[PATCH v2] dma-coherent: use KiB in DMA allocation logs

[PATCH v2] dma-coherent: use KiB in DMA allocation logs

[Vova Sharaienko]

Update DMA reserved memory pool allocation log messages to display
sizes in KiB instead of MiB. Using MiB caused allocations less than
1 MiB to be logged as 0 MiB due to integer truncation. KiB provides
better precision for smaller memory regions specified in the Device Tree.

Signed-off-by: Vova Sharaienko <sharaienko@google.com>
---
v1: https://lore.kernel.org/all/20260624000516.597555-1-sharaienko@google.com/
Addressed feedback from v1: changed %ld to %llu for size in KiB
to avoid truncation for sizes (which can be 64-bit on a 32-bit kernel)
larger than 4 GiB.

 kernel/dma/coherent.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c
index bcdc0f76d2e8..67f9a88ec4fe 100644
--- a/kernel/dma/coherent.c
+++ b/kernel/dma/coherent.c
@@ -69,8 +69,8 @@ static struct dma_coherent_mem *dma_init_coherent_memory(phys_addr_t phys_addr,
 	kfree(dma_mem);
 out_unmap_membase:
 	memunmap(mem_base);
-	pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %zd MiB\n",
-		&phys_addr, size / SZ_1M);
+	pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %zu KiB\n",
+		&phys_addr, size / SZ_1K);
 	return ERR_PTR(-ENOMEM);
 }

@@ -384,8 +384,8 @@ static int __init rmem_dma_setup(unsigned long node, struct reserved_mem *rmem)
 	}
 #endif

-	pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
-		&rmem->base, (unsigned long)rmem->size / SZ_1M);
+	pr_info("Reserved memory: created DMA memory pool at %pa, size %llu KiB\n",
+		&rmem->base, (unsigned long long)(rmem->size / SZ_1K));
 	return 0;
 }

--
2.55.0.rc0.799.gd6f94ed593-goog

Re: [PATCH v2] dma-coherent: use KiB in DMA allocation logs

[Marek Szyprowski]

On 30.06.2026 00:37, Vova Sharaienko wrote:
> Update DMA reserved memory pool allocation log messages to display
> sizes in KiB instead of MiB. Using MiB caused allocations less than
> 1 MiB to be logged as 0 MiB due to integer truncation. KiB provides
> better precision for smaller memory regions specified in the Device Tree.
>
> Signed-off-by: Vova Sharaienko <sharaienko@google.com>


Applied to dma-mapping-for-next. Thanks!


> ---
> v1: https://lore.kernel.org/all/20260624000516.597555-1-sharaienko@google.com/
> Addressed feedback from v1: changed %ld to %llu for size in KiB
> to avoid truncation for sizes (which can be 64-bit on a 32-bit kernel)
> larger than 4 GiB.
>
>  kernel/dma/coherent.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c
> index bcdc0f76d2e8..67f9a88ec4fe 100644
> --- a/kernel/dma/coherent.c
> +++ b/kernel/dma/coherent.c
> @@ -69,8 +69,8 @@ static struct dma_coherent_mem *dma_init_coherent_memory(phys_addr_t phys_addr,
>  	kfree(dma_mem);
>  out_unmap_membase:
>  	memunmap(mem_base);
> -	pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %zd MiB\n",
> -		&phys_addr, size / SZ_1M);
> +	pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %zu KiB\n",
> +		&phys_addr, size / SZ_1K);
>  	return ERR_PTR(-ENOMEM);
>  }
>
> @@ -384,8 +384,8 @@ static int __init rmem_dma_setup(unsigned long node, struct reserved_mem *rmem)
>  	}
>  #endif
>
> -	pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
> -		&rmem->base, (unsigned long)rmem->size / SZ_1M);
> +	pr_info("Reserved memory: created DMA memory pool at %pa, size %llu KiB\n",
> +		&rmem->base, (unsigned long long)(rmem->size / SZ_1K));
>  	return 0;
>  }
>
> --
> 2.55.0.rc0.799.gd6f94ed593-goog
>
>
Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland