When debugging is disabled, kzalloc returns page-aligned
addresses:
Is it defined some where that regular kzalloc/kmalloc guaranties to
return a page-aligned address as you see in your testing ? if so the
debug mode should behave the same. Otherwise we can consider using any
flag allocation that can force that if such exists.
Let's get other people's input here.
My understanding is that the fact that k[mz]alloc() returns a
page-aligned buffer if the allocation size is > PAGE_SIZE / 2 is a
side effect of the implementation and not something callers of that
function should rely on. I think the only assumption k[mz]alloc()
callers should rely on is that the allocated memory respects
ARCH_KMALLOC_MINALIGN.
I agree. mlx4_alloc_priv_pages() is carefully designed to
correct the alignment of the buffer, so it already assumes
that it is not getting a page-aligned buffer.
The alignment isn't the problem here, though. It's that
the buffer contains a page-boundary. That is guaranteed
to be the case for HCAs that support more than 512
sges, so that will have to be addressed (at least in
mlx5).
rrr...
I think we should make the pages allocations dma coherent
in order to fix that...
Nice catch Chunk.
Does this untested patch help (if so, mlx5 will need an identical patch)?
--
diff --git a/drivers/infiniband/hw/mlx4/mlx4_ib.h
b/drivers/infiniband/hw/mlx4/mlx4_ib.h
index ba328177eae9..78e9b3addfea 100644
--- a/drivers/infiniband/hw/mlx4/mlx4_ib.h
+++ b/drivers/infiniband/hw/mlx4/mlx4_ib.h
@@ -139,7 +139,6 @@ struct mlx4_ib_mr {
u32 max_pages;
struct mlx4_mr mmr;
struct ib_umem *umem;
- void *pages_alloc;
};
struct mlx4_ib_mw {
diff --git a/drivers/infiniband/hw/mlx4/mr.c
b/drivers/infiniband/hw/mlx4/mr.c
index b04f6238e7e2..becb4a65c755 100644
--- a/drivers/infiniband/hw/mlx4/mr.c
+++ b/drivers/infiniband/hw/mlx4/mr.c
@@ -278,30 +278,13 @@ mlx4_alloc_priv_pages(struct ib_device *device,
int max_pages)
{
int size = max_pages * sizeof(u64);
- int add_size;
- int ret;
-
- add_size = max_t(int, MLX4_MR_PAGES_ALIGN -
ARCH_KMALLOC_MINALIGN, 0);
- mr->pages_alloc = kzalloc(size + add_size, GFP_KERNEL);
- if (!mr->pages_alloc)
+ mr->pages = dma_alloc_coherent(device->dma_device, size,
+ &mr->page_map, GFP_KERNEL);
+ if (!mr->pages)
return -ENOMEM;
- mr->pages = PTR_ALIGN(mr->pages_alloc, MLX4_MR_PAGES_ALIGN);
-
- mr->page_map = dma_map_single(device->dma_device, mr->pages,
- size, DMA_TO_DEVICE);
-
- if (dma_mapping_error(device->dma_device, mr->page_map)) {
- ret = -ENOMEM;
- goto err;
- }
-
return 0;
-err:
- kfree(mr->pages_alloc);
-
- return ret;
}
static void
@@ -311,9 +294,8 @@ mlx4_free_priv_pages(struct mlx4_ib_mr *mr)
struct ib_device *device = mr->ibmr.device;
int size = mr->max_pages * sizeof(u64);
- dma_unmap_single(device->dma_device, mr->page_map,
- size, DMA_TO_DEVICE);
- kfree(mr->pages_alloc);
+ dma_free_coherent(device->dma_device, size,
+ mr->pages, mr->page_map);
mr->pages = NULL;
}
}
@@ -532,19 +514,8 @@ int mlx4_ib_map_mr_sg(struct ib_mr *ibmr, struct
scatterlist *sg, int sg_nents,
unsigned int sg_offset)
{
struct mlx4_ib_mr *mr = to_mmr(ibmr);
- int rc;
mr->npages = 0;
- ib_dma_sync_single_for_cpu(ibmr->device, mr->page_map,
- sizeof(u64) * mr->max_pages,
- DMA_TO_DEVICE);
-
- rc = ib_sg_to_pages(ibmr, sg, sg_nents, sg_offset, mlx4_set_page);
-
- ib_dma_sync_single_for_device(ibmr->device, mr->page_map,
- sizeof(u64) * mr->max_pages,
- DMA_TO_DEVICE);
-
- return rc;
+ return ib_sg_to_pages(ibmr, sg, sg_nents, sg_offset, mlx4_set_page);
}
--
--
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