From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: Re: [PATCH][RT] x86: Fix an RT MCE crash Date: Thu, 30 Jun 2016 11:51:01 -0400 Message-ID: <20160630115101.6337c395@gandalf.local.home> References: <1467293089-27656-1-git-send-email-minyard@acm.org> <20160630094301.22d32ec1@gandalf.local.home> <5775316F.2020102@acm.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-rt-users@vger.kernel.org, Corey Minyard , Borislav Petkov To: Corey Minyard Return-path: Received: from smtprelay0047.hostedemail.com ([216.40.44.47]:52140 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752224AbcF3PwF (ORCPT ); Thu, 30 Jun 2016 11:52:05 -0400 In-Reply-To: <5775316F.2020102@acm.org> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On Thu, 30 Jun 2016 09:49:19 -0500 Corey Minyard wrote: > On 06/30/2016 08:43 AM, Steven Rostedt wrote: > > On Thu, 30 Jun 2016 08:24:49 -0500 > > minyard@acm.org wrote: > > > >> From: Corey Minyard > >> > >> On some x86 systems an MCE interrupt would come in before the kernel > >> was ready for it. Looking at the latest RT code, it has similar > >> (but not quite the same) code, except it adds a bool that tells if > >> MCE handling is initialized. Add the same bool for older versions. > >> > >> Signed-off-by: Corey Minyard > >> --- > >> arch/x86/kernel/cpu/mcheck/mce.c | 5 ++++- > >> 1 file changed, 4 insertions(+), 1 deletion(-) > >> > >> We noticed this issue on a new Broadwell system when we booted RT > >> on it. This patch is for 3.10, I'm not sure if it applies to > >> other kernel versions. > > Do you mean other 'older' versions? and that this works with the > > versions after 3.10 without this patch? > > I haven't look at supported kernel versions besides 3.10 and 4.4. > The fix was from the 4.4 version of this code. This patch fixes > v3.10-rt; I can look at finding which other versions need this. I > was planning to do this, but I wanted to get the patch out for > comments first. I'm not an MCE expert (I just Cc'd one though ;-) OK, so you are saying that the fix was from 4.4-rt? I can go and look for it, and if so, I can add it to the "backport" patches I need to do. Which I need to go and do that soon (backport patches from previous versions). It may already be in that list. -- Steve > > -corey > > > -- Steve > > > >> diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c > >> index aaf4b9b..7125584 100644 > >> --- a/arch/x86/kernel/cpu/mcheck/mce.c > >> +++ b/arch/x86/kernel/cpu/mcheck/mce.c > >> @@ -1365,6 +1365,7 @@ static void __mce_notify_work(void) > >> } > >> > >> #ifdef CONFIG_PREEMPT_RT_FULL > >> +static bool notify_work_ready __read_mostly; > >> struct task_struct *mce_notify_helper; > >> > >> static int mce_notify_helper_thread(void *unused) > >> @@ -1386,12 +1387,14 @@ static int mce_notify_work_init(void) > >> if (!mce_notify_helper) > >> return -ENOMEM; > >> > >> + notify_work_ready = true; > >> return 0; > >> } > >> > >> static void mce_notify_work(void) > >> { > >> - wake_up_process(mce_notify_helper); > >> + if (notify_work_ready) > >> + wake_up_process(mce_notify_helper); > >> } > >> #else > >> static void mce_notify_work(void)