sched_ext, rcu: Upgrade RCU stall paths to report cpumask of stalled CPUs

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scx_rcu_cpu_stall() previously recorded the detector CPU rather than the
stalled one, and the expedited grace period path had no stalled CPU to
report at all.

Thread a cpumask through panic_on_rcu_stall() and scx_rcu_cpu_stall()
to capture all stalled CPUs. Report cpumask_first() as exit_cpu and the
full CPU list in the exit message. Task-only stalls yield exit_cpu = -1.

Store the stall mask in scx_sched rather than scx_exit_info, keeping the
BPF-visible struct unchanged. scx_dump_state() reads sch->stall_cpus
directly and dumps all stalled CPUs first to avoid losing them to
truncation.

Signed-off-by: Cheng-Yang Chou <yphbchou0911@gmail.com>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

...

This commit is contained in:

Cheng-Yang Chou 2026-06-10 23:26:56 +08:00 • committed by Tejun Heo

parent da428d572e

commit 252891d03d

6 changed files with 83 additions and 16 deletions

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4

include/linux/sched/ext.h

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3

kernel/rcu/tree.c

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5

kernel/rcu/tree_exp.h

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13

kernel/rcu/tree_stall.h

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73

kernel/sched/ext/ext.c

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1

kernel/sched/ext/internal.h

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