From 1c3c5eab171590f86edd8d31389d61dd1efe3037 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner <tglx@linutronix.de> Date: Tue, 16 May 2017 20:42:48 +0200 Subject: [PATCH] sched/core: Enable might_sleep() and smp_processor_id() checks early 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 ++++++++++ kernel/sched/core.c | 4 +++- lib/smp_processor_id.c | 2 +- 3 files changed, 14 insertions(+), 2 deletions(-) diff --git a/init/main.c b/init/main.c index badae3bf08f16..df58a416dd1da 100644 --- a/init/main.c +++ b/init/main.c @@ -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); /* diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 877241e9f2b0d..c3e50cada84d8 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -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; diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c index 690d75b132fa7..2fb007be02125 100644 --- a/lib/smp_processor_id.c +++ b/lib/smp_processor_id.c @@ -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; /* -- GitLab