On Tue, Sep 29, 2015 at 11:28:28AM +0200, Peter Zijlstra wrote:
> When we warn about a preempt_count leak; reset the preempt_count to
> the known good value such that the problem does not ripple forward.
>
> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
> ---
> kernel/exit.c | 4 +++-
> kernel/sched/core.c | 4 +++-
> 2 files changed, 6 insertions(+), 2 deletions(-)
>
> --- a/kernel/exit.c
> +++ b/kernel/exit.c
> @@ -706,10 +706,12 @@ void do_exit(long code)
> smp_mb();
> raw_spin_unlock_wait(&tsk->pi_lock);
>
> - if (unlikely(in_atomic()))
> + if (unlikely(in_atomic())) {
> pr_info("note: %s[%d] exited with preempt_count %d\n",
> current->comm, task_pid_nr(current),
> preempt_count());
> + preempt_count_set(PREEMPT_ENABLED);
> + }
>
> /* sync mm's RSS info before statistics gathering */
> if (tsk->mm)
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -2960,8 +2960,10 @@ static inline void schedule_debug(struct
> * schedule() atomically, we ignore that path. Otherwise whine
> * if we are scheduling when we should not.
> */
> - if (unlikely(in_atomic_preempt_off() && prev->state != TASK_DEAD))
> + if (unlikely(in_atomic_preempt_off() && prev->state != TASK_DEAD)) {
> __schedule_bug(prev);
> + preempt_count_set(PREEMPT_DISABLED);
That one would be a bit fragile if we kept PREEMPT_ACTIVE, but since we are
removing
it...
Reviewed-by: Frederic Weisbecker <fweis...@gmail.com>
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