Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756073AbYH0Nkr (ORCPT ); Wed, 27 Aug 2008 09:40:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755295AbYH0Nkh (ORCPT ); Wed, 27 Aug 2008 09:40:37 -0400 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:55394 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755074AbYH0Nkg (ORCPT ); Wed, 27 Aug 2008 09:40:36 -0400 Date: Wed, 27 Aug 2008 14:21:42 +0100 From: Alan Cox To: "Parag Warudkar" Cc: "Adrian Bunk" , "Linus Torvalds" , "Rusty Russell" , "Alan D. Brunelle" , "Rafael J. Wysocki" , "Linux Kernel Mailing List" , "Kernel Testers List" , "Andrew Morton" , "Arjan van de Ven" , "Ingo Molnar" , linux-embedded@vger.kernel.org Subject: Re: [Bug #11342] Linux 2.6.27-rc3: kernel BUG at mm/vmalloc.c - bisected Message-ID: <20080827142142.303cdba8@lxorguk.ukuu.org.uk> In-Reply-To: References: <200808261111.19205.rusty@rustcorp.com.au> <20080826183051.GB10925@cs181140183.pp.htv.fi> <20080826205916.GB11734@cs181140183.pp.htv.fi> <20080826232411.GC11734@cs181140183.pp.htv.fi> <20080827092528.780916bd@lxorguk.ukuu.org.uk> X-Mailer: Claws Mail 3.5.0 (GTK+ 2.12.11; x86_64-redhat-linux-gnu) Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a Lloegr o'r rhif cofrestru 3798903 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 Content-Length: 1020 Lines: 24 > By your logic though, XFS on x86 should work fine with 4K stacks - > many will attest that it does not and blows up due to stack issues. > > I have first hand experiences of things blowing up with deep call > chains when using 4K stacks where 8K worked just fine on same > workload. > > So there is definitely some other problem with 4K stacks. Nothing of the sort. If it blows up with a 4K stack it will almost certainly blow up with an 8K stack *eventually* - when a heavy stack usage coincides with a heavy stack using IRQ handler. You won't catch it in simple testing, you won't catch it in trivial simulation and it'll be incredibly hard to reproduce. Not the kind of bug you want in a production system really. IRQ stacks make things much more predictable. Alan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/