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From: "Johan Kullstam" <kullstam@ne.mediaone.net>
To: linux-kernel@vger.kernel.org
Subject: Re: 2.4.7p6 hang
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Date: 11 Jul 2001 20:17:48 -0400
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Andrea Arcangeli <andrea@suse.de> writes:

> On Wed, Jul 11, 2001 at 04:22:04PM +0200, Trond Myklebust wrote:
> > >>>>> " " == Andrew Morton <andrewm@uow.edu.au> writes:
> > 
> >      > Trond Myklebust wrote:
> >     >>
> >     >> ...  I have the same problem on my setup. To me, it looks like
> >     >> the loop in spawn_ksoftirqd() is suffering from some sort of
> >     >> atomicity problem.
> > 
> >      > Does a `set_current_state(TASK_RUNNING);' in spawn_ksoftirqd()
> >      > fix it?  If so we have a rogue initcall...
> > 
> > Nope. The same thing happens as before.
> > 
> > A couple of debugging statements show that ksoftirqd_CPU0 gets created
> > fine, and that ksoftirqd_task(0) is indeed getting set correctly
> > before we loop in spawn_ksoftirqd().
> > After this the second call to kernel_thread() succeeds, but
> > ksoftirqd() itself never gets called before the hang occurs.
> 
> ksoftirqd is quite scheduler intensive, and while its startup is
> correct (no need of any change there), it tends to trigger scheduler
> bugs (one of those bugs was just fixed in pre5). The reason I never seen
> the deadlock I also fixed this other scheduler bug in my tree:
> 
> 	ftp://ftp.us.kernel.org/pub/linux/kernel/people/andrea/kernels/v2.4/2.4.7pre5aa1/00_sched-yield-1
> 
> this one I forgot to sumbit but here it is now for easy merging:
> 
> --- 2.4.4aa3/kernel/sched.c.~1~	Sun Apr 29 17:37:05 2001
> +++ 2.4.4aa3/kernel/sched.c	Tue May  1 16:39:42 2001
> @@ -674,8 +674,10 @@
>  #endif
>  	spin_unlock_irq(&runqueue_lock);
>  
> -	if (prev == next)
> +	if (prev == next) {
> +		current->policy &= ~SCHED_YIELD;
>  		goto same_process;
> +	}
>  
>  #ifdef CONFIG_SMP
>   	/*

thank you.

this patch fixes things for me too.

i was freezing at boot, right after the kernel prints the line
Initializing RT netlink.
with both 2.4.7-pre5 and 2.4.7-pre6.

after applying this to 2.4.7-pre6, things are working fine (afaict
after just a few minutes...).

-- 
J o h a n  K u l l s t a m
[kullstam@ne.mediaone.net]
Don't Fear the Penguin!
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