On 30.03.2026 17:40, Maxime Ripard wrote:

Commit 3a236f6a5cf2 ("dma: contiguous: Turn heap registration logic around") didn't remove one last call to dma_heap_cma_register_heap() that it removed, thus breaking the build.

That last call is in dma_contiguous_reserve(), to handle the registration of the default CMA region heap instance.

The default CMA region instance is already somewhat handled by retrieving it through the dev_get_cma_area() call in the CMA heap driver. However, since commit 854acbe75ff4 ("dma-buf: heaps: Give default CMA heap a fixed name"), we will create two heap instances for the CMA default region.

The first one is always called "default_cma_region", and is the one handled by the call to dev_get_cma_area() mentioned earlier. The second one is the name it used to have prior to that last commit for backward compatibility.

In the case where the default CMA region is defined in the DT, then that region is registered through rmem_cma_setup() and that region is added to the list of CMA regions to create a CMA heap instance for.

In the case where the default CMA region is not defined in the DT though used to be the case covered by the now removed dma_heap_cma_register_heap() in dma_contiguous_reserve(). If we only remove the call to dma_heap_cma_register_heap(), then the legacy name of the CMA heap will not be registered anymore. We thus need to replace that call with a call to rmem_cma_insert_area() to make sure we queue this instance, if created, to create a heap instance.

Once that call to dma_heap_cma_register_heap() replaced, we can also remove the now unused function definition, its now empty header, and all includes of this header.

Fixes: 3a236f6a5cf2 ("dma: contiguous: Turn heap registration logic around") Reported-by: Mark Brown broonie@kernel.org Closes: https://lore.kernel.org/linux-next/acbjaDJ1a-YQC64d@sirena.co.uk/ Signed-off-by: Maxime Ripard mripard@kernel.org

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Changes in v2:

• Fix creation of the CMA heap instance with the legacy name when not declared in the DT.
• Link to v1: https://lore.kernel.org/r/20260330-dma-build-fix-v1-1-748b64f0d8af@kernel.or...

---

drivers/dma-buf/heaps/cma_heap.c | 1 - include/linux/dma-buf/heaps/cma.h | 16 ---------------- kernel/dma/contiguous.c | 14 +++++++++++--- 3 files changed, 11 insertions(+), 20 deletions(-)

diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c index 7216a14262b04bb6130ddf26b7d009f7d15b03fd..9a8b36bc929f6daa483a0139a2919d95127e0d23 100644 --- a/drivers/dma-buf/heaps/cma_heap.c +++ b/drivers/dma-buf/heaps/cma_heap.c @@ -12,11 +12,10 @@ #define pr_fmt(fmt) "cma_heap: " fmt #include <linux/cma.h> #include <linux/dma-buf.h> -#include <linux/dma-buf/heaps/cma.h> #include <linux/dma-heap.h> #include <linux/dma-map-ops.h> #include <linux/err.h> #include <linux/highmem.h> #include <linux/io.h> diff --git a/include/linux/dma-buf/heaps/cma.h b/include/linux/dma-buf/heaps/cma.h deleted file mode 100644 index e751479e21e703e24a5f799b4a7fc8bd0df3c1c4..0000000000000000000000000000000000000000 --- a/include/linux/dma-buf/heaps/cma.h +++ /dev/null @@ -1,16 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -#ifndef DMA_BUF_HEAP_CMA_H_ -#define DMA_BUF_HEAP_CMA_H_

-struct cma;

-#ifdef CONFIG_DMABUF_HEAPS_CMA -int dma_heap_cma_register_heap(struct cma *cma); -#else -static inline int dma_heap_cma_register_heap(struct cma *cma) -{

• return 0;

-} -#endif // CONFIG_DMABUF_HEAPS_CMA

-#endif // DMA_BUF_HEAP_CMA_H_ diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c index ad50512d71d3088a73e4b1ac02d6e6122374888e..d5d15983060c5c54744d6a63f2b591e1a3455b86 100644 --- a/kernel/dma/contiguous.c +++ b/kernel/dma/contiguous.c @@ -40,11 +40,10 @@ #include <asm/page.h> #include <linux/memblock.h> #include <linux/err.h> #include <linux/sizes.h> -#include <linux/dma-buf/heaps/cma.h> #include <linux/dma-map-ops.h> #include <linux/cma.h> #include <linux/nospec.h> #ifdef CONFIG_CMA_SIZE_MBYTES @@ -217,10 +216,19 @@ static void __init dma_numa_cma_reserve(void) static inline void __init dma_numa_cma_reserve(void) { } #endif +#ifdef CONFIG_OF_RESERVED_MEM +static int rmem_cma_insert_area(struct cma *cma); +#else +static inline int rmem_cma_insert_area(struct cma *cma) +{

• return 0;

+} +#endif

/**

• dma_contiguous_reserve() - reserve area(s) for contiguous memory handling
• @limit: End address of the reserved memory (optional, 0 for any).
• This function reserves memory from early allocator. It should be

@@ -271,13 +279,13 @@ void __init dma_contiguous_reserve(phys_addr_t limit) &dma_contiguous_default_area, fixed); if (ret) return;

• ret = dma_heap_cma_register_heap(dma_contiguous_default_area);
  

• ret = rmem_cma_insert_area(dma_contiguous_default_area);
  

  if (ret)

• 	pr_warn("Couldn't register default CMA heap.");
  

• 	pr_warn("Couldn't queue default CMA region for heap creation.");
  

  }

} void __weak dma_contiguous_early_fixup(phys_addr_t base, unsigned long size)

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Huh, this is still not the correct fix to restore the old behavior. When !CONFIG_OF_RESERVED_MEM the default cma area should be still registered as the default cma dma-buf heap.

Best regards