ARM_LPAE + VMSPLIT_2G cause swiotlb warning on Raspberry Pi 4

Wed May 17 03:24:43 PDT 2023

Hi Robin,

Am 17.05.23 um 12:06 schrieb Robin Murphy:
> On 2023-05-17 07:23, Stefan Wahren wrote:
>> Hi,
>>
>> Am 17.05.23 um 00:17 schrieb Florian Fainelli:

...

>>
>> [    1.419785] ------------[ cut here ]------------
>> [    1.419811] WARNING: CPU: 2 PID: 1 at include/linux/dma-direct.h:36 
>> dma_map_page_attrs+0x360/0x368
>> [    1.419862] Unable to xlate: 0x000000006ffd9000
> 
> This suggests that the SWIOTLB buffer itself has somehow been allocated 
> from ZONE_NORMAL rather than ZONE_DMA (unfortunately you trimmed the log 
> line from swiotlb_print_info() saying exactly where it is). That can't 
> happen with VMSPLIT_3G where we have less than 1GB of lowmem anyway, 
> which explains that difference. I don't have an idea off-hand why LPAE 
> would affect it.

This one?

[    0.000000] Dentry cache hash table entries: 262144 (order: 8, 
1048576 bytes, linear)
[    0.000000] Inode-cache hash table entries: 131072 (order: 7, 524288 
bytes, linear)
[    0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[    0.000000] software IO TLB: area num 4.
[    0.000000] software IO TLB: mapped [mem 
0x0000000069e7f000-0x000000006de7f000] (64MB)
[    0.000000] Memory: 3856044K/4050944K available (16384K kernel code, 
2481K rwdata, 6284K rodata, 2048K init, 430K bss, 129364K reserved, 
65536K cma-reserved, 2293760K highmem)
[    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1

> 
> Thanks,
> Robin.
> 
>> [    1.419879] Modules linked in:
>> [    1.419902] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 6.3.0-dirty #11
>> [    1.419926] Hardware name: BCM2711
>> [    1.419950]  unwind_backtrace from show_stack+0x10/0x14
>> [    1.419990]  show_stack from dump_stack_lvl+0x40/0x4c
>> [    1.420031]  dump_stack_lvl from __warn+0x7c/0x124
>> [    1.420077]  __warn from warn_slowpath_fmt+0x118/0x174
>> [    1.420122]  warn_slowpath_fmt from dma_map_page_attrs+0x360/0x368
>> [    1.420169]  dma_map_page_attrs from bcm2835_dma_probe+0x1d8/0x41c
>> [    1.420215]  bcm2835_dma_probe from platform_probe+0x5c/0xbc
>> [    1.420262]  platform_probe from really_probe+0xc8/0x2dc
>> [    1.420300]  really_probe from __driver_probe_device+0x84/0xe4
>> [    1.420335]  __driver_probe_device from driver_probe_device+0x30/0x104
>> [    1.420369]  driver_probe_device from __driver_attach+0x90/0x174
>> [    1.420403]  __driver_attach from bus_for_each_dev+0x6c/0xb4
>> [    1.420435]  bus_for_each_dev from bus_add_driver+0xcc/0x1cc
>> [    1.420465]  bus_add_driver from driver_register+0x7c/0x118
>> [    1.420498]  driver_register from do_one_initcall+0x40/0x1e0
>> [    1.420534]  do_one_initcall from kernel_init_freeable+0x1b8/0x220
>> [    1.420578]  kernel_init_freeable from kernel_init+0x18/0x12c
>> [    1.420627]  kernel_init from ret_from_fork+0x14/0x1c
>> [    1.420662] Exception stack(0xf081dfb0 to 0xf081dff8)
>> [    1.420684] dfa0:                                     00000000 
>> 00000000 00000000 00000000
>> [    1.420710] dfc0: 00000000 00000000 00000000 00000000 00000000 
>> 00000000 00000000 00000000
>> [    1.420734] dfe0: 00000000 00000000 00000000 00000000 00000013 
>> 00000000
>> [    1.420753] ---[ end trace 0000000000000000 ]---
>> [    1.420771] ------------[ cut here ]------------
>> [    1.420785] WARNING: CPU: 2 PID: 1 at include/linux/dma-direct.h:36 
>> swiotlb_map+0x1dc/0x3e4
>> [    1.420829] Unable to xlate: 0x000000006ffd9000
>> [    1.420844] Modules linked in:
>> [    1.420863] CPU: 2 PID: 1 Comm: swapper/0 Tainted: G        W 
>>   6.3.0-dirty #11
>> [    1.420890] Hardware name: BCM2711
>> [    1.420906]  unwind_backtrace from show_stack+0x10/0x14
>> [    1.420942]  show_stack from dump_stack_lvl+0x40/0x4c
>> [    1.420978]  dump_stack_lvl from __warn+0x7c/0x124
>> [    1.421021]  __warn from warn_slowpath_fmt+0x118/0x174
>> [    1.421066]  warn_slowpath_fmt from swiotlb_map+0x1dc/0x3e4
>> [    1.421114]  swiotlb_map from dma_map_page_attrs+0x210/0x368
>> [    1.421159]  dma_map_page_attrs from bcm2835_dma_probe+0x1d8/0x41c
>> [    1.421201]  bcm2835_dma_probe from platform_probe+0x5c/0xbc
>> [    1.421244]  platform_probe from really_probe+0xc8/0x2dc
>> [    1.421281]  really_probe from __driver_probe_device+0x84/0xe4
>> [    1.421314]  __driver_probe_device from driver_probe_device+0x30/0x104
>> [    1.421348]  driver_probe_device from __driver_attach+0x90/0x174
>> [    1.421382]  __driver_attach from bus_for_each_dev+0x6c/0xb4
>> [    1.421413]  bus_for_each_dev from bus_add_driver+0xcc/0x1cc
>> [    1.421442]  bus_add_driver from driver_register+0x7c/0x118
>> [    1.421475]  driver_register from do_one_initcall+0x40/0x1e0
>> [    1.421509]  do_one_initcall from kernel_init_freeable+0x1b8/0x220
>> [    1.421551]  kernel_init_freeable from kernel_init+0x18/0x12c
>> [    1.421599]  kernel_init from ret_from_fork+0x14/0x1c
>> [    1.421634] Exception stack(0xf081dfb0 to 0xf081dff8)
>> [    1.421654] dfa0:                                     00000000 
>> 00000000 00000000 00000000
>> [    1.421679] dfc0: 00000000 00000000 00000000 00000000 00000000 
>> 00000000 00000000 00000000
>> [    1.421704] dfe0: 00000000 00000000 00000000 00000000 00000013 
>> 00000000
>> [    1.421722] ---[ end trace 0000000000000000 ]---
>> [    1.421747] ------------[ cut here ]------------
>>
>>>
>>> Thanks!
> 
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