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Subjectdebug rsdl 0.33
Date
On Saturday 24 March 2007 08:45, Con Kolivas wrote:
> On Friday 23 March 2007 23:28, Andy Whitcroft wrote:
> > Andy Whitcroft wrote:
> > > Con Kolivas wrote:
> > >> On Friday 23 March 2007 05:17, Andy Whitcroft wrote:
> > >>> Ok, I have yet a third x86_64 machine is is blowing up with the
> > >>> latest 2.6.21-rc4-mm1+hotfixes+rsdl-0.32 but working with
> > >>> 2.6.21-rc4-mm1+hotfixes-RSDL. I have results on various hotfix
> > >>> levels so I have just fired off a set of tests across the affected
> > >>> machines on that latest hotfix stack plus the RSDL backout and the
> > >>> results should be in in the next hour or two.
> > >>>
> > >>> I think there is a strong correlation between RSDL and these hangs.
> > >>> Any suggestions as to the next step.
> > >>
> > >> Found a nasty in requeue_task
> > >> + if (list_empty(old_array->queue + old_prio))
> > >> + __clear_bit(old_prio, p->array->prio_bitmap);
> > >>
> > >> see anything wrong there? I do :P
> > >>
> > >> I'll queue that up with the other changes pending and hopefully that
> > >> will fix your bug.
> > >
> > > Tests queued with your rdsl-0.33 patch (I am assuming its in there).
> > > Will let you know how it looks.
> >
> > Hmmm, this is good for the original machine (as was 0.32) but not for
> > either of the other two. I am seeing panics as below on those two.
>
> This machine seems most sensitive to it (first column):
> elm3b6
> amd64
> newisys
> 4cpu
> config: amd64
>
> Can you throw this debugging patch at it please? The console output might
> be very helpful. On top of sched-rsdl-0.33 thanks!

Better yet this one which checks the expired array as well and after
pull_task.

If anyone's getting a bug they think might be due to rsdl please try this (on
rsdl 0.33).

---
kernel/sched.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)
Index: linux-2.6.21-rc4-mm1/kernel/sched.c
===================================================================
--- linux-2.6.21-rc4-mm1.orig/kernel/sched.c 2007-03-24 08:32:19.000000000 +1100
+++ linux-2.6.21-rc4-mm1/kernel/sched.c 2007-03-24 10:22:59.000000000 +1100
@@ -659,6 +659,35 @@ static inline void set_task_entitlement(
p->time_slice = p->quota;
}

+static int debug_rqbitmap(struct rq *rq)
+{
+ struct list_head *queue;
+ int idx = 0, error = 0;
+ struct prio_array *array;
+
+ for (idx = 0; idx < MAX_PRIO; idx++) {
+ array = rq->active;
+ queue = array->queue + idx;
+ if (!list_empty(queue)) {
+ if (!test_bit(idx, rq->dyn_bitmap)) {
+ __set_bit(idx, rq->dyn_bitmap);
+ error = 1;
+ printk(KERN_ERR "MISSING DYNAMIC BIT %d\n", idx);
+ }
+ }
+ array = rq->expired;
+ queue = array->queue + idx;
+ if (!list_empty(queue)) {
+ if (!test_bit(idx, rq->exp_bitmap)) {
+ __set_bit(idx, rq->exp_bitmap);
+ error = 1;
+ printk(KERN_ERR "MISSING EXPIRED BIT %d\n", idx);
+ }
+ }
+ }
+ return error;
+}
+
/*
* There is no specific hard accounting. The dynamic bits can have
* false positives. rt_tasks can only be on the active queue.
@@ -679,6 +708,7 @@ static void dequeue_task(struct task_str
list_del_init(&p->run_list);
if (list_empty(p->array->queue + p->prio))
__clear_bit(p->prio, p->array->prio_bitmap);
+ WARN_ON(debug_rqbitmap(rq));
}

/*
@@ -797,12 +827,14 @@ static void enqueue_task(struct task_str
{
__enqueue_task(p, rq);
list_add_tail(&p->run_list, p->array->queue + p->prio);
+ WARN_ON(debug_rqbitmap(rq));
}

static inline void enqueue_task_head(struct task_struct *p, struct rq *rq)
{
__enqueue_task(p, rq);
list_add(&p->run_list, p->array->queue + p->prio);
+ WARN_ON(debug_rqbitmap(rq));
}

