diff mbox

[RFC,2/4] ARM: dma-mapping: IOMMU allocates pages from pool with GFP_ATOMIC

Message ID 1345630830-9586-3-git-send-email-hdoyu@nvidia.com
State New
Headers show

Commit Message

Hiroshi Doyu Aug. 22, 2012, 10:20 a.m. UTC
Makes use of the same atomic pool from DMA, and skips kernel page
mapping which can involves sleep'able operation at allocating a kernel
page table.

Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
---
 arch/arm/mm/dma-mapping.c |   22 ++++++++++++++++++----
 1 files changed, 18 insertions(+), 4 deletions(-)

Comments

Marek Szyprowski Aug. 22, 2012, 12:29 p.m. UTC | #1
Hello,

On Wednesday, August 22, 2012 12:20 PM Hiroshi Doyu wrote:

> Makes use of the same atomic pool from DMA, and skips kernel page
> mapping which can involves sleep'able operation at allocating a kernel
> page table.
> 
> Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
> ---
>  arch/arm/mm/dma-mapping.c |   22 ++++++++++++++++++----
>  1 files changed, 18 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index aec0c06..9260107 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -1028,7 +1028,6 @@ static struct page **__iommu_alloc_buffer(struct device *dev, size_t
> size,
>  	struct page **pages;
>  	int count = size >> PAGE_SHIFT;
>  	int array_size = count * sizeof(struct page *);
> -	int err;
> 
>  	if (array_size <= PAGE_SIZE)
>  		pages = kzalloc(array_size, gfp);
> @@ -1037,9 +1036,20 @@ static struct page **__iommu_alloc_buffer(struct device *dev, size_t
> size,
>  	if (!pages)
>  		return NULL;
> 
> -	err = __alloc_fill_pages(&pages, count, gfp);
> -	if (err)
> -		goto error
> +	if (gfp & GFP_ATOMIC) {
> +		struct page *page;
> +		int i;
> +		void *addr = __alloc_from_pool(size, &page);
> +		if (!addr)
> +			goto err_out;
> +
> +		for (i = 0; i < count; i++)
> +			pages[i] = page + i;
> +	} else {
> +		int err = __alloc_fill_pages(&pages, count, gfp);
> +		if (err)
> +			goto error;
> +	}
> 
>  	return pages;
>  error:
> @@ -1055,6 +1065,10 @@ static int __iommu_free_buffer(struct device *dev, struct page **pages,
> size_t s
>  	int count = size >> PAGE_SHIFT;
>  	int array_size = count * sizeof(struct page *);
>  	int i;
> +
> +	if (__free_from_pool(page_address(pages[0]), size))
> +		return 0;

You leak memory here. pages array should be also freed.

> +
>  	for (i = 0; i < count; i++)
>  		if (pages[i])
>  			__free_pages(pages[i], 0);
> --
> 1.7.5.4


Best regards
KyongHo Cho Aug. 22, 2012, 12:47 p.m. UTC | #2
Hi.

vzalloc() call in __iommu_alloc_buffer() also causes BUG() in atomic
context.


On Wed, Aug 22, 2012 at 7:20 PM, Hiroshi Doyu <hdoyu@nvidia.com> wrote:
> Makes use of the same atomic pool from DMA, and skips kernel page
> mapping which can involves sleep'able operation at allocating a kernel
> page table.
>
> Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com>
> ---
>  arch/arm/mm/dma-mapping.c |   22 ++++++++++++++++++----
>  1 files changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index aec0c06..9260107 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -1028,7 +1028,6 @@ static struct page **__iommu_alloc_buffer(struct
device *dev, size_t size,
>         struct page **pages;
>         int count = size >> PAGE_SHIFT;
>         int array_size = count * sizeof(struct page *);
> -       int err;
>
>         if (array_size <= PAGE_SIZE)
>                 pages = kzalloc(array_size, gfp);
> @@ -1037,9 +1036,20 @@ static struct page **__iommu_alloc_buffer(struct
device *dev, size_t size,
>         if (!pages)
>                 return NULL;
>
> -       err = __alloc_fill_pages(&pages, count, gfp);
> -       if (err)
> -               goto error
> +       if (gfp & GFP_ATOMIC) {
> +               struct page *page;
> +               int i;
> +               void *addr = __alloc_from_pool(size, &page);
> +               if (!addr)
> +                       goto err_out;
> +
> +               for (i = 0; i < count; i++)
> +                       pages[i] = page + i;
> +       } else {
> +               int err = __alloc_fill_pages(&pages, count, gfp);
> +               if (err)
> +                       goto error;
> +       }
>
>         return pages;
>  error:
> @@ -1055,6 +1065,10 @@ static int __iommu_free_buffer(struct device *dev,
struct page **pages, size_t s
>         int count = size >> PAGE_SHIFT;
>         int array_size = count * sizeof(struct page *);
>         int i;
> +
> +       if (__free_from_pool(page_address(pages[0]), size))
> +               return 0;
> +
>         for (i = 0; i < count; i++)
>                 if (pages[i])
>                         __free_pages(pages[i], 0);
> --
> 1.7.5.4
>
> --
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> see: http://www.linux-mm.org/ .
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diff mbox

Patch

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index aec0c06..9260107 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1028,7 +1028,6 @@  static struct page **__iommu_alloc_buffer(struct device *dev, size_t size,
 	struct page **pages;
 	int count = size >> PAGE_SHIFT;
 	int array_size = count * sizeof(struct page *);
-	int err;
 
 	if (array_size <= PAGE_SIZE)
 		pages = kzalloc(array_size, gfp);
@@ -1037,9 +1036,20 @@  static struct page **__iommu_alloc_buffer(struct device *dev, size_t size,
 	if (!pages)
 		return NULL;
 
-	err = __alloc_fill_pages(&pages, count, gfp);
-	if (err)
-		goto error
+	if (gfp & GFP_ATOMIC) {
+		struct page *page;
+		int i;
+		void *addr = __alloc_from_pool(size, &page);
+		if (!addr)
+			goto err_out;
+
+		for (i = 0; i < count; i++)
+			pages[i] = page + i;
+	} else {
+		int err = __alloc_fill_pages(&pages, count, gfp);
+		if (err)
+			goto error;
+	}
 
 	return pages;
 error:
@@ -1055,6 +1065,10 @@  static int __iommu_free_buffer(struct device *dev, struct page **pages, size_t s
 	int count = size >> PAGE_SHIFT;
 	int array_size = count * sizeof(struct page *);
 	int i;
+
+	if (__free_from_pool(page_address(pages[0]), size))
+		return 0;
+
 	for (i = 0; i < count; i++)
 		if (pages[i])
 			__free_pages(pages[i], 0);