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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AF266C433F5 for ; Thu, 24 Feb 2022 06:33:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230178AbiBXGeF (ORCPT ); Thu, 24 Feb 2022 01:34:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229838AbiBXGeE (ORCPT ); Thu, 24 Feb 2022 01:34:04 -0500 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1CC89AC915; Wed, 23 Feb 2022 22:33:35 -0800 (PST) Received: by verein.lst.de (Postfix, from userid 2407) id 3C97768AA6; Thu, 24 Feb 2022 07:33:30 +0100 (CET) Date: Thu, 24 Feb 2022 07:33:30 +0100 From: Christoph Hellwig To: Heiko Carstens Cc: Christoph Hellwig , Baoquan He , linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, cl@linux.com, 42.hyeyoo@gmail.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, vbabka@suse.cz, David.Laight@aculab.com, david@redhat.com, herbert@gondor.apana.org.au, davem@davemloft.net, linux-crypto@vger.kernel.org, steffen.klassert@secunet.com, netdev@vger.kernel.org, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, linux-s390@vger.kernel.org, michael@walle.cc, linux-i2c@vger.kernel.org, wsa@kernel.org, Halil Pasic , Vineeth Vijayan Subject: Re: [PATCH 00/22] Don't use kmalloc() with GFP_DMA Message-ID: <20220224063330.GB20383@lst.de> References: <20220219005221.634-1-bhe@redhat.com> <20220222084422.GA6139@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Wed, Feb 23, 2022 at 08:18:08PM +0100, Heiko Carstens wrote: > > The long term goal is to remove ZONE_DMA entirely at least for > > architectures that only use the small 16MB ISA-style one. It can > > then be replaced with for example a CMA area and fall into a movable > > zone. I'd have to prototype this first and see how it applies to the > > s390 case. It might not be worth it and maybe we should replace > > ZONE_DMA and ZONE_DMA32 with a ZONE_LIMITED for those use cases as > > the amount covered tends to not be totally out of line for what we > > built the zone infrastructure. > > So probably I'm missing something; but for small systems where we > would only have ZONE_DMA, how would a CMA area within this zone > improve things? It would not, but more importantly we would not need it at all. The thinking here is really about the nasty 16MB ISA-style zone DMA. a 31-bit something rather different.