sched/core: Enable might_sleep() and smp_processor_id() checks early (1c3c5eab) · Commits · 戴 / test

might_sleep() and smp_processor_id() checks are enabled after the boot process is done. That hides bugs in the SMP bringup and driver initialization code. Enable it right when the scheduler starts working, i.e. when init task and kthreadd have been created and right before the idle task enables preemption. Tested-by:

Mark Rutland <mark.rutland@arm.com> Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by:

Mark Rutland <mark.rutland@arm.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20170516184736.272225698@linutronix.de Signed-off-by:

Ingo Molnar <mingo@kernel.org>

init/main.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -414,6 +414,16 @@ static noinline void __ref rest_init(void)
		rcu_read_lock();
		kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
		rcu_read_unlock();

		/*
		* Enable might_sleep() and smp_processor_id() checks.
		* They cannot be enabled earlier because with CONFIG_PRREMPT=y
		* kernel_thread() would trigger might_sleep() splats. With
		* CONFIG_PREEMPT_VOLUNTARY=y the init task might have scheduled
		* already, but it's stuck on the kthreadd_done completion.
		*/
		system_state = SYSTEM_SCHEDULING;

		complete(&kthreadd_done);

		/*

kernel/sched/core.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -6238,8 +6238,10 @@ void ___might_sleep(const char *file, int line, int preempt_offset)

		if ((preempt_count_equals(preempt_offset) && !irqs_disabled() &&
		!is_idle_task(current)) \|\|
		system_state != SYSTEM_RUNNING \|\| oops_in_progress)
		system_state == SYSTEM_BOOTING \|\| system_state > SYSTEM_RUNNING \|\|
		oops_in_progress)
		return;

		if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
		return;
		prev_jiffy = jiffies;

lib/smp_processor_id.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -28,7 +28,7 @@ notrace static unsigned int check_preemption_disabled(const char *what1,
		/*
		* It is valid to assume CPU-locality during early bootup:
		*/
		if (system_state != SYSTEM_RUNNING)
		if (system_state < SYSTEM_SCHEDULING)
		goto out;

		/*

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