/*
@@ -820,6 +852,7 @@ static void requeue_task(struct task_str
__clear_bit(old_prio, old_array->prio_bitmap);
set_dynamic_bit(p, rq);
}
+ WARN_ON(debug_rqbitmap(rq));
}

/*
@@ -906,6 +939,7 @@ static inline void __activate_task(struc
{
enqueue_task(p, rq);
inc_nr_running(p, rq);
+ WARN_ON(debug_rqbitmap(rq));
}

/*
@@ -1006,6 +1040,7 @@ static void deactivate_task(struct task_
{
dec_nr_running(p, rq);
dequeue_task(p, rq);
+ WARN_ON(debug_rqbitmap(rq));
}

/*
@@ -1718,9 +1753,11 @@ void fastcall wake_up_new_task(struct ta
* Parent and child are on different CPUs, now get the
* parent runqueue to update the parent's ->flags:
*/
+ WARN_ON(debug_rqbitmap(rq));
task_rq_unlock(rq, &flags);
this_rq = task_rq_lock(current, &flags);
}
+ WARN_ON(debug_rqbitmap(this_rq));
task_rq_unlock(this_rq, &flags);
}

@@ -2124,6 +2161,8 @@ static void pull_task(struct rq *src_rq,
enqueue_pulled_task(src_rq, this_rq, p);
p->timestamp = (p->timestamp - src_rq->most_recent_timestamp)
+ this_rq->most_recent_timestamp;
+ WARN_ON(debug_rqbitmap(src_rq));
+ WARN_ON(debug_rqbitmap(this_rq));
try_preempt(p, this_rq);
}

@@ -3357,6 +3396,7 @@ static inline void major_prio_rotation(s
rq->dyn_bitmap = rq->active->prio_bitmap;
rq->best_static_prio = MAX_PRIO - 1;
rq->prio_rotation++;
+ WARN_ON(debug_rqbitmap(rq));
}

/*
@@ -3399,6 +3439,8 @@ static inline void rotate_runqueue_prior
}
memset(rq->prio_quota, 0, ARRAY_SIZE(rq->prio_quota));
major_prio_rotation(rq);
+ WARN_ON(debug_rqbitmap(rq));
+
} else {
/* Minor rotation */
new_prio_level = rq->prio_level + 1;
@@ -3409,6 +3451,7 @@ static inline void rotate_runqueue_prior
__set_bit(new_prio_level, rq->dyn_bitmap);
}
rq_quota(rq, rq->prio_level) = 0;
+ WARN_ON(debug_rqbitmap(rq));
}
rq->prio_level = new_prio_level;
/*
@@ -3431,6 +3474,10 @@ static void task_running_tick(struct rq
return;

spin_lock(&rq->lock);
+ if (!p->time_slice) {
+ printk(KERN_ERR "NO TIME_SLICE IN TRT \n");
+ p->time_slice++;
+ }
/*
* Accounting is performed by both the task and the runqueue. This
* allows frequently sleeping tasks to get their proper quota of
@@ -3460,6 +3507,7 @@ static void task_running_tick(struct rq
set_tsk_need_resched(p);
}
out_unlock:
+ WARN_ON(debug_rqbitmap(rq));
spin_unlock(&rq->lock);
}

@@ -3479,6 +3527,7 @@ void scheduler_tick(void)

if (!idle_at_tick)
task_running_tick(rq, p, 1);
+ WARN_ON(debug_rqbitmap(rq));
#ifdef CONFIG_SMP
update_load(rq);
rq->idle_at_tick = idle_at_tick;
@@ -3548,6 +3597,7 @@ static inline struct task_struct *next_d
struct prio_array *array = rq->active;
int expirations = 0;

+ WARN_ON(debug_rqbitmap(rq));
retry:
if (idx >= MAX_PRIO) {
BUG_ON(++expirations > 1);
@@ -3601,6 +3651,7 @@ retry:
if (next->static_prio < rq->best_static_prio &&
next->policy != SCHED_BATCH)
rq->best_static_prio = next->static_prio;
+ WARN_ON(debug_rqbitmap(rq));
return next;
}

--
-ck
-
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