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| author |   Peter Zijlstra <peterz@infradead.org> | 2015-09-28 17:57:39 +0200 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2015-10-06 17:08:17 +0200 |
| commit | 1dc0fffc48af94513e621f95dff730ed4f7317ec (patch) | |
| tree | 602dbd67f0565830ea99196d71e7f47b17d849e3 | |
| parent | sched/core: Stop setting PREEMPT_ACTIVE (diff) | |
| download | linux-dev-1dc0fffc48af94513e621f95dff730ed4f7317ec.tar.xz linux-dev-1dc0fffc48af94513e621f95dff730ed4f7317ec.zip | |
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.
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.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | kernel/exit.c | 4 | ||||
| -rw-r--r-- | kernel/sched/core.c | 4 |
2 files changed, 6 insertions, 2 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index ea95ee1b5ef7..443677c8efe6 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 6344d82a84f6..d6989f85c641 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2968,8 +2968,10 @@ static inline void schedule_debug(struct task_struct *prev) 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)); |