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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 CEDD2C3F2D1 for ; Thu, 5 Mar 2020 15:42:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 93C482073B for ; Thu, 5 Mar 2020 15:42:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726889AbgCEPmh (ORCPT ); Thu, 5 Mar 2020 10:42:37 -0500 Received: from verein.lst.de ([213.95.11.211]:60014 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725977AbgCEPmh (ORCPT ); Thu, 5 Mar 2020 10:42:37 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id BD43668B05; Thu, 5 Mar 2020 16:42:33 +0100 (CET) Date: Thu, 5 Mar 2020 16:42:33 +0100 From: Christoph Hellwig To: David Rientjes Cc: Christoph Hellwig , Tom Lendacky , "Singh, Brijesh" , "Grimm, Jon" , Joerg Roedel , baekhw@google.com, "linux-kernel@vger.kernel.org" , "iommu@lists.linux-foundation.org" Subject: Re: [rfc 2/6] dma-remap: add additional atomic pools to map to gfp mask Message-ID: <20200305154233.GA5332@lst.de> References: 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) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Mar 01, 2020 at 04:05:13PM -0800, David Rientjes wrote: > The single atomic pool is allocated from the lowest zone possible since > it is guaranteed to be applicable for any DMA allocation. > > Devices may allocate through the DMA API but not have a strict reliance > on GFP_DMA memory. Since the atomic pool will be used for all > non-blockable allocations, returning all memory from ZONE_DMA may > unnecessarily deplete the zone. > > Provision for multiple atomic pools that will map to the optimal gfp > mask of the device. These will be wired up in a subsequent patch. > > Signed-off-by: David Rientjes > --- > kernel/dma/remap.c | 75 +++++++++++++++++++++++++++------------------- > 1 file changed, 45 insertions(+), 30 deletions(-) > > diff --git a/kernel/dma/remap.c b/kernel/dma/remap.c > --- a/kernel/dma/remap.c > +++ b/kernel/dma/remap.c > @@ -100,6 +100,8 @@ void dma_common_free_remap(void *cpu_addr, size_t size) > > #ifdef CONFIG_DMA_DIRECT_REMAP > static struct gen_pool *atomic_pool __ro_after_init; > +static struct gen_pool *atomic_pool_dma32 __ro_after_init; > +static struct gen_pool *atomic_pool_normal __ro_after_init; Maybe rename atomic_pool as well as it really kinda looks like the default at the moment? > > #define DEFAULT_DMA_COHERENT_POOL_SIZE SZ_256K > static size_t atomic_pool_size __initdata = DEFAULT_DMA_COHERENT_POOL_SIZE; > @@ -111,66 +113,79 @@ static int __init early_coherent_pool(char *p) > } > early_param("coherent_pool", early_coherent_pool); > > -static gfp_t dma_atomic_pool_gfp(void) > +static int __init __dma_atomic_pool_init(struct gen_pool **pool, > + size_t pool_size, gfp_t gfp) > { Can this just return the pool and return NULL (or an ERR_PTR) on failure?