* [PATCH v2] dma-pool: don't allocate DMA32 pool if no 32-bit memory
[not found] <202601120747.TAMpIDnI-lkp@intel.com>
@ 2026-01-12 6:58 ` Vladimir Kondratiev
2026-01-12 12:43 ` Robin Murphy
0 siblings, 1 reply; 2+ messages in thread
From: Vladimir Kondratiev @ 2026-01-12 6:58 UTC (permalink / raw)
To: lkp, mick, Marek Szyprowski, Robin Murphy
Cc: iommu, linux-kernel, llvm, oe-kbuild-all, vladimir.kondratiev,
Vladimir.Kondratiev, akpm, alex, aou, hch, linux-mm, linux-riscv,
palmer, paul.walmsley
If system have no 32-bit memory, GFP_DMA32 pool allocation will
obviously fail, so skip it.
Changes in v2: use arch-independent "memblock_start_of_DRAM" to get
DRAM base address
Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev@mobileye.com>
---
kernel/dma/pool.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
index ee45dee33d49..ecd77a0272f2 100644
--- a/kernel/dma/pool.c
+++ b/kernel/dma/pool.c
@@ -209,7 +209,7 @@ static int __init dma_atomic_pool_init(void)
if (!atomic_pool_dma)
ret = -ENOMEM;
}
- if (IS_ENABLED(CONFIG_ZONE_DMA32)) {
+ if (IS_ENABLED(CONFIG_ZONE_DMA32) && memblock_start_of_DRAM() < BIT_ULL(32)) {
atomic_pool_dma32 = __dma_atomic_pool_init(atomic_pool_size,
GFP_KERNEL | GFP_DMA32);
if (!atomic_pool_dma32)
base-commit: 7d0a66e4bb9081d75c82ec4957c50034cb0ea449
--
2.43.0
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v2] dma-pool: don't allocate DMA32 pool if no 32-bit memory
2026-01-12 6:58 ` [PATCH v2] dma-pool: don't allocate DMA32 pool if no 32-bit memory Vladimir Kondratiev
@ 2026-01-12 12:43 ` Robin Murphy
0 siblings, 0 replies; 2+ messages in thread
From: Robin Murphy @ 2026-01-12 12:43 UTC (permalink / raw)
To: Vladimir Kondratiev, lkp, mick, Marek Szyprowski
Cc: iommu, linux-kernel, llvm, oe-kbuild-all, akpm, alex, aou, hch,
linux-mm, linux-riscv, palmer, paul.walmsley
On 2026-01-12 6:58 am, Vladimir Kondratiev wrote:
> If system have no 32-bit memory, GFP_DMA32 pool allocation will
> obviously fail, so skip it.
Note that the rest of the code doesn't quite work right if
CONFIG_ZONE_DMA32 is enabled but atomic_pool_dma32 is NULL - seems such
a setup wasn't really anticipated. Funnily enough, I also recently wrote
a patch series to improve this more generally, but hadn't got round to
writing a cover letter yet - lemme finish that up and post it...
Thanks,
Robin.
> Changes in v2: use arch-independent "memblock_start_of_DRAM" to get
> DRAM base address
>
> Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev@mobileye.com>
> ---
> kernel/dma/pool.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
> index ee45dee33d49..ecd77a0272f2 100644
> --- a/kernel/dma/pool.c
> +++ b/kernel/dma/pool.c
> @@ -209,7 +209,7 @@ static int __init dma_atomic_pool_init(void)
> if (!atomic_pool_dma)
> ret = -ENOMEM;
> }
> - if (IS_ENABLED(CONFIG_ZONE_DMA32)) {
> + if (IS_ENABLED(CONFIG_ZONE_DMA32) && memblock_start_of_DRAM() < BIT_ULL(32)) {
> atomic_pool_dma32 = __dma_atomic_pool_init(atomic_pool_size,
> GFP_KERNEL | GFP_DMA32);
> if (!atomic_pool_dma32)
>
> base-commit: 7d0a66e4bb9081d75c82ec4957c50034cb0ea449
^ permalink raw reply [flat|nested] 2+ messages in thread
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2026-01-12 6:58 ` [PATCH v2] dma-pool: don't allocate DMA32 pool if no 32-bit memory Vladimir Kondratiev
2026-01-12 12:43 ` Robin Murphy
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