From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757481Ab0GNTCZ (ORCPT ); Wed, 14 Jul 2010 15:02:25 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:46804 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755436Ab0GNTCX (ORCPT ); Wed, 14 Jul 2010 15:02:23 -0400 Date: Wed, 14 Jul 2010 12:02:38 -0700 (PDT) Message-Id: <20100714.120238.112604503.davem@davemloft.net> To: tglx@linutronix.de Cc: hch@lst.de, mingo@elte.hu, mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org, rostedt@goodmis.org Subject: Re: [tip:x86/irq] x86: Always use irq stacks From: David Miller In-Reply-To: References: <20100708205302.GA23961@lst.de> <20100714151215.GA31825@lst.de> X-Mailer: Mew version 6.3 on Emacs 23.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Gleixner Date: Wed, 14 Jul 2010 17:27:01 +0200 (CEST) > On Wed, 14 Jul 2010, Christoph Hellwig wrote: > >> Turns out this wasn't a regression introduced by a commit, but it >> happens when CONFIG_FUNCTION_GRAPH_TRACER is enabled. From a quick >> look I have no idea why these would interact badly, especially as >> CONFIG_FUNCTION_GRAPH_TRACER works fine with irq stacks if the >> CONFIG_4KSTACKS options is set. > > So you're saying, that the problem appears when > CONFIG_FUNCTION_GRAPH_TRACER is enabled w/o being used and that it > exists prior to your patches with irq stacks and 8k stack size, but > works with 4k stacks. That's definitely more than odd. Some hard-coded check somewhere assuming kernel stack pages won't straddle a page boundary? Just a guess...