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.
This is most important on x86 which has a per cpu preempt_count that is not saved/restored (after this series). So if you schedule with an invalid (!2*PREEMPT_DISABLE_OFFSET) preempt_count the next task is messed up too. Enforcing this invariant limits the borkage to just the one task. Reviewed-by: Frederic Weisbecker <[email protected]> Reviewed-by: Thomas Gleixner <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> --- 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 @@ -2968,8 +2968,10 @@ static inline void schedule_debug(struct BUG_ON(unlikely(task_stack_end_corrupted(prev))); #endif - if (unlikely(in_atomic_preempt_off())) + if (unlikely(in_atomic_preempt_off())) { __schedule_bug(prev); + preempt_count_set(PREEMPT_DISABLED); + } rcu_sleep_check(); profile_hit(SCHED_PROFILING, __builtin_return_address(0)); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
