Re: [PATCH] sched_ext:SCX is preemptible by the Fair scheduler

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] The patch adds `SCX_CPU_PREEMPT_FAIR` to `enum scx_cpu_preempt_reason` in `kernel/sched/ext_internal.h`, but fails to update the checked-in autogenerated BPF tool headers in `tools/sched_ext/include/scx/enum_defs.autogen.h`.
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commit 0e9cc05c20430d666c8c1a1d7ea0741d9c28b2d3
Author: Cui Jian <cjian720@163.com>

sched_ext:SCX is preemptible by the Fair scheduler

This commit adds a new preemption reason, SCX_CPU_PREEMPT_FAIR, to distinguish
when a sched_ext task is preempted by the Fair scheduler. It updates the
internal enum and mapping function to improve observability and diagnostics.

> diff --git a/kernel/sched/ext_internal.h b/kernel/sched/ext_internal.h
> index a075732d4430d..3ce07bec58a55 100644
> --- a/kernel/sched/ext_internal.h
> +++ b/kernel/sched/ext_internal.h
> @@ -241,6 +241,8 @@ enum scx_cpu_preempt_reason {
>  	SCX_CPU_PREEMPT_DL,
>  	/* next task is being scheduled by &sched_class_stop */
>  	SCX_CPU_PREEMPT_STOP,
> +	/* next task is being scheduled by &sched_class_fair*/
> +	SCX_CPU_PREEMPT_FAIR,

[Severity: Medium]
Should tools/sched_ext/include/scx/enum_defs.autogen.h be regenerated
and included in this patch?

When adding a new value to enum scx_cpu_preempt_reason, the autogenerated
BPF tool headers typically need updating so downstream BPF schedulers can
use feature detection macros like HAVE_SCX_CPU_PREEMPT_FAIR. 

Without this update, BPF applications cannot conditionally check for this
new preemption feature across different kernel versions.

>  	/* unknown reason for SCX being preempted */
>  	SCX_CPU_PREEMPT_UNKNOWN,
>  };

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Sashiko AI review · https://sashiko.dev/#/patchset/20260612161403.105775-1-cjian720@163.com?part=1