From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761102AbXIXW0I (ORCPT ); Mon, 24 Sep 2007 18:26:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755398AbXIXWZz (ORCPT ); Mon, 24 Sep 2007 18:25:55 -0400 Received: from smtp2.linux-foundation.org ([207.189.120.14]:47355 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753568AbXIXWZy (ORCPT ); Mon, 24 Sep 2007 18:25:54 -0400 Date: Mon, 24 Sep 2007 15:25:32 -0700 From: Andrew Morton To: Dave Hansen Cc: linux-kernel@vger.kernel.org, hch@infradead.org Subject: Re: [PATCH 24/25] r/o bind mounts: track number of mount writers Message-Id: <20070924152532.305ec951.akpm@linux-foundation.org> In-Reply-To: <1190671602.26982.261.camel@localhost> References: <20070920195249.852667D5@kernel> <20070920195320.38C8E20D@kernel> <20070923231713.f81ee0db.akpm@linux-foundation.org> <1190671602.26982.261.camel@localhost> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.6; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 24 Sep 2007 15:06:42 -0700 Dave Hansen wrote: > On Sun, 2007-09-23 at 23:17 -0700, Andrew Morton wrote: > > It look like a false positive to me, but really, for a patchset of this > > complexity and maturity I cannot fathom how it could have escaped any > > lockdep testing. > > I test with lockdep all the time. The problem was that lockdep doesn't > complain until you have 8 nested locks, and I only tested on a 4-cpu > system. > > I lowered the lockdep nesting limit to 3, and got the warning on my > machine. > hm. I saw that warning on my 2-way. It has CONFIG_NR_CPUS=8 so perhaps the kernel has decided that this machine can possibly have eight CPUs. It's an old super-micro board, doesn't have ACPI. OEM ID: INTEL Product ID: 440BX APIC at: 0xFEE00000 Processor #0 6:8 APIC version 17 Processor #1 6:8 APIC version 17 I/O APIC #2 Version 17 at 0xFEC00000. Enabling APIC mode: Flat. Using 1 I/O APICs Processors: 2 ... Checking if this processor honours the WP bit even in supervisor mode... Ok. Calibrating delay using timer specific routine.. 1707.03 BogoMIPS (lpj=3414067) Mount-cache hash table entries: 512 CPU: After generic identify, caps: 0383fbff 00000000 00000000 00000000 00000000 00000000 00000000 00000000 CPU: L1 I cache: 16K, L1 D cache: 16K CPU: L2 cache: 256K CPU: After all inits, caps: 0383fbff 00000000 00000000 00000040 00000000 00000000 00000000 00000000 Intel machine check architecture supported. Intel machine check reporting enabled on CPU#0. Compat vDSO mapped to ffffe000. Checking 'hlt' instruction... OK. lockdep: not fixing up alternatives. CPU0: Intel Pentium III (Coppermine) stepping 03 lockdep: not fixing up alternatives. Booting processor 1/1 eip 2000 Initializing CPU#1 Calibrating delay using timer specific routine.. 1704.02 BogoMIPS (lpj=3408054) CPU: After generic identify, caps: 0383fbff 00000000 00000000 00000000 00000000 00000000 00000000 00000000 CPU: L1 I cache: 16K, L1 D cache: 16K CPU: L2 cache: 256K CPU: After all inits, caps: 0383fbff 00000000 00000000 00000040 00000000 00000000 00000000 00000000 Intel machine check architecture supported. Intel machine check reporting enabled on CPU#1. CPU1: Intel Pentium III (Coppermine) stepping 03 Total of 2 processors activated (3411.06 BogoMIPS). ExtINT not setup in hardware but reported by MP table ENABLING IO-APIC IRQs ..TIMER: vector=0x31 apic1=0 pin1=2 apic2=0 pin2=0 APIC timer registered as dummy, due to nmi_watchdog=1! checking TSC synchronization [CPU#0 -> CPU#1]: passed. Brought up 2 CPUs One would think that the kernel would work out that eight CPUs ain't possible on such a machine. But we don't seem to print out any info which allows me to confirm that this is really what the kernel did.