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=-5.5 required=3.0 tests=BAYES_00, 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 0DC3FC433DF for ; Wed, 22 Jul 2020 14:29:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DD59120729 for ; Wed, 22 Jul 2020 14:29:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732587AbgGVO3s (ORCPT ); Wed, 22 Jul 2020 10:29:48 -0400 Received: from verein.lst.de ([213.95.11.211]:56551 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732576AbgGVO3r (ORCPT ); Wed, 22 Jul 2020 10:29:47 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id B599868B05; Wed, 22 Jul 2020 16:29:43 +0200 (CEST) Date: Wed, 22 Jul 2020 16:29:43 +0200 From: Christoph Hellwig To: Barry Song Cc: hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com, will@kernel.org, ganapatrao.kulkarni@cavium.com, catalin.marinas@arm.com, iommu@lists.linux-foundation.org, linuxarm@huawei.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Jonathan Cameron , Nicolas Saenz Julienne , Steve Capper , Andrew Morton , Mike Rapoport Subject: Re: [PATCH v3 1/2] dma-direct: provide the ability to reserve per-numa CMA Message-ID: <20200722142943.GB17658@lst.de> References: <20200628111251.19108-1-song.bao.hua@hisilicon.com> <20200628111251.19108-2-song.bao.hua@hisilicon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200628111251.19108-2-song.bao.hua@hisilicon.com> 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, Jun 28, 2020 at 11:12:50PM +1200, Barry Song wrote: > struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) > { > size_t count = size >> PAGE_SHIFT; > struct page *page = NULL; > struct cma *cma = NULL; > + int nid = dev ? dev_to_node(dev) : NUMA_NO_NODE; > + bool alloc_from_pernuma = false; > + > + if ((count <= 1) && !(dev && dev->cma_area)) > + return NULL; > > if (dev && dev->cma_area) > cma = dev->cma_area; > - else if (count > 1) > + else if ((nid != NUMA_NO_NODE) && dma_contiguous_pernuma_area[nid] > + && !(gfp & (GFP_DMA | GFP_DMA32))) { > + cma = dma_contiguous_pernuma_area[nid]; > + alloc_from_pernuma = true; > + } else { > cma = dma_contiguous_default_area; > + } I find the function rather confusing now. What about something like (this relies on the fact that dev should never be NULL in the DMA API) struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) { size_t cma_align = min_t(size_t, get_order(size), CONFIG_CMA_ALIGNMENT); size_t count = size >> PAGE_SHIFT; if (gfpflags_allow_blocking(gfp)) return NULL; gfp &= __GFP_NOWARN; if (dev->cma_area) return cma_alloc(dev->cma_area, count, cma_align, gfp); if (count <= 1) return NULL; if (IS_ENABLED(CONFIG_PERNODE_CMA) && !(gfp & (GFP_DMA | GFP_DMA32)) { int nid = dev_to_node(dev); struct cma *cma = dma_contiguous_pernuma_area[nid]; struct page *page; if (cma) { page = cma_alloc(cma, count, cma_align, gfp); if (page) return page; } } return cma_alloc(dma_contiguous_default_area, count, cma_align, gfp); } > + /* > + * otherwise, page is from either per-numa cma or default cma > + */ > + int nid = page_to_nid(page); > + > + if (nid != NUMA_NO_NODE) { > + if (cma_release(dma_contiguous_pernuma_area[nid], page, > + PAGE_ALIGN(size) >> PAGE_SHIFT)) > + return; > + } > + > + if (cma_release(dma_contiguous_default_area, page, How can page_to_nid ever return NUMA_NO_NODE?