Re: [PATCH v6 3/4] arm64: use both ZONE_DMA and ZONE_DMA32

From: Nicolas Saenz Julienne
Date: Mon Oct 21 2019 - 13:01:42 EST

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On Mon, 2019-10-21 at 10:46 -0400, Qian Cai wrote:
> > On Oct 21, 2019, at 10:34 AM, Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx
> > > wrote:
> >
> > On Mon, 2019-10-21 at 10:15 -0400, Qian Cai wrote:
> > > > On Sep 11, 2019, at 2:25 PM, Nicolas Saenz Julienne <
> > > > nsaenzjulienne@xxxxxxx>
> > > > wrote:
> > > >
> > > > So far all arm64 devices have supported 32 bit DMA masks for their
> > > > peripherals. This is not true anymore for the Raspberry Pi 4 as most of
> > > > it's peripherals can only address the first GB of memory on a total of
> > > > up to 4 GB.
> > > >
> > > > This goes against ZONE_DMA32's intent, as it's expected for ZONE_DMA32
> > > > to be addressable with a 32 bit mask. So it was decided to re-introduce
> > > > ZONE_DMA in arm64.
> > > >
> > > > ZONE_DMA will contain the lower 1G of memory, which is currently the
> > > > memory area addressable by any peripheral on an arm64 device.
> > > > ZONE_DMA32 will contain the rest of the 32 bit addressable memory.
> > > >
> > > > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx>
> > > > Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> > > >
> > > > ---
> > >
> > > With ZONE_DMA=y, this config will fail to reserve 512M CMA on a server,
> > >
> > > https://raw.githubusercontent.com/cailca/linux-mm/master/arm64.config
> > >
> > > CONFIG_DMA_CMA=y
> > > CONFIG_CMA_SIZE_MBYTES=64
> > > CONFIG_CMA_SIZE_SEL_MBYTES=y
> > > CONFIG_CMA_ALIGNMENT=8
> > > CONFIG_CMA=y
> > > CONFIG_CMA_DEBUGFS=y
> > > CONFIG_CMA_AREAS=7
> > >
> > > Is this expected?
> >
> > Not really, just tested cma=512M on a Raspberry Pi4, and it went well. The
> > only
> > thing on my build that differs from your config is CONFIG_CMA_DEBUGFS.
> >
> > Could you post more information on the device you're experiencing this on?
> > Also
> > some logs.
>
> With the above config, it does not even need "cma=512M" kernel cmdline.
>
> [ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x431f0af1]
> [ 0.000000] Linux version 5.4.0-rc4-next-20191021+ (clang version 8.0.1
> (Red Hat 8.0.1-1.module+el8.1.0+3866+6be7f4d8)) #1 SMP Mon Oct 21 10:03:03 EDT
> 2019
> [ 0.000000] Setting debug_guardpage_minorder to 1
> [ 0.000000] efi: Getting EFI parameters from FDT:
> [ 0.000000] efi: EFI v2.70 by American Megatrends
> [ 0.000000] efi: ESRT=0xf935ed98 SMBIOS=0xfcc90000 SMBIOS
> 3.0=0xfcc80000 ACPI 2.0=0xfac80000 MEMRESERVE=0xfacd1018
> [ 0.000000] esrt: Reserving ESRT space from 0x00000000f935ed98 to
> 0x00000000f935edd0.
> [ 0.000000] crashkernel reserved: 0x00000097db400000 - 0x00000097fb400000
> (512 MB)
> [ 0.000000] cma: Reserved 512 MiB at 0x00000000a0000000
>
> With ZONE_DMA=y, it will say,
>
> cma: Failed to reserve 512 MiB
>
> The machine is a ThunderX2 server.
>
>
https://buy.hpe.com/us/en/servers/apollo-systems/apollo-70-system/apollo-70-system/hpe-apollo-70-system/p/1010742472
>
> # lscpu
> Architecture: aarch64
> Byte Order: Little Endian
> CPU(s): 256
> On-line CPU(s) list: 0-255
> Thread(s) per core: 4
> Core(s) per socket: 32
> Socket(s): 2
> NUMA node(s): 2
> Vendor ID: Cavium
> Model: 1
> Model name: ThunderX2 99xx
> Stepping: 0x1
> BogoMIPS: 400.00
> L1d cache: 32K
> L1i cache: 32K
> L2 cache: 256K
> L3 cache: 32768K
> NUMA node0 CPU(s): 0-127
> NUMA node1 CPU(s): 128-255
> Flags: fp asimd aes pmull sha1 sha2 crc32 atomics cpuid asimdrdm

