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

["Christian König" <christian.koenig@amd.com>]

On 2/18/26 18:14, 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;
>  };
>  
>  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) {

Since mem_accounting is a module parameter it is possible to make it changeable during runtime.

IIRC it currently is read only, but maybe add a one line comment that the cma heap now depends on that.

Apart from that the series looks totally sane to me.

Regards,
Christian.

> +		ret = dmem_cgroup_try_charge(
> +			cma_get_dmem_cgroup_region(cma_heap->cma), size,
> +			&buffer->pool, NULL);
> +		if (ret)
> +			goto free_buffer;
> +	}
> +
>  	cma_pages = cma_alloc(cma_heap->cma, pagecount, align, false);
>  	if (!cma_pages)
> -		goto free_buffer;
> +		goto uncharge_cgroup;
>  
>  	/* Clear the cma pages */
>  	if (PageHighMem(cma_pages)) {
> @@ -376,6 +387,8 @@ static struct dma_buf *cma_heap_allocate(struct dma_heap *heap,
>  	kfree(buffer->pages);
>  free_cma:
>  	cma_release(cma_heap->cma, cma_pages, pagecount);
> +uncharge_cgroup:
> +	dmem_cgroup_uncharge(buffer->pool, size);
>  free_buffer:
>  	kfree(buffer);
>  
>