Re: Regression on linux-next (next-20250312)

[Robin Murphy]

On 2025-03-14 9:17 am, Borah, Chaitanya Kumar wrote:
> Hello Robin,
>
> Hope you are doing well. I am Chaitanya from the linux graphics team in Intel.
>
> This mail is regarding a regression we are seeing in our CI runs[1] on linux-next repository.
>
> Since the version next-20250312 [2], we are seeing the following regression
>
> `````````````````````````````````````````````````````````````````````````````````
> <4>[    6.246790] reg-dummy reg-dummy: late IOMMU probe at driver bind, something fishy here!
> <4>[    6.246812] WARNING: CPU: 0 PID: 1 at drivers/iommu/iommu.c:449 __iommu_probe_device+0x140/0x570
> <4>[    6.246822] Modules linked in:
> <4>[    6.246830] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.14.0-rc6-next-20250312-next-20250312-g9fbcd7b32bf7+ #1
> <4>[    6.246838] Hardware name: Intel Corporation Arrow Lake Client Platform/MTL-S UDIMM 2DPC EVCRB, BIOS MTLSFWI1.R00.4400.D85.2410100007 10/10/2024
> <4>[    6.246847] RIP: 0010:__iommu_probe_device+0x140/0x570
> `````````````````````````````````````````````````````````````````````````````````
> Details log can be found in [3].
>
> After bisecting the tree, the following patch [4] seems to be the first "bad" commit
>
> `````````````````````````````````````````````````````````````````````````````````````````````````````````
> commit bcb81ac6ae3c2ef95b44e7b54c3c9522364a245c
> Author: Robin Murphy mailto:robin.murphy@xxxxxxx
> Date:   Fri Feb 28 15:46:33 2025 +0000
>
>      iommu: Get DT/ACPI parsing into the proper probe path
>
> `````````````````````````````````````````````````````````````````````````````````````````````````````````
>
> We also verified that if we revert the patch the issue is not seen.
>
> Could you please check why the patch causes this regression and provide a fix if necessary?

Yes, the warnings are false positives, and the fix is already in today's 
-next, see 73d2f10957f5 ("iommu: Don't warn prematurely about dodgy 
probes"). Sorry for the disruption.

Thanks,
Robin.

> Thank you.
>
> Regards
>
> Chaitanya
>
> [1] https://intel-gfx-ci.01.org/tree/linux-next/combined-alt.html?
> [2] https://web.git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?h=next-20250312
> [3] https://intel-gfx-ci.01.org/tree/linux-next/next-20250312/bat-arls-6/boot0.txt
> [4] https://web.git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?h=next-20250312&id=bcb81ac6ae3c2ef95b44e7b54c3c9522364a245c