Hi Qian,
I happen to have access to a very similar machine:

thunderx25:~ # lscpu
Architecture: aarch64
Byte Order: Little Endian
CPU(s): 224
On-line CPU(s) list: 0-223
Thread(s) per core: 4
Core(s) per socket: 28
Socket(s): 2
NUMA node(s): 2
Vendor ID: Cavium
Model: 1
Model name: ThunderX2 99xx
Stepping: 0x1
CPU max MHz: 2500.0000
CPU min MHz: 1000.0000
BogoMIPS: 400.00
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 32768K
NUMA node0 CPU(s): 0-111
NUMA node1 CPU(s): 112-223
Flags: fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics cpuid
asimdrdm

I tested a kernel with your configuration plus CONFIG_ZONE_DMA=y yet I'm unable
to reproduce the error. The CMA allocation is successful.

[ 0.000000][ T0] Booting Linux on physical CPU 0x0000000000 [0x431f0af1]
[ 0.000000][ T0] Linux version 5.4.0-rc4-next-20191021 (nico@linux-9qgx) (gcc version 9.2.1 20190903 [gcc-9-branch revision 275330] (SUSE Linux)) #60 SMP Mon Oct 21 18:48:51 CEST 2019
[ 0.000000][ T0] printk: debug: ignoring loglevel setting.
[ 0.000000][ T0] efi: Getting EFI parameters from FDT:
[ 0.000000][ T0] efi: EFI v2.70 by American Megatrends
[ 0.000000][ T0] efi: ESRT=0xf10b4198 SMBIOS=0xfcc90000 SMBIOS 3.0=0xfcc80000 ACPI 2.0=0xf9670000 MEMRESERVE=0xf1117018
[ 0.000000][ T0] esrt: Reserving ESRT space from 0x00000000f10b4198 to 0x00000000f10b41d0.
[ 0.000000][ T0] cma: Reserved 512 MiB at 0x00000000a0000000
[ 0.000000][ T0] ACPI: Early table checksum verification disabled
[ 0.000000][ T0] ACPI: RSDP 0x00000000F9670000 000024 (v02 HPE )
[ 0.000000][ T0] ACPI: XSDT 0x00000000F9670028 0000DC (v01 HPE ServerCL 01072009 AMI 00010013)
[ 0.000000][ T0] ACPI: FACP 0x00000000F9670108 000114 (v06 HPE ServerCL 01072009 AMI 00010013)
[ 0.000000][ T0] ACPI: DSDT 0x00000000F9670220 000714 (v02 HPE ServerCL 20150406 INTL 20170831)
[ 0.000000][ T0] ACPI: FIDT 0x00000000F9670938 00009C (v01 HPE ServerCL 01072009 AMI 00010013)
[ 0.000000][ T0] ACPI: DBG2 0x00000000F96709D8 000062 (v00 HPE ServerCL 00000000 INTL 20170831)
[ 0.000000][ T0] ACPI: SPMI 0x00000000F9670A40 000041 (v05 HPE ServerCL 00000000 AMI. 00000000)
[ 0.000000][ T0] ACPI: PCCT 0x00000000F9670A88 000FB0 (v01 HPE ServerCL 00000001 INTL 20170831)
[ 0.000000][ T0] ACPI: SLIT 0x00000000F9671A38 000030 (v01 HPE ServerCL 00000001 INTL 20170831)
[ 0.000000][ T0] ACPI: SPMI 0x00000000F9671A68 000041 (v04 HPE ServerCL 00000001 INTL 20170831)
[ 0.000000][ T0] ACPI: SSDT 0x00000000F9671AB0 004217 (v02 HPE N0BXPCI 20150406 INTL 20170831)
[ 0.000000][ T0] ACPI: SSDT 0x00000000F9675CC8 019654 (v02 HPE ServerCL 20150406 INTL 20170831)
[ 0.000000][ T0] ACPI: SSDT 0x00000000F968F320 0041CB (v02 HPE N1BXPCI 20150406 INTL 20170831)
