From owner-freebsd-stable@FreeBSD.ORG Sat Oct 4 15:45:10 2014 Return-Path: Delivered-To: freebsd-stable@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id B471C2DE; Sat, 4 Oct 2014 15:45:10 +0000 (UTC) Received: from smtp1.multiplay.co.uk (smtp1.multiplay.co.uk [85.236.96.35]) by mx1.freebsd.org (Postfix) with ESMTP id 752C01A4; Sat, 4 Oct 2014 15:45:10 +0000 (UTC) Received: by smtp1.multiplay.co.uk (Postfix, from userid 65534) id B213C20E7089B; Sat, 4 Oct 2014 15:45:07 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.multiplay.co.uk X-Spam-Level: * X-Spam-Status: No, score=1.6 required=8.0 tests=AWL,BAYES_00,DOS_OE_TO_MX, FSL_HELO_NON_FQDN_1,RDNS_DYNAMIC,STOX_REPLY_TYPE autolearn=no version=3.3.1 Received: from r2d2 (82-69-141-170.dsl.in-addr.zen.co.uk [82.69.141.170]) by smtp1.multiplay.co.uk (Postfix) with ESMTP id D9EFF20E70899; Sat, 4 Oct 2014 15:45:05 +0000 (UTC) Message-ID: <5AB03244BE0C425AA475302F13F3A743@multiplay.co.uk> From: "Steven Hartland" To: "Glen Barber" References: <20141004024011.GC1199@hub.FreeBSD.org> <64F0D761D09546C7B47DFAA1551500BE@multiplay.co.uk> <20141004031614.GD1199@hub.FreeBSD.org> <6618E7E0B17D41D09DB9B0160C2D4DF1@multiplay.co.uk> <9E274FD2D44943ED9F9C6057068C8CE0@multiplay.co.uk> <20141004151651.GG1199@hub.FreeBSD.org> Subject: Re: Heads-up: Possible regression between 10.0-RELEASE and 10.1-BETA1 with '/ on ZFS' setup Date: Sat, 4 Oct 2014 16:45:00 +0100 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 Cc: FreeBSD Release Engineering Team , freebsd-stable@FreeBSD.org X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 04 Oct 2014 15:45:10 -0000 ----- Original Message ----- From: "Glen Barber" > On Sat, Oct 04, 2014 at 04:03:39PM +0100, Steven Hartland wrote: > > >>On Sat, Oct 04, 2014 at 03:51:39AM +0100, Steven Hartland wrote: > > >>> > This has been a known issue on i386 since the switch to Clang see UPDATING: > > >>> 20121223: > > >>> After switching to Clang as the default compiler some users of ZFS > > >>> on i386 systems started to experience stack overflow kernel panics. > > >>> Please consider using 'options KSTACK_PAGES=4' in such configurations. > > >>> > In my experience your millage may vary but essentially without 4 stack pages > > >>> > all bets are off in terms of stability. > > > > Oh and just looking at the code kern.kstack_pages is read only so wont have > > any effect, hence you will definitely need to set the kernel option as per > > the UPDATING entry. > > > > Indeed, it is readonly. I'm building kernel on the test VM, but may > have to get the kernel built somewhere else from a non-ZFS VM, because > the i386 VM with ZFS is unusable. > > I'm not familiar with these parts of the kernel internals. What is the > harm in making KSTACK_PAGES=4 the default in i386 GENERIC ? > I expect on the smaller hardware we'd be eating into precious memory, but its a good question. You can always detach the second disk while you build and then re-attach it after you have the new kernel installed if that helps? Regards Steve