ARM_LPAE + VMSPLIT_2G cause swiotlb warning on Raspberry Pi 4

Tue May 16 13:46:01 PDT 2023

Hi,
today i wanted to test the new arm/multi_v7_lpae_defconfig on my 
Raspberry Pi 4 8GB with Linux 6.4-rc2, but it fails everytime to boot 
properly from SD card:

[    0.000000] Booting Linux on physical CPU 0x0
[    0.000000] Linux version 6.4.0-rc2 (stefanw at stefanw-SCHENKER) 
(arm-linux-gnueabihf-gcc (GCC) 11.3.1 20220604 [releases/gcc-11 revision 
591c0f4b92548e3ae2e8173f4f93984b1c7f62bb], GNU ld 
(Linaro_Binutils-2022.06) 2.37.20220122) #2 SMP Tue May 16 18:57:48 CEST 
2023
[    0.000000] CPU: ARMv7 Processor [410fd083] revision 3 (ARMv7), 
cr=30c5383d
[    0.000000] CPU: div instructions available: patching division code
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, PIPT instruction 
cache
[    0.000000] OF: fdt: Machine model: Raspberry Pi 4 Model B Rev 1.4
[    0.000000] random: crng init done
[    0.000000] Memory policy: Data cache writealloc
[    0.000000] efi: UEFI not found.
[    0.000000] Reserved memory: created CMA memory pool at 
0x0000000037000000, size 64 MiB
[    0.000000] OF: reserved mem: initialized node linux,cma, compatible 
id shared-dma-pool
[    0.000000] OF: reserved mem: 0x0000000037000000..0x000000003affffff 
(65536 KiB) map reusable linux,cma
[    0.000000] OF: reserved mem: 0x000000003ef625a0..0x000000003ef62681 
(0 KiB) nomap non-reusable nvram at 0
[    0.000000] Zone ranges:
[    0.000000]   DMA      [mem 0x0000000000000000-0x000000003fffefff]
[    0.000000]   Normal   [mem 0x000000003ffff000-0x000000006fffffff]
[    0.000000]   HighMem  [mem 0x0000000070000000-0x00000001ffffffff]
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000000000000-0x000000003b3fffff]
[    0.000000]   node   0: [mem 0x0000000040000000-0x00000000fbffffff]
[    0.000000]   node   0: [mem 0x0000000100000000-0x00000001ffffffff]
[    0.000000] Initmem setup node 0 [mem 
0x0000000000000000-0x00000001ffffffff]
[    0.000000] On node 0, zone Normal: 1024 pages in unavailable ranges
[    0.000000] percpu: Embedded 16 pages/cpu s35988 r8192 d21356 u65536
[    0.000000] Kernel command line:  dma.dmachans=0x37f5 
bcm2709.boardrev=0xd03114 bcm2709.serial=0x2e99bd7a 
bcm2709.uart_clock=48000000 bcm2709.disk_led_gpio=42 
bcm2709.disk_led_active_low=0 smsc95xx.macaddr=DC:A6:32:91:38:52 
vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000 
console=ttyS1,115200 console=tty1 root=PARTUUID=a5c5156c-02 
rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait 
plymouth.ignore-serial-consoles

...

[    1.422481] pcieport 0000:00:00.0: enabling device (0000 -> 0002)
[    1.422621] pcieport 0000:00:00.0: PME: Signaling with IRQ 35
[    1.434696] ------------[ cut here ]------------
[    1.434720] WARNING: CPU: 2 PID: 1 at kernel/dma/swiotlb.c:891 
swiotlb_map+0x328/0x330
[    1.434759] bcm2835-dma fe007000.dma: swiotlb addr 
0xffffffffffffffff+4096 overflow (mask ffffffff, bus limit ffffffff).
[    1.434790] Modules linked in:
[    1.434813] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 6.4.0-rc2 #2
[    1.434838] Hardware name: BCM2711
[    1.434862]  unwind_backtrace from show_stack+0x10/0x14
[    1.434902]  show_stack from dump_stack_lvl+0x40/0x4c
[    1.434938]  dump_stack_lvl from __warn+0x7c/0x124
[    1.434980]  __warn from warn_slowpath_fmt+0x118/0x174
[    1.435024]  warn_slowpath_fmt from swiotlb_map+0x328/0x330
[    1.435062]  swiotlb_map from dma_map_page_attrs+0x204/0x328
[    1.435100]  dma_map_page_attrs from bcm2835_dma_probe+0x1d8/0x41c
[    1.435141]  bcm2835_dma_probe from platform_probe+0x5c/0xbc
[    1.435174]  platform_probe from really_probe+0xc8/0x2dc
[    1.435214]  really_probe from __driver_probe_device+0x88/0x19c
[    1.435262]  __driver_probe_device from driver_probe_device+0x30/0x104
[    1.435310]  driver_probe_device from __driver_attach+0x90/0x174
[    1.435357]  __driver_attach from bus_for_each_dev+0x6c/0xb4
[    1.435402]  bus_for_each_dev from bus_add_driver+0xcc/0x1cc
[    1.435445]  bus_add_driver from driver_register+0x7c/0x118
[    1.435479]  driver_register from do_one_initcall+0x40/0x1e0
[    1.435509]  do_one_initcall from kernel_init_freeable+0x1b8/0x220
[    1.435549]  kernel_init_freeable from kernel_init+0x18/0x12c
[    1.435589]  kernel_init from ret_from_fork+0x14/0x1c
[    1.435619] Exception stack(0xf081dfb0 to 0xf081dff8)
[    1.435641] dfa0:                                     00000000 
00000000 00000000 00000000
[    1.435667] dfc0: 00000000 00000000 00000000 00000000 00000000 
00000000 00000000 00000000
[    1.435692] dfe0: 00000000 00000000 00000000 00000000 00000013 00000000
[    1.435711] ---[ end trace 0000000000000000 ]---
[    1.435731] bcm2835-dma fe007000.dma: Failed to map zero page
[    1.435750] bcm2835-dma: probe of fe007000.dma failed with error -12
[    1.488044] Serial: 8250/16550 driver, 5 ports, IRQ sharing enabled
[    1.490574] printk: console [ttyS1] disabled

So i went back to 6.3, 6.2, 6.1 & 5.15 (enabling the config options 
manually on top of multi_v7_defconfig), but it shows the same broken 
behavior.

If i switch back to VMSPLIT_3G and keep ARM_LPAE, the system boots 
properly from SD card.

Any ideas what's the issue here or how to investigate further?

Best regards