might_sleep() 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. Signed-off-by: Thomas Gleixner --- init/main.c | 2 ++ kernel/sched/core.c | 4 +++- 2 files changed, 5 insertions(+), 1 deletion(-) --- a/init/main.c +++ b/init/main.c @@ -410,6 +410,8 @@ static noinline void __ref rest_init(voi * at least once to get things moving: */ init_idle_bootup_task(current); + /* Enable might_sleep() checks */ + system_state = SYSTEM_BOOTING_UP; schedule_preempt_disabled(); /* Call into cpu_idle with preempt disabled */ cpu_startup_entry(CPUHP_ONLINE); --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6226,8 +6226,10 @@ void ___might_sleep(const char *file, in 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;