Re: [PATCH] sched: dynamic: Fix preemption model strings

[Mete Durlu]

On 02/09/2026 12:16, Mark Rutland wrote:
> We recently removed the enum values 'preempt_dynamic_none' and
> 'preempt_dynamic_voluntary', but forgot to update preempt_modes[]
> accordingly. Due to this, preempt_model_str() and sched_dynamic_show()
> produce incorrect output, with the wrong preemption model string in
> backtraces, and empty output for /sys/kernel/debug/sched/preempt.
>
> Update preempt_modes[] to account for the removed enum values. Given
> that CONFIG_PREEMPT_DYNAMIC now depends on CONFIG_ARCH_HAS_PREEMPT_LAZY,
> and given that only 'preempt_dynamic_full' and 'preempt_dynamic_lazy'
> remain, sched_dynamic_show() no longer needs to skip any model strings.
>
> Reported-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
> Fixes: 9650ce11f2e3 ("sched: dynamic: Simplify preempt model accessors")
> Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Hi,

I did a quick test on s390.

$ echo full > preempt
$ cat preempt
(full) lazy

$ echo lazy > preempt
$ cat preempt
full (lazy)

The sched_dynamic_show() output looks correct now, and the
code looks much nicer without those conditional indices.
Feel free to put my tested by.

Tested-by: Mete Durlu <meted@xxxxxxxxxxxxx>