Commit a257e974 authored by Zqiang's avatar Zqiang Committed by Tejun Heo
Browse files

sched_ext: Fix possible deadlock in the deferred_irq_workfn() 



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: default avatarZqiang <qiang.zhang@linux.dev>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent c87488a1

kernel/sched/ext.c

+1 −1
Original line number Diff line number Diff line
@@ -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))