Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752478Ab2FEPPr (ORCPT ); Tue, 5 Jun 2012 11:15:47 -0400 Received: from mail.skyhub.de ([78.46.96.112]:35117 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751913Ab2FEPPp (ORCPT ); Tue, 5 Jun 2012 11:15:45 -0400 Date: Tue, 5 Jun 2012 17:15:42 +0200 From: Borislav Petkov To: ShuoX Liu Cc: "linux-kernel@vger.kernel.org" , Yanmin Zhang , "Luck, Tony" , Andrew Morton , "andi@firstfloor.org" , Ingo Molnar Subject: Re: [PATCH v5 2/2] x86 mce: use new printk recursion disabling interface Message-ID: <20120605151542.GA10669@x1.osrc.amd.com> Mail-Followup-To: Borislav Petkov , ShuoX Liu , "linux-kernel@vger.kernel.org" , Yanmin Zhang , "Luck, Tony" , Andrew Morton , "andi@firstfloor.org" , Ingo Molnar References: <4FBF3295.7090608@intel.com> <3908561D78D1C84285E8C5FCA982C28F192F4D39@ORSMSX104.amr.corp.intel.com> <1338165058.14538.209.camel@ymzhang.sh.intel.com> <4FC2E8CF.2040109@intel.com> <4FC2E944.6060903@intel.com> <20120604171202.GA8533@x1.osrc.amd.com> <1338856360.14538.220.camel@ymzhang.sh.intel.com> <20120605081448.GA7097@liondog.tnic> <4FCDD72A.9030701@intel.com> <4FCDD78A.3070106@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <4FCDD78A.3070106@intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2067 Lines: 55 On Tue, Jun 05, 2012 at 05:55:22PM +0800, ShuoX Liu wrote: > From: ShuoX Liu > > On x86 machines, some times MCE happens just when kernel calls printk > to output some log info to serial console, while usually MCE module in > kernel is used to print out some hardware error information, such like > bad cache or bad memory bank. That causes printk recursion and printk > would omit MCE printk output. > > We hit it when running MTBF testing on Android ATOM mobiles. > > Here in mce_panic, we choose to disable printk recursion to make sure > MCE logs printed out. > > Signed-off-by: Yanmin Zhang > Signed-off-by: ShuoX Liu > --- > arch/x86/kernel/cpu/mcheck/mce.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c > index 2afcbd2..906e838 100644 > --- a/arch/x86/kernel/cpu/mcheck/mce.c > +++ b/arch/x86/kernel/cpu/mcheck/mce.c > @@ -306,6 +306,7 @@ static void mce_panic(char *msg, struct mce *final, char *exp) > { > int i, apei_err = 0; > > + printk_recursion_check_disable(); > if (!fake_panic) { > /* > * Make sure only one CPU runs in machine check panic > @@ -360,6 +361,7 @@ static void mce_panic(char *msg, struct mce *final, char *exp) > panic(msg); > } else > pr_emerg(HW_ERR "Fake kernel panic: %s\n", msg); > + printk_recursion_check_enable(); Ok, let me ask this again: why not disable the printk recursion check in the function that actually _prints_ the MCE, i.e. print_mce() instead of here in mce_panic() which does a whole bunch of other stuff and it can also return without printing any MCE to dmesg? Are you interested in seeing the printk's from mce_panic? Why? Thanks. -- Regards/Gruss, Boris. -- 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/