[PATCH v6 RESED 1/2] dma: replace zone_dma_bits by zone_dma_limit

[Marek Szyprowski]

On 27.08.2024 09:03, Baruch Siach wrote:
> On Tue, Aug 27 2024, Marek Szyprowski wrote:
>> On 27.08.2024 06:52, Baruch Siach wrote:
>>> Hi Marek,
>>>
>>> Thanks for your report.
>>>
>>> On Mon, Aug 26 2024, Marek Szyprowski wrote:
>>>> On 11.08.2024 09:09, Baruch Siach wrote:
>>>>> From: Catalin Marinas <catalin.marinas at arm.com>
>>>>>
>>>>> Hardware DMA limit might not be power of 2. When RAM range starts above
>>>>> 0, say 4GB, DMA limit of 30 bits should end at 5GB. A single high bit
>>>>> can not encode this limit.
>>>>>
>>>>> Use plain address for DMA zone limit.
>>>>>
>>>>> Since DMA zone can now potentially span beyond 4GB physical limit of
>>>>> DMA32, make sure to use DMA zone for GFP_DMA32 allocations in that case.
>>>>>
>>>>> Signed-off-by: Catalin Marinas <catalin.marinas at arm.com>
>>>>> Co-developed-by: Baruch Siach <baruch at tkos.co.il>
>>>>> Signed-off-by: Baruch Siach <baruch at tkos.co.il>
>>>>> ---
>>>> This patch landed recently in linux-next as commit ba0fb44aed47
>>>> ("dma-mapping: replace zone_dma_bits by zone_dma_limit"). During my
>>>> tests I found that it introduces the following warning on ARM64/Rockchip
>>>> based Odroid M1 board (arch/arm64/boot/dts/rockchip/rk3568-odroid-m1.dts):
>>> Does this warning go away if you revert both 3be9b846896d and ba0fb44aed47?
>> Yes, linux-next with above mentioned commits reverted works fine.
>>
>>
>>> Upstream rockchip DTs have no dma-ranges property. Is that the case for
>>> your platform as well?
>>>
>>> Can you share kernel report of DMA zones and swiotlb? On my platform I get:
>>>
>>> [    0.000000] Zone ranges:
>>> [    0.000000]   DMA      [mem 0x0000000800000000-0x000000083fffffff]
>>> [    0.000000]   DMA32    empty
>>> [    0.000000]   Normal   [mem 0x0000000840000000-0x0000000fffffffff]
>>> ...
>>> [    0.000000] software IO TLB: area num 8.
>>> [    0.000000] software IO TLB: mapped [mem 0x000000083be38000-0x000000083fe38000] (64MB)
>>>
>>> What do you get at your end?
>> On ba0fb44aed47 I got:
>>
>> [    0.000000] NUMA: No NUMA configuration found
>> [    0.000000] NUMA: Faking a node at [mem
>> 0x0000000000200000-0x00000001ffffffff]
>> [    0.000000] NUMA: NODE_DATA [mem 0x1ff7a0600-0x1ff7a2fff]
>> [    0.000000] Zone ranges:
>> [    0.000000]   DMA      [mem 0x0000000000200000-0x00000001ffffffff]
>> [    0.000000]   DMA32    empty
>> [    0.000000]   Normal   empty
>> [    0.000000] Movable zone start for each node
>> [    0.000000] Early memory node ranges
>> [    0.000000]   node   0: [mem 0x0000000000200000-0x00000000083fffff]
>> [    0.000000]   node   0: [mem 0x0000000009400000-0x00000000efffffff]
>> [    0.000000]   node   0: [mem 0x00000001f0000000-0x00000001ffffffff]
>> [    0.000000] Initmem setup node 0 [mem
>> 0x0000000000200000-0x00000001ffffffff]
>> [    0.000000] On node 0, zone DMA: 512 pages in unavailable ranges
>> [    0.000000] On node 0, zone DMA: 4096 pages in unavailable ranges
>> [    0.000000] cma: Reserved 96 MiB at 0x00000001f0000000 on node -1
>>
>> ...
>>
>> [    0.000000] software IO TLB: SWIOTLB bounce buffer size adjusted to 3MB
>> [    0.000000] software IO TLB: area num 4.
>> [    0.000000] software IO TLB: mapped [mem
>> 0x00000001fac00000-0x00000001fb000000] (4MB)
>>
>> On the fa3c109a6d30 (parent commit of the $subject) I got:
>>
>> [    0.000000] NUMA: No NUMA configuration found
>> [    0.000000] NUMA: Faking a node at [mem
>> 0x0000000000200000-0x00000001ffffffff]
>> [    0.000000] NUMA: NODE_DATA [mem 0x1ff7a0600-0x1ff7a2fff]
>> [    0.000000] Zone ranges:
>> [    0.000000]   DMA      [mem 0x0000000000200000-0x00000000ffffffff]
>> [    0.000000]   DMA32    empty
>> [    0.000000]   Normal   [mem 0x0000000100000000-0x00000001ffffffff]
>> [    0.000000] Movable zone start for each node
>> [    0.000000] Early memory node ranges
>> [    0.000000]   node   0: [mem 0x0000000000200000-0x00000000083fffff]
>> [    0.000000]   node   0: [mem 0x0000000009400000-0x00000000efffffff]
>> [    0.000000]   node   0: [mem 0x00000001f0000000-0x00000001ffffffff]
>> [    0.000000] Initmem setup node 0 [mem
>> 0x0000000000200000-0x00000001ffffffff]
>> [    0.000000] On node 0, zone DMA: 512 pages in unavailable ranges
>> [    0.000000] On node 0, zone DMA: 4096 pages in unavailable ranges
>> [    0.000000] cma: Reserved 96 MiB at 0x00000000ea000000 on node -1
>>
>> ...
>>
>> [    0.000000] software IO TLB: area num 4.
>> [    0.000000] software IO TLB: mapped [mem
>> 0x00000000e6000000-0x00000000ea000000] (64MB)
>>
>> It looks that for some reasons $subject patch changes the default zone
>> and swiotlb configuration.
> Does this fix the issue?
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index bfb10969cbf0..7fcd0aaa9bb6 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -116,6 +116,9 @@ static void __init arch_reserve_crashkernel(void)
>   
>   static phys_addr_t __init max_zone_phys(phys_addr_t zone_limit)
>   {
> +	if (memblock_start_of_DRAM() < U32_MAX)
> +		zone_limit = min(zone_limit, U32_MAX);
> +
>   	return min(zone_limit, memblock_end_of_DRAM() - 1) + 1;
>   }
>   

Yes, this fixes my issue. Thanks!

Fell free to add:

Reported-by: Marek Szyprowski <m.szyprowski at samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski at samsung.com>

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland