From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754752Ab0EZNAX (ORCPT ); Wed, 26 May 2010 09:00:23 -0400 Received: from verein.lst.de ([213.95.11.210]:57204 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753578Ab0EZNAU (ORCPT ); Wed, 26 May 2010 09:00:20 -0400 Date: Wed, 26 May 2010 15:00:13 +0200 From: Christoph Hellwig To: Thomas Gleixner Cc: Christoph Hellwig , x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86-32: always use irq stacks Message-ID: <20100526130013.GA641@lst.de> References: <20100526110923.GA28414@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.28i X-Spam-Score: 0 () Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.