[Intel-gfx] Regression on linux-next (next-20231013)

[Borah, Chaitanya Kumar]

 Hello Christian,
 
 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-20231013 [2], we are seeing the following RCU splat
 ```````````````````````````````````````````````````````````````````````````````
 <3> [511.395679] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
<3> [511.395716] rcu: 	Tasks blocked on level-1 rcu_node (CPUs 0-9): P6238
<3> [511.395934] rcu: 	(detected by 16, t=65002 jiffies, g=123977, q=439 ncpus=20)
<6> [511.395944] task:i915_selftest   state:R  running task     stack:10568 pid:6238  tgid:6238  ppid:1001   flags:0x00004002
 `````````````````````````````````````````````````````````````````````````````````
 
 Details log can be found in [3].
 
 After bisecting the tree, the following patch [4] seems to be the first "bad" commit
 
 `````````````````````````````````````````````````````````````````````````````````````````````````````````
commit 3a77344f50d847d51abb8629a6f181cb21684157
Author: Christian Brauner <brauner at kernel.org>
Date:   Fri Sep 29 08:45:59 2023 +0200

    file: convert to SLAB_TYPESAFE_BY_RCU
`````````````````````````````````````````````````````````````````````````````````````````````````````````
 
 We also verified that if we reset the tree to the parent commit the issue is not seen.
 
Could you please check how the commit results in the issue?

Thank you.

Regards

Chaitanya

 [1] https://intel-gfx-ci.01.org/tree/linux-next/combined-alt.html?
 [2] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?h=next-20231013
 [3] https://intel-gfx-ci.01.org/tree/linux-next/next-20231013/bat-dg2-11/igt@i915_selftest@live@mman.html
 [4] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?h=next-20231013&id=3a77344f50d847d51abb8629a6f181cb21684157