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 D4F0CC43219 for ; Sun, 13 Nov 2022 16:37:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235417AbiKMQgy (ORCPT ); Sun, 13 Nov 2022 11:36:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59554 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235446AbiKMQgb (ORCPT ); Sun, 13 Nov 2022 11:36:31 -0500 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D841311A25; Sun, 13 Nov 2022 08:36:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=bm9iJk+kVC/i+ZASfRIM102pV+AxG+Ji6MRA8D8G/hY=; b=D+OjBUBfCQQK7BJwONwAEfMW1V 8jRN6GgBR+VrL0tS3XZiRQ9Izl/KLvRdOZNqOKO2oIvVjbiEGO1c1mbTInhWzw5wANb8webd1H6p5 4/cHh9i8I5M7GvWwpaoJptq5AjmQRt8Uvmx0I5RXPXAGTwzpOau/gcI90NjYFBjagiMm2ZQ5k22MD 7he1X8jQVE3y/TPsjx6SSpehg1Wx7QAkYIJ9T/fxBFt3LhOvqAFBSPxj82bVviM8XSUfaM+n1JJeB F3Tse+cErMM0s3ZTGzoBDhUF3xq2vcmDdNxALOObw3iQy8FqQtrGg2svEfAxxHzAdX4NFzYvz8ba/ OKZme3wA==; Received: from 213-225-8-167.nat.highway.a1.net ([213.225.8.167] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1ouFxr-00CLdm-QM; Sun, 13 Nov 2022 16:36:12 +0000 From: Christoph Hellwig To: Dennis Dalessandro , Mauro Carvalho Chehab , Alexandra Winter , Wenjia Zhang , Marek Szyprowski , Jaroslav Kysela , Takashi Iwai , Russell King , Robin Murphy Cc: linux-arm-kernel@lists.infradead.org, linux-rdma@vger.kernel.org, iommu@lists.linux.dev, linux-media@vger.kernel.org, netdev@vger.kernel.org, linux-s390@vger.kernel.org, alsa-devel@alsa-project.org Subject: [PATCH 7/7] dma-mapping: reject __GFP_COMP in dma_alloc_attrs Date: Sun, 13 Nov 2022 17:35:35 +0100 Message-Id: <20221113163535.884299-8-hch@lst.de> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221113163535.884299-1-hch@lst.de> References: <20221113163535.884299-1-hch@lst.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org DMA allocations can never be turned back into a page pointer, so requesting compound pages doesn't make sense and it can't even be supported at all by various backends. Reject __GFP_COMP with a warning in dma_alloc_attrs, and stop clearing the flag in the arm dma ops and dma-iommu. Signed-off-by: Christoph Hellwig --- arch/arm/mm/dma-mapping.c | 17 ----------------- drivers/iommu/dma-iommu.c | 3 --- kernel/dma/mapping.c | 8 ++++++++ 3 files changed, 8 insertions(+), 20 deletions(-) diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index d7909091cf977..c135f6e37a00c 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -564,14 +564,6 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, if (mask < 0xffffffffULL) gfp |= GFP_DMA; - /* - * Following is a work-around (a.k.a. hack) to prevent pages - * with __GFP_COMP being passed to split_page() which cannot - * handle them. The real problem is that this flag probably - * should be 0 on ARM as it is not supported on this - * platform; see CONFIG_HUGETLBFS. - */ - gfp &= ~(__GFP_COMP); args.gfp = gfp; *handle = DMA_MAPPING_ERROR; @@ -1093,15 +1085,6 @@ static void *arm_iommu_alloc_attrs(struct device *dev, size_t size, return __iommu_alloc_simple(dev, size, gfp, handle, coherent_flag, attrs); - /* - * Following is a work-around (a.k.a. hack) to prevent pages - * with __GFP_COMP being passed to split_page() which cannot - * handle them. The real problem is that this flag probably - * should be 0 on ARM as it is not supported on this - * platform; see CONFIG_HUGETLBFS. - */ - gfp &= ~(__GFP_COMP); - pages = __iommu_alloc_buffer(dev, size, gfp, attrs, coherent_flag); if (!pages) return NULL; diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c index 9297b741f5e80..f798c44e09033 100644 --- a/drivers/iommu/dma-iommu.c +++ b/drivers/iommu/dma-iommu.c @@ -744,9 +744,6 @@ static struct page **__iommu_dma_alloc_pages(struct device *dev, /* IOMMU can map any pages, so himem can also be used here */ gfp |= __GFP_NOWARN | __GFP_HIGHMEM; - /* It makes no sense to muck about with huge pages */ - gfp &= ~__GFP_COMP; - while (count) { struct page *page = NULL; unsigned int order_size; diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 33437d6206445..c026a5a5e0466 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -498,6 +498,14 @@ void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle, WARN_ON_ONCE(!dev->coherent_dma_mask); + /* + * DMA allocations can never be turned back into a page pointer, so + * requesting compound pages doesn't make sense (and can't even be + * supported at all by various backends). + */ + if (WARN_ON_ONCE(flag & __GFP_COMP)) + return NULL; + if (dma_alloc_from_dev_coherent(dev, size, dma_handle, &cpu_addr)) return cpu_addr; -- 2.30.2