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[100.17.19.56]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8cb2b0e12eesm2128955585a.15.2026.02.19.09.10.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Feb 2026 09:10:42 -0800 (PST) Date: Thu, 19 Feb 2026 12:10:41 -0500 From: Eric Chanudet To: Christian =?utf-8?B?S8O2bmln?= Cc: Sumit Semwal , Benjamin Gaignard , Brian Starkey , John Stultz , "T.J. Mercier" , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, Maxime Ripard , Albert Esteve , linux-mm@kvack.org Subject: Re: [PATCH v2 3/3] dma-buf: heaps: cma: charge each cma heap's dmem Message-ID: References: <20260218-dmabuf-heap-cma-dmem-v2-0-b249886fb7b2@redhat.com> <20260218-dmabuf-heap-cma-dmem-v2-3-b249886fb7b2@redhat.com> <435330fd-ecdd-43c7-8527-f285c03c6421@amd.com> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <435330fd-ecdd-43c7-8527-f285c03c6421@amd.com> On Thu, Feb 19, 2026 at 08:17:28AM +0100, Christian König wrote: > > > 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 > > --- > > 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 > > #include > > #include > > +#include > > > > #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. > Agreed, while read-only it is easily missed without at least a comment. Alternatively, should that value be captured in the init callback to guaranty it is set once and make this requirement clearer? Thanks, > 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); > > > > > -- Eric Chanudet