On Monday 26 March 2007 08:49, Con Kolivas wrote:
> On Monday 26 March 2007 04:28, Torsten Kaiser wrote:
> > On 3/24/07, Con Kolivas <[EMAIL PROTECTED]> wrote:
> > > kernel/sched.c | 51
> > > +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51
> > > insertions(+)
> >
> > 2.6.21-rc4-mm1 also fails for me.
> >
> > I tried pure 2.6.21-rc4-mm1, +hotfixes, +hotfixes+rsdl33 and at last
> > also added above debug patch.
>
> Thank you very much for the effort!
>
> > The oops from with the debug-patch added:
> > [ 65.426126] Freeing unused kernel memory: 312k freed
> > (on the console the system is starting up, getting until "Letting udev
> > process events ...")
> > [ 66.665611] Unable to handle kernel NULL pointer dereference at
> > 0000000000000020 RIP:
> > [ 66.682030] [<ffffffff8026167c>] __sched_text_start+0x4dc/0xa0e
>
> The debug patch didn't do anything. This means it is not an unset bitmap
> problem at all otherwise it should have self corrected itself.
>
> > The system in x86_64, two 2218 on a MCP55 nvidia chipset.
> >
> > 2.6.21-rc3-mm1 works fine.
> >
> > (gdb) list *0xffffffff8026167c
> > 0xffffffff8026167c is in schedule (kernel/sched.c:3619).
>
> next = list_entry(queue->next, struct task_struct, run_list);
> rq->prio_level = idx;
>
> > 3614 /*
> > 3615 * When the task is chosen it is checked to see if its
> > quota has been
> > 3616 * added to this runqueue level which is only performed
> > once per 3617 * level per major rotation for each running
> > task. 3618 */
> > 3619 if (next->rotation != rq->prio_rotation) {
>
> Urgh. Dereferencing there? That can only be next that's deferencing meaning
> the run_list entry is bogus. That should only ever be done under runqueue
> lock so I have a race somewhere where it's not. Time for more looking.
This is about the only place I can see the run_list is looked at unlocked. Can
you see if this simple patch helps? The debug patch is unnecessary now.
Thanks!
--
Ensure checking task_queued() is only done under runqueue lock.
Signed-off-by: Con Kolivas <[EMAIL PROTECTED]>
---
kernel/sched.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
Index: linux-2.6.21-rc4-mm1/kernel/sched.c
===================================================================
--- linux-2.6.21-rc4-mm1.orig/kernel/sched.c 2007-03-26 08:54:15.000000000
+1000
+++ linux-2.6.21-rc4-mm1/kernel/sched.c 2007-03-26 08:55:21.000000000 +1000
@@ -3421,16 +3421,16 @@ static inline void rotate_runqueue_prior
static void task_running_tick(struct rq *rq, struct task_struct *p, int tick)
{
- if (unlikely(!task_queued(p))) {
- /* Task has expired but was not scheduled yet */
- set_tsk_need_resched(p);
- return;
- }
/* SCHED_FIFO tasks never run out of timeslice. */
if (unlikely(p->policy == SCHED_FIFO))
return;
spin_lock(&rq->lock);
+ if (unlikely(!task_queued(p))) {
+ /* Task has expired but was not scheduled off yet */
+ set_tsk_need_resched(p);
+ goto out_unlock;
+ }
/*
* Accounting is performed by both the task and the runqueue. This
* allows frequently sleeping tasks to get their proper quota of
--
-ck
-
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