From: Christoph Hellwig <hch@lst.de>
To: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Alexandra Winter <wintera@linux.ibm.com>,
Wenjia Zhang <wenjia@linux.ibm.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>,
Russell King <linux@armlinux.org.uk>,
Robin Murphy <robin.murphy@arm.com>
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 [thread overview]
Message-ID: <20221113163535.884299-8-hch@lst.de> (raw)
In-Reply-To: <20221113163535.884299-1-hch@lst.de>
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 <hch@lst.de>
---
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
next prev parent reply other threads:[~2022-11-13 16:37 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-13 16:35 stop drivers from passing GFP_COMP to dma_alloc_coherent Christoph Hellwig
2022-11-13 16:35 ` [PATCH 1/7] media: videobuf-dma-contig: use dma_mmap_coherent Christoph Hellwig
2022-11-24 14:10 ` Hans Verkuil
2022-11-29 14:00 ` Christoph Hellwig
2022-11-13 16:35 ` [PATCH 2/7] RDMA/hfi1: don't pass bogus GFP_ flags to dma_alloc_coherent Christoph Hellwig
2022-11-15 20:39 ` Jason Gunthorpe
2022-11-16 14:40 ` Dean Luick
2022-11-16 15:15 ` Robin Murphy
2022-11-16 15:45 ` Christoph Hellwig
2022-11-16 17:49 ` Dean Luick
2022-11-20 20:41 ` Dean Luick
2022-11-16 16:21 ` Dean Luick
2022-11-16 18:37 ` Robin Murphy
2022-11-13 16:35 ` [PATCH 3/7] RDMA/qib: " Christoph Hellwig
2022-11-15 20:40 ` Jason Gunthorpe
2022-11-13 16:35 ` [PATCH 4/7] cnic: " Christoph Hellwig
2022-11-13 16:35 ` [PATCH 5/7] s390/ism: " Christoph Hellwig
2022-11-16 12:39 ` Wenjia Zhang
2022-11-13 16:35 ` [PATCH 6/7] ALSA: memalloc: don't pass bogus GFP_ flags to dma_alloc_* Christoph Hellwig
2022-11-14 9:04 ` Takashi Iwai
2022-11-21 8:37 ` Christoph Hellwig
2022-11-13 16:35 ` Christoph Hellwig [this message]
2022-11-14 8:11 ` [PATCH 7/7] dma-mapping: reject __GFP_COMP in dma_alloc_attrs Leon Romanovsky
2022-11-16 6:11 ` Christoph Hellwig
2022-11-16 7:11 ` Leon Romanovsky
2022-11-14 12:16 ` Marek Szyprowski
2022-11-21 8:39 ` stop drivers from passing GFP_COMP to dma_alloc_coherent Christoph Hellwig
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