From patchwork Sun Nov 13 16:35:35 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 13041611 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8C780C4332F for ; Sun, 13 Nov 2022 16:37:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=84YQ9fKMSmXd1iaV7394g2kScUEse0xQSoJFe1c6OLA=; b=Ivc1pvLIQ2LkR0 9l/PfsAFAdzcdqgDYeZv20KiTQ6xyWdvDFWPbarYdCJoS2zEuN9eUPq5vA5E3OhB+uGSRYjR+iJIG uN6gREMD5FSSmHipIhVQ5mBihyTGW13nBFzYt1BWVJN3qUlNo0Hoes39qnz3F+b3QkqKMjdvE9M7X cznU6TqEpDFXPzVtCX00eyRiOTMPCaOsvso1gTg8/+bxD0OPTZHLHm+xlH6YRUhwSOhJWHMbPwXNK dEL1nTUL1oPvmhzgZuJwey9P3yAT9CPv6anV0nec3txCkRclcfurhDkbyVprQGfNa/BWoa4/WbcGD qEiLx2ZUNNWh36GsANEQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ouFyb-00CM92-RE; Sun, 13 Nov 2022 16:36:57 +0000 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 X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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 Acked-by: Marek Szyprowski --- 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;