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[PATCH v2 1/2] iommu/dma: Respect __GFP_DMA and __GFP_DMA32 in incoming GFP flags

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  [PATCH v2 1/2] iommu/dma: Respect __GFP_DMA and __GFP_DMA32 in incoming GFP flags Tomasz Figa <tfiga@chromium.org> - 2017-07-04 16:00 +0200
    [PATCH v2 2/2] iommu/dma: Use __GFP_NOWARN only for high-order allocations Tomasz Figa <tfiga@chromium.org> - 2017-07-04 16:00 +0200

#1680987 — [PATCH v2 1/2] iommu/dma: Respect __GFP_DMA and __GFP_DMA32 in incoming GFP flags

Current implementation of __iommu_dma_alloc_pages() keeps adding
__GFP_HIGHMEM to GFP flags regardless of whether other zone flags are
already included in the incoming flags. If __GFP_DMA or __GFP_DMA32 is
set at the same time as __GFP_HIGHMEM, the allocation fails due to
invalid zone flag combination.

Fix this by checking for __GFP_DMA and __GFP_DMA32 in incoming GFP flags
and adding __GFP_HIGHMEM only if they are not present.

Signed-off-by: Tomasz Figa <tfiga@chromium.org>
---
 drivers/iommu/dma-iommu.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

Changes from v1:
 - Update the comment as per Robin's suggestion.

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 9d1cebe7f6cb..bf23989b5158 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -445,8 +445,14 @@ static struct page **__iommu_dma_alloc_pages(unsigned int count,
 	if (!pages)
 		return NULL;
 
-	/* IOMMU can map any pages, so himem can also be used here */
-	gfp |= __GFP_NOWARN | __GFP_HIGHMEM;
+	/*
+	 * Unless we have some addressing limitation implied by GFP_DMA flags,
+	 * assume the IOMMU can map all of RAM and we can allocate anywhere.
+	 */
+	if (!(gfp & (__GFP_DMA | __GFP_DMA32)))
+		gfp |= __GFP_HIGHMEM;
+
+	gfp |= __GFP_NOWARN;
 
 	while (count) {
 		struct page *page = NULL;
-- 
2.13.2.725.g09c95d1e9-goog

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#1680992 — [PATCH v2 2/2] iommu/dma: Use __GFP_NOWARN only for high-order allocations

Memory allocation routines are expected to report allocation errors to
kernel log. However, current implementation of __iommu_dma_alloc_pages()
adds __GFP_NOWARN for all calls to alloc_pages(), which completely
disables any logging.

Fix it by adding __GFP_NOWARN only to high order allocation attempts,
which are not critical.

Signed-off-by: Tomasz Figa <tfiga@chromium.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
---
 drivers/iommu/dma-iommu.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

Changes from v1:
 - Fix typo in subject.
 - Add Robin's Reviewed-by.

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index bf23989b5158..6ed8c8f941d8 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -433,6 +433,7 @@ static struct page **__iommu_dma_alloc_pages(unsigned int count,
 {
 	struct page **pages;
 	unsigned int i = 0, array_size = count * sizeof(*pages);
+	const gfp_t high_order_gfp = __GFP_NOWARN | __GFP_NORETRY;
 
 	order_mask &= (2U << MAX_ORDER) - 1;
 	if (!order_mask)
@@ -452,8 +453,6 @@ static struct page **__iommu_dma_alloc_pages(unsigned int count,
 	if (!(gfp & (__GFP_DMA | __GFP_DMA32)))
 		gfp |= __GFP_HIGHMEM;
 
-	gfp |= __GFP_NOWARN;
-
 	while (count) {
 		struct page *page = NULL;
 		unsigned int order_size;
@@ -469,7 +468,7 @@ static struct page **__iommu_dma_alloc_pages(unsigned int count,
 
 			order_size = 1U << order;
 			page = alloc_pages((order_mask - order_size) ?
-					   gfp | __GFP_NORETRY : gfp, order);
+					   gfp | high_order_gfp : gfp, order);
 			if (!page)
 				continue;
 			if (!order)
-- 
2.13.2.725.g09c95d1e9-goog

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