Re: [debug patch] printk: Add a printk killswitch to robustify NMIwatchdog messages

From: Ingo Molnar
Date: Sun Jun 05 2011 - 11:13:50 EST



* Arne Jansen <lists@xxxxxxxxxxxxxx> wrote:

> sched.c:934: in function __task_rq_lock
> lockdep_assert_held(&p->pi_lock);

Oh. Could you remove that line with the patch below - does it result
in a working system?

Now, this patch alone just removes a debugging check - but i'm not
sure the debugging check is correct - we take the pi_lock in a raw
way - which means it's not lockdep covered.

So how can lockdep_assert_held() be called on it?

Thanks,

Ingo

diff --git a/kernel/sched.c b/kernel/sched.c
index fd18f39..a32316b 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -938,8 +938,6 @@ static inline struct rq *__task_rq_lock(struct task_struct *p)
{
struct rq *rq;

- lockdep_assert_held(&p->pi_lock);
-
for (;;) {
rq = task_rq(p);
raw_spin_lock(&rq->lock);
--
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