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From: Andreas Dilger <adilger@clusterfs.com>
To: Dave Hansen <haveblue@us.ibm.com>
Cc: linux-kernel@vger.kernel.org,
	"Martin J. Bligh" <Martin.Bligh@us.ibm.com>,
	linux-mm@kvack.org
Subject: Re: [RFC][PATCH]  4KB stack + irq stack for x86
Date: Wed, 2 Oct 2002 15:56:49 -0600	[thread overview]
Message-ID: <20021002215649.GY3000@clusterfs.com> (raw)
In-Reply-To: <3D9B62AC.30607@us.ibm.com>

On Oct 02, 2002  14:18 -0700, Dave Hansen wrote:
> I've resynced Ben's patch against 2.5.40.  However, I'm getting some 
> strange failures.  The patch is good enough to pass LTP, but 
> consistently freezes when I run tcpdump on it.
> 
> Although I don't have CONFIG_PREEMPT on, I have the feeling that I 
> need to disable preemption in common_interrupt() like it was before. 
>   Any insights would be appreciated.

I'm a little bit worried about this patch.  Have you tried something
like NFS-over-ext3-over-LVM-over-MD or so, which can have a deep stack?

We hit a bunch of deep stack problems like this (overflowing an 8kB stack)
even without interrupts involved when developing Lustre.  Granted, we
fixed some large stack allocations in the ext3 indexed-directory code
and in our own code, but I'm still worried that a 4kB stack is too small.

The Stanford checker folks would probably be able to run a test for
large stack allocations in 2.5.40 if you asked them nicely, and maybe
even do stack depths for call chains.

Alternately, you could set up an 8kB stack + IRQ stack and "red-zone"
the high page of the current 8kB stack and see if it is ever used.

Cheers, Andreas
--
Andreas Dilger
http://www-mddsp.enel.ucalgary.ca/People/adilger/
http://sourceforge.net/projects/ext2resize/

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  parent reply	other threads:[~2002-10-02 21:56 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-10-02 21:18 Dave Hansen
2002-10-02 21:43 ` Benjamin LaHaise
2002-10-02 22:13   ` Dave Hansen
2002-10-02 21:56 ` Andreas Dilger [this message]
2002-10-02 22:02   ` Martin J. Bligh
2002-10-03 11:10   ` Denis Vlasenko

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