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

From: Vova Sharaienko

Date: Tue Jun 23 2026 - 20:05:36 EST


We are proposing to 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.

This is currently marked as an RFC because we would like feedback on
a KiB unit change.

Signed-off-by: Vova Sharaienko <sharaienko@xxxxxxxxxx>
---
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 480dd1766ece..3ede8da395ce 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 %lu KiB\n",
+ &phys_addr, (unsigned long)(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 %lu KiB\n",
+ &rmem->base, (unsigned long)(rmem->size / SZ_1K));
return 0;
}

--
2.55.0.rc0.799.gd6f94ed593-goog