On Tue, Aug 27 2024, Marek Szyprowski wrote:

quoted

On 27.08.2024 06:52, Baruch Siach wrote:

quoted

Hi Marek,

Thanks for your report.

On Mon, Aug 26 2024, Marek Szyprowski wrote:

quoted

On 11.08.2024 09:09, Baruch Siach wrote:

quoted

From: Catalin Marinas <catalin.marinas@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@arm.com>
Co-developed-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Baruch Siach <baruch@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.

quoted

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;
  }