Re: [PATCH v2 3/3] dma-buf: heaps: cma: charge each cma heap's dmem

[Maxime Ripard <mripard@redhat.com>]

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Hi,

On Wed, Feb 18, 2026 at 12:14:12PM -0500, Eric Chanudet wrote:
> The cma dma-buf heaps let userspace allocate buffers in CMA regions
> without enforcing limits. Since each cma region registers in dmem,
> charge against it when allocating a buffer in a cma heap.
> 
> Signed-off-by: Eric Chanudet <echanude@redhat.com>
> ---
>  drivers/dma-buf/heaps/cma_heap.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
> index 49cc45fb42dd7200c3c14384bcfdbe85323454b1..bbd4f9495808da19256d97bd6a4dca3e1b0a30a0 100644
> --- a/drivers/dma-buf/heaps/cma_heap.c
> +++ b/drivers/dma-buf/heaps/cma_heap.c
> @@ -27,6 +27,7 @@
>  #include <linux/scatterlist.h>
>  #include <linux/slab.h>
>  #include <linux/vmalloc.h>
> +#include <linux/cgroup_dmem.h>
>  
>  #define DEFAULT_CMA_NAME "default_cma_region"
>  
> @@ -58,6 +59,7 @@ struct cma_heap_buffer {
>  	pgoff_t pagecount;
>  	int vmap_cnt;
>  	void *vaddr;
> +	struct dmem_cgroup_pool_state *pool;

I guess we should add an #if IS_ENABLED #endif guard for dmem?

>  };
>  
>  struct dma_heap_attachment {
> @@ -276,6 +278,7 @@ static void cma_heap_dma_buf_release(struct dma_buf *dmabuf)
>  	kfree(buffer->pages);
>  	/* release memory */
>  	cma_release(cma_heap->cma, buffer->cma_pages, buffer->pagecount);
> +	dmem_cgroup_uncharge(buffer->pool, buffer->len);
>  	kfree(buffer);
>  }
>  
> @@ -319,9 +322,17 @@ static struct dma_buf *cma_heap_allocate(struct dma_heap *heap,
>  	if (align > CONFIG_CMA_ALIGNMENT)
>  		align = CONFIG_CMA_ALIGNMENT;
>  
> +	if (mem_accounting) {
> +		ret = dmem_cgroup_try_charge(
> +			cma_get_dmem_cgroup_region(cma_heap->cma), size,
> +			&buffer->pool, NULL);

This alone doesn't call for a new version, but adhering to the kernel
coding style would look like this:

+		ret = dmem_cgroup_try_charge(cma_get_dmem_cgroup_region(cma_heap->cma),
+					     size, &buffer->pool, NULL);

It looks good to me otherwise,
Acked-by: Maxime Ripard <mripard@kernel.org>

Maxime

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