Re: 2.6.9-rc2-mm4 ps hang ?

[Badari Pulavarty]

On Fri, 2004-10-01 at 17:44, Andrew Morton wrote:
> Badari Pulavarty <pbadari@xxxxxxxxxx> wrote:
> >
> > 
> >  On Fri, 2004-10-01 at 16:49, Andrew Morton wrote:
> >  > Badari Pulavarty <pbadari@xxxxxxxxxx> wrote:
> >  > >
> >  > > Here is the full sysrq-t output.
> >  > 
> >  > What's this guy up to?
> >  ...
> >  > 
> >  > Something is seriously screwed up if it's stuck in try_to_wake_up().  Tried
> >  > generating a few extra traces?
> >  > 
> >  > Then again, maybe we're missing an up_read() somewhere.  hrm, I'll check.
> >  > 
> > 
> >  It reproduced again. I think this is the one causing all the troubles..
> > 
> >  db2fmcd       D ffffffff80132e2a     0 10854   7636                    
> >  (NOTLB)
> >  00000101bae85ef8 0000000000000002 0000020800000018 00000101d9ddd550
> >         0000000100000084 000001016d490e20 000001016d491158
> >  00000101d9ddd550
> >         0000000000000206 ffffffff801353cb
> >  Call Trace:<ffffffff801353cb>{try_to_wake_up+971}
> >  <ffffffff804455f0>{__down_write+128}
> >         <ffffffff80125e6f>{sys32_mmap+143}
> >  <ffffffff80124af1>{ia32_sysret+0}
> > 
> >  when I tried looking at /proc/10854 - it hung.
> 
> OK, so maybe that CPU is spinning in try_to_wake_up().  Can you tell if one
> CPU is busy when this happens?

CPU is not busy when this happens. Process is "D".
I traced few times when this happens, its always stuck there only.


> 
> Or you could try Peter's suggestion:
> 
> --- 25/kernel/sched.c~a	2004-10-01 17:43:32.500700488 -0700
> +++ 25-akpm/kernel/sched.c	2004-10-01 17:43:34.754357880 -0700
> @@ -1606,7 +1606,7 @@ out_set_cpu:
>  		task_rq_unlock(rql, &flags);
>  		/* might preempt at this point */
>  		rql = task_rq_lock(p, &flags);
> -		adjust_sched_timestamp(p, old_rq);
> +//		adjust_sched_timestamp(p, old_rq);
>  		old_state = p->state;
>  		if (!(old_state & state))
>  			goto out;

I will try this patch. Only problem is it happens very random.

Thanks,
Badari

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