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rcu-tasks: Move RCU Tasks self-tests to core_initcall()

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The timer and hrtimer softirq processing has moved to dedicated threads
for kernels built with CONFIG_IRQ_FORCED_THREADING=y.  This results in
timers not expiring until later in early boot, which in turn causes the
RCU Tasks self-tests to hang in kernels built with CONFIG_PROVE_RCU=y,
which further causes the entire kernel to hang.  One fix would be to
make timers work during this time, but there are no known users of RCU
Tasks grace periods during that time, so no justification for the added
complexity.  Not yet, anyway.

This commit therefore moves the call to rcu_init_tasks_generic() from
kernel_init_freeable() to a core_initcall().  This works because the
timer and hrtimer kthreads are created at early_initcall() time.

Fixes: 49a17639508c3 ("softirq: Use a dedicated thread for timer wakeups on PREEMPT_RT.")
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: <linux-trace-kernel@vger.kernel.org>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
This commit is contained in:
Paul E. McKenney 2024-12-20 13:09:30 -08:00 committed by Boqun Feng
parent 85aad7cc41
commit 23c22d9156
3 changed files with 4 additions and 8 deletions
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6
include/linux/rcupdate.h
View File

@ -121,12 +121,6 @@ void rcu_init(void);
extern int rcu_scheduler_active;
void rcu_sched_clock_irq(int user);
#ifdef CONFIG_TASKS_RCU_GENERIC
void rcu_init_tasks_generic(void);
#else
static inline void rcu_init_tasks_generic(void) { }
#endif
#ifdef CONFIG_RCU_STALL_COMMON
void rcu_sysrq_start(void);
void rcu_sysrq_end(void);

1
init/main.c
View File

@ -1553,7 +1553,6 @@ static noinline void __init kernel_init_freeable(void)
init_mm_internals();
rcu_init_tasks_generic();
do_pre_smp_initcalls();
lockup_detector_init();

5
kernel/rcu/tasks.h
View File

@ -2256,7 +2256,7 @@ void __init tasks_cblist_init_generic(void)
#endif
}
void __init rcu_init_tasks_generic(void)
static int __init rcu_init_tasks_generic(void)
{
#ifdef CONFIG_TASKS_RCU
rcu_spawn_tasks_kthread();
@ -2272,7 +2272,10 @@ void __init rcu_init_tasks_generic(void)
// Run the self-tests.
rcu_tasks_initiate_self_tests();
return 0;
}
core_initcall(rcu_init_tasks_generic);
#else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
static inline void rcu_tasks_bootup_oddness(void) {}