Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754994AbaDQKYt (ORCPT ); Thu, 17 Apr 2014 06:24:49 -0400 Received: from mail.skyhub.de ([78.46.96.112]:48850 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751227AbaDQKYr (ORCPT ); Thu, 17 Apr 2014 06:24:47 -0400 Date: Thu, 17 Apr 2014 12:24:42 +0200 From: Borislav Petkov To: Peter Zijlstra Cc: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, atodorov@redhat.com, tony.luck@intel.com, gong.chen@linux.intel.com, jwboyer@fedoraproject.org, qmewlo@gmail.com, tglx@linutronix.de, linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/urgent] x86/mce: Fix CMCI preemption bugs Message-ID: <20140417102442.GA8215@pd.tnic> References: <20140417100944.GG11096@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20140417100944.GG11096@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 17, 2014 at 12:09:44PM +0200, Peter Zijlstra wrote: > On Thu, Apr 17, 2014 at 02:57:54AM -0700, tip-bot for Ingo Molnar wrote: > > Commit-ID: ea431643d6c38728195e2c456801c3ef66bb9991 > > Gitweb: http://git.kernel.org/tip/ea431643d6c38728195e2c456801c3ef66bb9991 > > Author: Ingo Molnar > > AuthorDate: Thu, 17 Apr 2014 10:25:53 +0200 > > Committer: Ingo Molnar > > CommitDate: Thu, 17 Apr 2014 10:28:42 +0200 > > > > x86/mce: Fix CMCI preemption bugs > > > > The following commit: > > > > 27f6c573e0f7 ("x86, CMCI: Add proper detection of end of CMCI storms") > > > > Added two preemption bugs: > > > > - machine_check_poll() does a get_cpu_var() without a matching > > put_cpu_var(), which causes preemption imbalance and crashes upon > > bootup. > > > > - it does percpu ops without disabling preemption. Preemption is not > > disabled due to the mistaken use of a raw spinlock. > > it is arch_spinlock that doesn't disable preemption. raw_spinlock > disables preemption just fine. Hohum, __raw_spin_lock_irqsave does preempt_disable(). And machine_check_poll should be running in irq context so why would the original issue happen? > kernel: [ 7.341085] BUG: using __this_cpu_write() in preemptible [00000000] code: modprobe/546 Unfortunately, I have only one line in a mail CCed to me. Color me confused. -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. -- -- 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/