From: Ingo Molnar Subject: Re: 2.6.25-git2: BUG: unable to handle kernel paging request at ffffffffffffffff Date: Wed, 23 Apr 2008 19:40:06 +0200 Message-ID: <20080423174006.GA2739@elte.hu> References: <480D1CF1.7010300@gmail.com> <480D208A.9050909@gmail.com> <200804220254.45251.rjw@sisk.pl> <480DB493.6080004@gmail.com> <20080422095315.GA28014@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Zdenek Kabelac , Jiri Slaby , "Rafael J. Wysocki" , paulmck@linux.vnet.ibm.com, David Miller , Linux Kernel Mailing List , Andrew Morton , linux-ext4@vger.kernel.org, herbert@gondor.apana.org.au, Pekka Enberg , Christoph Lameter To: Linus Torvalds Return-path: Received: from mx2.mail.elte.hu ([157.181.151.9]:41335 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752696AbYDWRlW (ORCPT ); Wed, 23 Apr 2008 13:41:22 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: * Linus Torvalds wrote: > > CPU: L2 cache: 4096K > > CPU: Physical Processor ID: 0 > > CPU: Processor Core ID: 1 > > x86: PAT support disabled. > > SPIN IRQ ALREADY DISABLED > > Pid: 0, comm: swapper Not tainted 2.6.25 #57 > > > > Call Trace: > > [_spin_lock_irq+126/128] _spin_lock_irq+0x7e/0x80 > > [lock_ipi_call_lock+16/32] lock_ipi_call_lock+0x10/0x20 > > CPU1: Intel(R) Core(TM)2 Duo CPU T7500 @ 2.20GHz > > [start_secondary+68/206] start_secondary+0x44/0xce > > This is indeed an interesting issue: arch/x86/kernel/smpboot.c does an > IPI call to start_secondary, and yes, it looks suspicious to have that > lock_ipi_call_lock there (and in particular the unlock_ipi_call_lock > that enables interrupts within it). Ingo? hm, irqs already disabled isnt bad in itself and it happens all the time. The irq enabling in unlock_ipi_call_lock() should be OK. Any race with irqs there should at most result in a hung or crashed bootup, not in any memory corruption i believe. Ingo