Commit-ID:  185b42420b0948dfc00af6cc5d93aa00b7fef581
Gitweb:     http://git.kernel.org/tip/185b42420b0948dfc00af6cc5d93aa00b7fef581
Author:     Peter Zijlstra <[email protected]>
AuthorDate: Tue, 29 Sep 2015 11:28:28 +0200
Committer:  Ingo Molnar <[email protected]>
CommitDate: Tue, 29 Sep 2015 12:27:40 +0200

sched/core: Robustify preemption leak checks

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) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
 kernel/exit.c       | 4 +++-
 kernel/sched/core.c | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index ea95ee1..443677c 100644
--- 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)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ecd585c..d1dec5d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2953,8 +2953,10 @@ static inline void schedule_debug(struct task_struct 
*prev)
         * 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);
+       }
        rcu_sleep_check();
 
        profile_hit(SCHED_PROFILING, __builtin_return_address(0));
--
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