6ccdo8uFsIxk/N+MGRHwK5TWv9k8jTiXD82/wgAw1OGzQT+O5ZILtNVuc CDGpbl8iXMcwo+ULvmVx7xad6Jptwjpd9m7+f7ulodvfjs3UwpS95t1ie5N0fytH0F NGhqu8wqJF+bJtNMmvvBw/viQIWnFX5WUe6mqBaA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726723AbgHSRWf (ORCPT ); Wed, 19 Aug 2020 13:22:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:57622 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726846AbgHSRWP (ORCPT ); Wed, 19 Aug 2020 13:22:15 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 757FC206FA; Wed, 19 Aug 2020 17:22:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597857734; bh=ns3QqN1GE86TyATblzqVP/NCI85PrE0w52RqoEnvbBg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=biwztO1ihUXf4Euv72Qr3Rri8ht6NKWGwsqFXckg/nbkuURUNgmIs3mw3wg/xmvKp w9LlJlTBn2g0nRd+NYSiFy0nwZv5mnv3/883shiNjSOxvRLMBKParaJI2R4PnvHTDc /AmICpbuSNWIxMgrOgeuPRS+J1+c+LrZZxUiSOoE= Date: Wed, 19 Aug 2020 10:22:14 -0700 From: Andrew Morton To: Florian Fainelli Cc: Doug Berger , Jason Baron , David Rientjes , "Kirill A. Shutemov" , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm: include CMA pages in lowmem_reserve at boot Message-Id: <20200819102214.32238093b116ab6f1c5c7b73@linux-foundation.org> In-Reply-To: References: <1597423766-27849-1-git-send-email-opendmb@gmail.com> <20200818201817.351499e75cba2a84e8bf33e6@linux-foundation.org> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 19 Aug 2020 10:15:53 -0700 Florian Fainelli wrote: > >> In many cases the difference is not significant, but for example > >> an ARM platform with 1GB of memory and the following memory layout > >> [ 0.000000] cma: Reserved 256 MiB at 0x0000000030000000 > >> [ 0.000000] Zone ranges: > >> [ 0.000000] DMA [mem 0x0000000000000000-0x000000002fffffff] > >> [ 0.000000] Normal empty > >> [ 0.000000] HighMem [mem 0x0000000030000000-0x000000003fffffff] > >> > >> would result in 0 lowmem_reserve for the DMA zone. This would allow > >> userspace to deplete the DMA zone easily. > > > > Sounds fairly serious for thos machines. Was a cc:stable considered? > > Since there is a Fixes: tag, it may have been assumed that the patch > would be picked up and as soon as it reaches Linus' tree it would be > picked up by the stable selection. It doesn't work that way - sometimes a fix isn't considered important enough to backport. It could just fix a typo in a comment!