Den fre. 26. feb. 2021 kl. 15.14 skrev Bruno Thomsen [off-list ref]:

Den tor. 25. feb. 2021 kl. 10.57 skrev Oliver Neukum [off-list ref]:

quoted

Am Mittwoch, den 24.02.2021, 16:21 +0100 schrieb Bruno Thomsen:

Hi,

quoted

No, this is not a regression from 5.10. It seems that many attempts to
fix cdc-acm in the 5.x kernel series have failed to fix the root cause of
these oops. I have not seen this on 4.14 and 4.19, but I have observed
it on at least 5.3 and newer kernels in slight variations.
I guess this is because cdc-acm is very common in the embedded
ARM world and rarely used on servers or laptops. Combined with
ARM devices still commonly use 4.x LTS kernels. Not sure if
hardening options on the kernel has increased change of reproducing
oops.

OK, so this is not an additional problem.
According to your logs, an URB that should have been killed wasn't.

Thanks for looking into this bug rapport.

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quoted

I am ready to test new patches and will continue to report oops

Could you test the attached patches?

Yes, I am already running tests on the patches.
I have not seen any oops yet and it seems the USB cdc-acm driver is still
working as intended.

The only notable trace I have seen is this new error from the cdc-acm driver
but everything kept on working.
kernel: cdc_acm 1-1.1:1.7: acm_start_wb - usb_submit_urb(write bulk) failed: -19

Other then that I see this common error (should probably be a warning) during
device enumeration:
kernel: cdc_acm 1-1.2:1.0: failed to set dtr/rts

I will post an update next week when the patches have survived some
more runtime.

Tested-by: Bruno Thomsen <redacted>

I have not observed any oops with patches applied. Patches have seen
more than 10 weeks of runtime testing across multiple devices.

/Bruno

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