Re: kworker/u4:1+tau stuck on G4 Sawtooth

[Bill deWindt <billd@dewindt.us>]

On 4/5/2025 6:20 PM, Brad Boyer wrote:
> If you can get a clean stack trace from that thread, you can see what
> code path in the kernel is causing it to sleep this way.

Thanks for the additional info on this issue. Here's the output from 
both of the machines I have here. One interesting thing I've been seeing 
from the beginning is that the 450Mhz machine always has the hung 
process at PID 19, and here's its output:

# cat /proc/19/stack
[<0>] __remove_hrtimer+0x5c/0xd8
[<0>] msleep+0x30/0x4c
[<0>] tau_work_func+0x24/0x68
[<0>] process_one_work+0x1b8/0x3d8
[<0>] worker_thread+0x288/0x3cc
[<0>] kthread+0xe0/0xe4
[<0>] start_kernel_thread+0x10/0x14

The PID for the same process on the 500Mhz machine varies at some boots, 
but is PID 9 on most, so here are 2 samples from 2 different boots:

# cat /proc/9/stack
[<0>] update_entity_lag+0x3c/0x174
[<0>] msleep+0x30/0x4c
[<0>] tau_work_func+0x24/0x68
[<0>] process_one_work+0x1b8/0x3d8
[<0>] worker_thread+0x288/0x3cc
[<0>] kthread+0xe0/0xe4
[<0>] start_kernel_thread+0x10/0x14

# cat /proc/787/stack
[<0>] dl_server_stop+0x40/0x60
[<0>] msleep+0x30/0x4c
[<0>] tau_work_func+0x24/0x68
[<0>] process_one_work+0x1b8/0x3d8
[<0>] worker_thread+0x288/0x3cc
[<0>] kthread+0xe0/0xe4
[<0>] start_kernel_thread+0x10/0x14

I am guessing (perhaps incorrectly?) that since all of the output from 
each trace above matches, with the exception of the first line, this 
gives an idea of where the tickle lies. Is there further digging I can 
do that would be useful?

Cheers!
Bill