On Mon, Oct 05, 2020 at 12:49:17PM +0200, Frederic Weisbecker wrote:
> Detect calls to schedule() between user_enter() and user_exit(). Those
> are symptoms of early entry code that either forgot to protect a call
> to schedule() inside exception_enter()/exception_exit() or, in the case
> of HAVE_CONTEXT_TRACKING_OFFSTACK, enabled interrupts or preemption in
> a wrong spot.
>
> Signed-off-by: Frederic Weisbecker <frede...@kernel.org>
> Cc: Marcelo Tosatti <mtosa...@redhat.com>
> Cc: Paul E. McKenney <paul...@kernel.org>
> Cc: Peter Zijlstra <pet...@infradead.org>
> Cc: Phil Auld <pa...@redhat.com>
> Cc: Thomas Gleixner <t...@linutronix.de>
> ---
> kernel/sched/core.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 2d95dc3f4644..d31a79e073e3 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -4295,6 +4295,7 @@ static inline void schedule_debug(struct task_struct
> *prev, bool preempt)
> preempt_count_set(PREEMPT_DISABLED);
> }
> rcu_sleep_check();
> + WARN_ON_ONCE(ct_state() == CONTEXT_USER);
SCHED_WARN_ON() ?
No point in unconditionally polluting that path. Although, per MeL, we
should probably invest in CONFIG_SCHED_DEBUG_I_MEANS_IT :/