[ 0.000000][ T0] ACPI: SSDT 0x00000000F96934F0 01980C (v02 HPE ServerCL 20150406 INTL 20170831)
[ 0.000000][ T0] ACPI: BERT 0x00000000F96ACD00 000030 (v01 HPE ServerCL 20150406 CAVM 00000099)
[ 0.000000][ T0] ACPI: GTDT 0x00000000F96ACD30 00007C (v02 HPE ServerCL 20150406 CAVM 00000099)
[ 0.000000][ T0] ACPI: HEST 0x00000000F96ACDB0 000308 (v01 HPE ServerCL 20150406 CAVM 00000099)
[ 0.000000][ T0] ACPI: APIC 0x00000000F96AD0B8 00468C (v04 HPE ServerCL 20150406 CAVM 00000099)
[ 0.000000][ T0] ACPI: MCFG 0x00000000F96B1748 00003C (v01 HPE ServerCL 20150406 CAVM 00000099)
[ 0.000000][ T0] ACPI: NFIT 0x00000000F96B1788 000028 (v01 HPE ServerCL 20150406 CAVM 00000099)
[ 0.000000][ T0] ACPI: PPTT 0x00000000F96B17B0 0018B4 (v01 HPE ServerCL 20150406 CAVM 00000099)
[ 0.000000][ T0] ACPI: SRAT 0x00000000F96B3068 0010A8 (v03 HPE ServerCL 20150406 CAVM 00000099)
[ 0.000000][ T0] ACPI: IORT 0x00000000F96B4110 000688 (v00 HPE ServerCL 20150406 CAVM 00000099)
[ 0.000000][ T0] ACPI: BGRT 0x00000000F96B4798 000038 (v01 HPE ServerCL 01072009 AMI 00010013)
[ 0.000000][ T0] ACPI: SPCR 0x00000000F96B47D0 000050 (v02 HPE ServerCL 01072009 AMI. 0005000D)
[ 0.000000][ T0] ACPI: WSMT 0x00000000F96B4820 000028 (v01 HPE ServerCL 01072009 AMI 00010013)
[ 0.000000][ T0] ACPI: SPCR: Unexpected SPCR Access Width. Defaulting to byte size
[ 0.000000][ T0] ACPI: SPCR: console: pl011,mmio,0x402020000,115200
[ 0.000000][ T0] ACPI: SRAT: Node 0 PXM 0 [mem 0x80000000-0xfeffffff]
[ 0.000000][ T0] ACPI: SRAT: Node 0 PXM 0 [mem 0x880000000-0xfffffffff]
[ 0.000000][ T0] ACPI: SRAT: Node 0 PXM 0 [mem 0x8800000000-0x89fcffffff]
[ 0.000000][ T0] ACPI: SRAT: Node 1 PXM 1 [mem 0x89fd000000-0x93fcffffff]
[ 0.000000][ T0] NUMA: NODE_DATA [mem 0x89fcff5bc0-0x89fcffffff]
[ 0.000000][ T0] NUMA: NODE_DATA [mem 0x93fc5b5bc0-0x93fc5bffff]
[ 0.000000][ T0] Zone ranges:
[ 0.000000][ T0] DMA [mem 0x00000000802f0000-0x00000000bfffffff]
[ 0.000000][ T0] DMA32 [mem 0x00000000c0000000-0x00000000ffffffff]
[ 0.000000][ T0] Normal [mem 0x0000000100000000-0x00000093fcffffff]
[ 0.000000][ T0] Movable zone start for each node
[ 0.000000][ T0] Early memory node ranges
[ 0.000000][ T0] node 0: [mem 0x00000000802f0000-0x000000008030ffff]
[ 0.000000][ T0] node 0: [mem 0x0000000080310000-0x00000000bfffffff]
[ 0.000000][ T0] node 0: [mem 0x00000000c0000000-0x00000000c0cbffff]
[ 0.000000][ T0] node 0: [mem 0x00000000c0cc0000-0x00000000f104ffff]
[ 0.000000][ T0] node 0: [mem 0x00000000f1050000-0x00000000f10affff]
[ 0.000000][ T0] node 0: [mem 0x00000000f10b0000-0x00000000f96fffff]
[ 0.000000][ T0] node 0: [mem 0x00000000f9700000-0x00000000f98affff]
[ 0.000000][ T0] node 0: [mem 0x00000000f98b0000-0x00000000fa92ffff]
