Re: [Linaro-mm-sig] [RFC 2/4] ARM: dma-mapping: IOMMU allocates pages from pool with GFP_ATOMIC

Marek Szyprowski m.szyprowski@samsung.com wrote @ Wed, 22 Aug 2012 14:29:47 +0200:

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.

Right, I'll fix as below:

Modified arch/arm/mm/dma-mapping.c diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 47c4978..4656c0f 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -1121,11 +1121,12 @@ static int __iommu_free_buffer(struct device *dev, struct page **pages, size_t s int i;

if (__free_from_pool(page_address(pages[0]), size)) - return 0; + goto out;

for (i = 0; i < count; i++) if (pages[i]) __free_pages(pages[i], 0); +out: if (array_size <= PAGE_SIZE) kfree(pages); else