From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261748AbULJQQS (ORCPT ); Fri, 10 Dec 2004 11:16:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261741AbULJQQS (ORCPT ); Fri, 10 Dec 2004 11:16:18 -0500 Received: from mailfe09.swipnet.se ([212.247.155.1]:15570 "EHLO mailfe09.swip.net") by vger.kernel.org with ESMTP id S261759AbULJQKp (ORCPT ); Fri, 10 Dec 2004 11:10:45 -0500 X-T2-Posting-ID: 2Ngqim/wGkXHuU4sHkFYGQ== Subject: [PATCH] Warn about dangers of LVM/RAID stacking with 4KSTACKS From: Alexander Nyberg To: torvalds@osdl.org Cc: linux-kernel@vger.kernel.org Content-Type: text/plain Date: Fri, 10 Dec 2004 17:10:35 +0100 Message-Id: <1102695035.690.11.camel@boxen> Mime-Version: 1.0 X-Mailer: Evolution 2.0.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello Linus On x86 using software RAID on disks and then putting them together in LVM as a logical volume uses alot of the stack. I've read reports of doing this on volumes which are shared via NFS causes stack overruns which it indeed does, I just reproduced it here. We should play it safe and warn anyone before using CONFIG_4KSTACKS if the user intends to do software LVM/RAID stacking until this issue is resolved. Signed-off-by: Alexander Nyberg ===== arch/i386/Kconfig.debug 1.4 vs edited ===== --- 1.4/arch/i386/Kconfig.debug 2004-10-20 10:37:19 +02:00 +++ edited/arch/i386/Kconfig.debug 2004-12-10 17:00:01 +01:00 @@ -46,6 +46,8 @@ config DEBUG_PAGEALLOC This results in a large slowdown, but helps to find certain types of memory corruptions. +comment "Please read help if you intend to stack software RAID and LVM" + config 4KSTACKS bool "Use 4Kb for kernel stacks instead of 8Kb" help @@ -54,6 +56,10 @@ config 4KSTACKS running more threads on a system and also reduces the pressure on the VM subsystem for higher order allocations. This option will also use IRQ stacks to compensate for the reduced stackspace. + + Don't enable this if you intend to stack RAID and LVM on top of + each other. The stack may run out using this combination and + then bad things will happen. config X86_FIND_SMP_CONFIG bool