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sched_ext: Fix possible deadlock in the deferred_irq_workfn()

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For PREEMPT_RT=y kernels, the deferred_irq_workfn() is executed in
the per-cpu irq_work/* task context and not disable-irq, if the rq
returned by container_of() is current CPU's rq, the following scenarios
may occur:

lock(&rq->__lock);
<Interrupt>
  lock(&rq->__lock);

This commit use IRQ_WORK_INIT_HARD() to replace init_irq_work() to
initialize rq->scx.deferred_irq_work, make the deferred_irq_workfn()
is always invoked in hard-irq context.

Signed-off-by: Zqiang <qiang.zhang@linux.dev>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Zqiang 2025-11-13 19:43:55 +08:00 committed by Tejun Heo
parent c87488a123
commit a257e97421
1 changed files with 1 additions and 1 deletions
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2
kernel/sched/ext.c
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@ -5321,7 +5321,7 @@ void __init init_sched_ext_class(void)
BUG_ON(!zalloc_cpumask_var_node(&rq->scx.cpus_to_kick_if_idle, GFP_KERNEL, n));
BUG_ON(!zalloc_cpumask_var_node(&rq->scx.cpus_to_preempt, GFP_KERNEL, n));
BUG_ON(!zalloc_cpumask_var_node(&rq->scx.cpus_to_wait, GFP_KERNEL, n));
init_irq_work(&rq->scx.deferred_irq_work, deferred_irq_workfn);
rq->scx.deferred_irq_work = IRQ_WORK_INIT_HARD(deferred_irq_workfn);
init_irq_work(&rq->scx.kick_cpus_irq_work, kick_cpus_irq_workfn);
if (cpu_online(cpu))