[ 0.000000][ T0] node 0: [mem 0x00000000fa930000-0x00000000faa6ffff]
[ 0.000000][ T0] node 0: [mem 0x00000000faa70000-0x00000000fabbffff]
[ 0.000000][ T0] node 0: [mem 0x00000000fabc0000-0x00000000fabdffff]
[ 0.000000][ T0] node 0: [mem 0x00000000fabe0000-0x00000000fadeffff]
[ 0.000000][ T0] node 0: [mem 0x00000000fadf0000-0x00000000fae4ffff]
[ 0.000000][ T0] node 0: [mem 0x00000000fae50000-0x00000000fc8cffff]
[ 0.000000][ T0] node 0: [mem 0x00000000fc8d0000-0x00000000fc8dffff]
[ 0.000000][ T0] node 0: [mem 0x00000000fc8e0000-0x00000000fca9ffff]
[ 0.000000][ T0] node 0: [mem 0x00000000fcaa0000-0x00000000fcaaffff]
[ 0.000000][ T0] node 0: [mem 0x00000000fcab0000-0x00000000fcb3ffff]
[ 0.000000][ T0] node 0: [mem 0x00000000fcb40000-0x00000000fd1effff]
[ 0.000000][ T0] node 0: [mem 0x00000000fd1f0000-0x00000000feceffff]
[ 0.000000][ T0] node 0: [mem 0x00000000fecf0000-0x00000000fed1ffff]
[ 0.000000][ T0] node 0: [mem 0x00000000fed20000-0x00000000fed2ffff]
[ 0.000000][ T0] node 0: [mem 0x00000000fed30000-0x00000000feddffff]
[ 0.000000][ T0] node 0: [mem 0x00000000fede0000-0x00000000feffffff]
[ 0.000000][ T0] node 0: [mem 0x0000000880000000-0x0000000fffffffff]
[ 0.000000][ T0] node 0: [mem 0x0000008800000000-0x00000089fcffffff]
[ 0.000000][ T0] node 1: [mem 0x00000089fd000000-0x00000093fcffffff]
[ 0.000000][ T0] Zeroed struct page in unavailable ranges: 440 pages
[ 0.000000][ T0] Initmem setup node 0 [mem 0x00000000802f0000-0x00000089fcffffff]
[ 0.000000][ T0] On node 0 totalpages: 654289
[ 0.000000][ T0] DMA zone: 16 pages used for memmap
[ 0.000000][ T0] DMA zone: 0 pages reserved
[ 0.000000][ T0] DMA zone: 16337 pages, LIFO batch:3
[ 0.000000][ T0] DMA32 zone: 16 pages used for memmap
[ 0.000000][ T0] DMA32 zone: 16128 pages, LIFO batch:3
[ 0.000000][ T0] Normal zone: 608 pages used for memmap
[ 0.000000][ T0] Normal zone: 621824 pages, LIFO batch:3
[ 0.000000][ T0] Initmem setup node 1 [mem 0x00000089fd000000-0x00000093fcffffff]
[ 0.000000][ T0] On node 1 totalpages: 655360
[ 0.000000][ T0] Normal zone: 640 pages used for memmap
[ 0.000000][ T0] Normal zone: 655360 pages, LIFO batch:3

Could you enable CMA debugging to see if anything interesting comes out of it.

Regards,
Nicolas

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Next message: Doug Anderson: "Re: [PATCH v2] kdb: Avoid array subscript warnings on non-SMP builds"
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In reply to: Qian Cai: "Re: [PATCH v6 3/4] arm64: use both ZONE_DMA and ZONE_DMA32"
Next in thread: Qian Cai: "Re: [PATCH v6 3/4] arm64: use both ZONE_DMA and ZONE_DMA32"
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