Regression on linux-next (next-20260324 )

["Borah, Chaitanya Kumar" <chaitanya.kumar.borah@intel.com>]

Hello Matthew,

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-20260324 [2], we are seeing the following regression

`````````````````````````````````````````````````````````````````````````````````
<5>[  157.361977] [IGT] Inactivity timeout exceeded. Killing the current 
test with SIGQUIT.
<6>[  157.362097] sysrq: HELP : loglevel(0-9) reboot(b) crash(c) 
show-all-locks(d) terminate-all-tasks(e) memory-full-oom-kill(f) 
kill-all-tasks(i) thaw-filesystems(j) sak(k) 
show-backtrace-all-active-cpus(l) show-memory-usage(m) 
nice-all-RT-tasks(n) poweroff(o) show-registers(p) show-all-timers(q) 
unraw(r) sync(s) show-task-states(t) unmount(u) force-fb(v) 
show-blocked-tasks(w) dump-ftrace-buffer(z) replay-kernel-logs(R)
<6>[  157.399543] sysrq: Show State
<6>[  157.403061] task:systemd         state:S stack:0     pid:1 
tgid:1     ppid:0      task_flags:0x400100 flags:0x00080000
<6>[  157.403067] Call Trace:
<6>[  157.403069]  <TASK>
<6>[  157.403072]  __schedule+0x5d7/0x1ef0
<6>[  157.403078]  ? lock_acquire+0xc4/0x300
<6>[  157.403084]  ? schedule+0x10e/0x180
<6>[  157.403087]  ? lock_release+0xcd/0x2b0
<6>[  157.403092]  schedule+0x3a/0x180
<6>[  157.403094]  schedule_hrtimeout_range_clock+0x112/0x120
<6>[  157.403097]  ? do_epoll_wait+0x3e4/0x5b0
<6>[  157.403102]  ? lock_release+0xcd/0x2b0
<6>[  157.403104]  ? _raw_spin_unlock_irq+0x27/0x70
<6>[  157.403106]  ? do_epoll_wait+0x3e4/0x5b0
<6>[  157.403110]  schedule_hrtimeout_range+0x13/0x30
`````````````````````````````````````````````````````````````````````````````````
Details log can be found in [3].

After bisecting the tree, the following patch [4] seems to be the first 
"bad" commit

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commit 25500ba7e77ce9d3d9b5a1929d41a2ee2e23f6fe
Author: Matthew Wilcox (Oracle) willy@infradead.org
Date:   Thu Mar 5 19:55:43 2026 +0000

     locking/mutex: Remove the list_head from struct mutex
`````````````````````````````````````````````````````````````````````````````````````````````````````````

We could not revert the patch because of merge conflict but resetting to 
the parent of the commit seems to fix the issue.

Could you please check why the patch causes this regression and provide 
a fix if necessary?

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-20260324
[3]
https://intel-gfx-ci.01.org/tree/linux-next/next-20260326/bat-arlh-2/dmesg0.txt
[4] 
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?h=next-20231130&id=f4acfcd4deb158b96595250cc332901b282d15b0