Date: Fri, 20 Jun 2008 16:34:23 -0400 (EDT)
From: Mikulas Patocka <mpatocka@redhat.com>
To: David Miller <davem@davemloft.net>
cc: sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, agk@redhat.com
Subject: Re: stack overflow on Sparc64
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On Fri, 20 Jun 2008, David Miller wrote:

> From: Mikulas Patocka <mpatocka@redhat.com>
> Date: Fri, 20 Jun 2008 11:47:12 -0400 (EDT)
>
>> I took another few traces (to track the whole stack content) and there is
>> another problem: nested interrupts. Does Sparc64 limit them somehow?
>
> Two levels should be the deepest you will ever see, and this is
> equivalent to what you get on other platforms.
>
> That path occurs when softirq processing re-enabled HW interrupts when
> returning from the top-level interrupt.

And what if network softirq happened here? How much stack does it consume?

The whole overflowed stack trace has 75 functions, I was able to get rid 
of 9 by avoiding bio_endio recursion and 10 by turning simple functions 
into inlines. --- so is it enough or not enough for possible networking 
calls?

Maybe a good thing would be to add a check for stack size to __do_softirq 
and handing the softirq to ksoftirqd if there's not enough space.

Mikulas
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