From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932202AbWFDIui (ORCPT ); Sun, 4 Jun 2006 04:50:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932210AbWFDIui (ORCPT ); Sun, 4 Jun 2006 04:50:38 -0400 Received: from mail.ocs.com.au ([202.147.117.210]:62404 "EHLO mail.ocs.com.au") by vger.kernel.org with ESMTP id S932202AbWFDIui (ORCPT ); Sun, 4 Jun 2006 04:50:38 -0400 X-Mailer: exmh version 2.7.0 06/18/2004 with nmh-1.1-RC1 From: Keith Owens To: Ingo Molnar cc: Andrew Morton , linux-kernel@vger.kernel.org, "Barry K. Nathan" , Arjan van de Ven Subject: Re: [patch, -rc5-mm3] lock validator: fix ns83820.c irq-flags bug In-reply-to: Your message of "Sun, 04 Jun 2006 10:30:17 +0200." <20060604083017.GA8241@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Sun, 04 Jun 2006 18:50:27 +1000 Message-ID: <16537.1149411027@ocs3.ocs.com.au> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar (on Sun, 4 Jun 2006 10:30:17 +0200) wrote: >2) allowing the nesting of hardware interrupts only 'spreads out' >the handling of the current ISR, causing extra cachemisses that would >otherwise not happen. Furthermore, on architectures where ISRs share >the kernel stacks, enabling interrupts in ISRs introduces a much >higher kernel-stack-nesting and thus kernel-stack-overflow risk. It is worse than you think. A third party network driver enabled interrupts in its irq handler. For reasons that are still not clear, that allowed recursive interrupts from the same device. Unexpected I know, because the card's ISR should still have been masked, but the stack trace said otherwise. When multiple packets arrived for the same driver it drove multiple levels of kernel functions to handle them and completely blew the kernel stack, even though it was using a separate IRQ stack.