linux-kernel - Re: [PATCH] x86-32: always use irq stacks

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Message-ID: <20100526130013.GA641@lst.de>
Date:	Wed, 26 May 2010 15:00:13 +0200
From:	Christoph Hellwig <hch@....de>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Christoph Hellwig <hch@....de>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86-32: always use irq stacks

On Wed, May 26, 2010 at 02:47:07PM +0200, Thomas Gleixner wrote:
> On Wed, 26 May 2010, Christoph Hellwig wrote:
> 
> > 
> > IRQ stacks provide much better safety against unexpected stack use from
> > interrupts, at the minimal downside of slightly higher memory usage.
> > Enable irq stacks also for the default 8k stack to minimize the problem
> > of stack overflows through interrupt activity.
> > 
> > This is what x86-64 and various other architectures already do.
> 
> We got rid of nested interrupts, so is this really a concern anymore ?

Yes, especially for deep storage stacks anything that can come in
unexpectedly from IRQ context is quite harmful.  It's a really cheap
way to avoid that indeterminism.

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